Directory UMM :Data Elmu:jurnal:J-a:Journal of Asian Earth Science:Vol19.Issue1-2.Feb2001:
Journal of Asian Earth Sciences 19 (2001) 97±128
www.elsevier.nl/locate/jseaes
Time-dependent seismicity in China
Changyuan Qin*, E.E. Papadimitriou, B.C. Papazachos, G.F. Karakaisis
Laboratory of Geophysics, University of Thessaloniki, GR-54006, Thessaloniki, Greece
Abstract
Precise zonation of the territory of China has been performed based on the active known faults, type of faulting and seismicity level. One
hundred and forty seven seismogenic regions were de®ned, forming 10 larger seismic areas, and the seismotectonic characteristics in each
one of them were investigated in detail. After checking for data accuracy and completeness of the shallow earthquakes (h # 60 km), the
regional time and magnitude predictable model was applied and the model parameters were estimated. Based on the model applicability in
the studied area, probabilities for the occurrence of strong (M $ 6.0) earthquakes during the next 10 years were calculated for each
seismogenic region. Statistical tests have been used proving the superiority of the model in comparison with the time independent one,
as well as in comparison with the actual earthquake occurrence. q 2001 Elsevier Science Ltd. All rights reserved.
Keywords: Time-dependent seismicity; Seismotectonics; Probabilities; China
1. Introduction
Many earthquake recurrence models have been proposed
so far. However, only a few of them have been accepted that
satisfactorily describe the seismic activity. The most prominent of them are seismic gaps (Imamura, 1928; Fedotov,
1965; Mogi, 1985) and time and slip-predictable models
(Bufe et al., 1977; Shimazaki and Nakata, 1980).
Earlier this century, Omori (1907) and Imamura (1928)
had explicitly stated the existence of seismic gaps. Fedotov
(1965) introduced the seismic cycle concept, which means
that the probability for the occurrence of a mainshock in a
certain fault increases with the time elapsed since the occurrence of the previous mainshock in this fault. The earlier
long-term prediction was made by Kelleher et al. (1973) and
McCann et al. (1979) based on the seismic gap concept. The
1978 Oaxaca earthquake in Mexico (M 7.7, 16.5N
96.5W) was successfully forecasted by this pattern (Ohtake
et al., 1981; Mogi, 1985). The seismic gaps, as Mogi (1985)
de®ned later, can be divided into two categories. (a) If great
earthquakes are phenomena whereby crustal stress gradually increases over a wide range, strain is accumulated, a
rupture occurs when the stress has reached the limit, and
stress and strain are released all at once, then places where
no great earthquake has occurred for a long time can be
regarded as possible sites for the next great earthquake.
(b) If the activity of small earthquakes falls off in the
focal region prior to a large earthquake, the appearance of
* Corresponding author.
E-mail address: [email protected] (C. Qin).
such a temporary inactive period is a warning of the occurrence of a large earthquake.
The time- and slip-predictable model originally proposed
by Shimazaki and Nakata (1980) can be summarized as, (a)
if the ®nal stress varies in time while the initial stress
remains constant, the regularity makes it possible, in principle, to predict the occurrence time of the coming earthquake (so-called ªtime-predictable recurrenceº), (b) if the
®nal stress remains constant and the initial stress varies, the
coseismic slip produced by the coming earthquake can be
determined prior to the event (so-called ªslip-predictable
recurrenceº). Shimazaki and Nakata (1980) presented
three example sequences of large thrust±fault earthquakes
in Japan and found a regularity showing that the larger the
earthquake, the longer the following quiet period. Bufe et al.
(1977) presented a model of seismic slip and recurrence
intervals for a segment fault in northern California and
proposed that a given time interval is proportional to the
amount of displacement in the preceding earthquake.
Sykes and Quittmeyer (1981) found that data on the geometry, seismic moment and repeat time of large shocks of both
the strike±slip and convergent types agree better with the
time-predictable model of earthquake recurrence than with
the slip-predictable model.
The seismic gap concept can only give information on the
spatial domain. It is insensitive to the time domain. The
time-predictable model is related with the displacement
produced by the former event, in a certain fault, which
can be indicative for the expected time of the next one,
since tectonic loading can be assessed. However, as of the
late 1980's, the time-dependent character of the occurrence
1367-9120/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved.
PII: S 1367-912 0(00)00019-5
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C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Fig. 1. Large faults in the territory of China. The gray arrows represent the horizontal motion based on the geological survey, whereas the larger arrows
represent the impacts from the Indian, the Paci®c and the Philippine plate (after Ma, 1987).
of earthquakes has quantitatively been studied and successfully been used in long-term earthquake prediction (Papazachos, 1988a,b, 1989, 1992). The author explicitly
expressed that the time interval elapsed from the last mainshock as well as the size of the following mainshock
depends on the magnitude of previous mainshock, introducing the ªregional time and magnitude predictable modelº.
This model holds for a ªseismogenic regionº, that is, for a
relatively small part of the lithosphere which includes the
rupture zone (fault, deformation volume) of the largest
mainshock of this part of the lithosphere as well as secondary faults where smaller mainshocks are generated.
Papazachos and Papaioannou (1993) further improved
the model by suggesting the following two relations which
give the occurrence time, Tt, and the surface wave magnitude, of the following mainshock, Mf, as a function of: the
magnitude of the smallest mainshock considered, Mmin, the
magnitude of the preceding mainshock, Mp, and the annual
moment rate, mo, for each seismogenic region. These two
relations have the following form:
log T bMmin 1 cMp 1 d log m0 1 q
1
Mf BMmin 1 CMp 1 D log m0 1 m
where b, c, d, q, B, C, D, m are parameters to be calculated.
Nowadays this model has been used worldwide (Karakaisis,
1993, 1994a,b,c; Panagiotopoulos, 1993, 1994, 1995; Papadimitriou, 1993, 1994a,b; Papadimitriou and Papazachos,
1994; Papazachos et al., 1994a,b,c, 1997a,b; Tsapanos and
Papazachos, 1994; Papazachos and Papadimitriou, 1996).
Many seismologists also found that the seismic activity in
China follows more or less the same pattern. So far as we
know, the earlier time dependent seismic phenomena were
used to analyze the seismic activity in large seismic region
(Xiansuihe fault) in southwest China as early as 1983 (Han
and Huang, 1983; Wen et al., 1988; Wen, 1989, 1990, 1993,
1995). Li et al. (1994) concluded that occurrences in groups,
are the fundamental feature of the strong earthquakes in
China. Tsapanos and Papazachos (1994) and Papazachos
et al. (1997b) did a quantitative analysis of time dependent
seismicity in China. Qin et al. (1999b) have showed the
validation of the regional time- and magnitude-predictable
model throughout China. Qin (2000) carried out a lot of tests
to show priority of the time- and magnitude-predictable
model over the time independent model. The present
paper, with the help of a large amount of seismotectonic,
geological, and seismic information, concerns the application of this model based on the relations shown in Eq. (1) to
investigate the temporal dependence of the mainshock
occurrence in China by applying the regional time and
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
99
Fig. 2. The thrust faulting type area along the Himalayas (from Qin et al., 2000).
magnitude predictable model. Moreover, based on the
model applicability, probabilities for the occurrence of
strong (M $ 6.0) mainshocks in each seismogenic region
were estimated, contributing in that way to seismic hazard
assessment in the studied area.
2. Method
The precise zonation, the calculation of the seismic
moment rate, and the declustering of the data, are prerequisites for the model application. The separation of a seismic
area into seismogenic regions is based on certain seismotectonic and geomorphologic criteria. Such criteria are:
spatial clustering of seismicity, topography variations
(grabens, troughs, etc.), dimensions of rupture zones of
large earthquakes (surface fault traces, distribution of aftershock volumes of recent events, tsunamigenic sources, well
documented focal areas of historical earthquakes) and
evidence for interactions between seismic events (Papazachos et al., 1997a). The seismic moment rate, expressed by
the term logmo, which takes the tectonic loading into consideration, is responsible in reducing the in¯uence of the
tectonic distribution so that the model can be used in very
complicated tectonic environment (Fig. 1).
2.1. Zonation
Although it was pointed out that the zonation is not critical for the results of the model, accurate zonation will
improve them (Papazachos et al., 1997a; Papazachos and
Papadimitriou, 1997). The characteristic property of a seis-
mogenic region is the interaction among its faults during the
important seismic excitations (redistribution of stress, etc.).
Therefore, zonation in the present case is the procedure of
de®ning, as accurately as possible, the boundaries of the
seismogenic regions. The territory of China has been
divided into 10 seismic areas, on the basis of the gross
seismotectonic and geological properties and on and fault
plane solutions' distribution.
Area A constitutes the large Himalayan thrust fault and is
the frontier of the Eurasian plate which is pushed northward
by the Indian plate (Fig. 2). Due to the northeastward intrusion of the Indian plate, the Himalayan front in southwestern
China is characterized completely by compression and is
undergoing rapid uplift (Molnar and Lyon-Caen, 1989;
Gao, 1996). This suggests that the fault planes dip northwards. The overall pattern of fault plane solutions is compatible with the subduction of the Indian plate in front of the
Himalaya Frontal Thrust. The mean P axis of this area has a
NNE direction almost normal to the Himalayan arc (Molnar
and Lyon-Caen, 1989). The seismicity in this place mainly
re¯ects the compressive stress between the two plates.
Area B is dominated by normal faulting going parallel to
Area A. The area along the Indus±Tsangpo Suture is
controlled by east±west extensive force. The mean T-axis
has east±west direction. It is considered as a transition area
between the thrust motion of the Himalayas and the strike±
slip-motion of the central Qinghai±Tibet plateau. These
normal faults are located at higher altitude (.5000 m),
which gradually change to strike±slip faults with the
decrease of the level northwards (Molnar and Lyon-Caen,
1989) (Fig. 3).
100
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Fig. 3. The normal faulting type area (from Qin et al., 2000).
Fig. 4. The strike±slip faulting area along the Kunlun, Xianshuihe and Red river faults (from Qin et al., 2000).
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
101
Fig. 5. The thrust faulting type areas (Area F, H) around the Qilianshan and Tienshan faults (from Qin et al., 2000).
In the Qinghai±Tibet plateau, three areas (C, D, and E)
dominated by strike±slip motion (Fig. 4), constitute the
special `creep' motion channel (Qin et al., 2000). The leftlateral Xianshuihe, Shanjiang (Anninghe, Zemuhe, Xiaojiang) faults and the right-lateral Red River and Jinsajiang
faults in Area C contrast with the other two regions. The
crustal motion caused by the seismic activity also showed
their difference. Area C moves in a NW-SE direction and at
the same time rotates clockwise (Xu and Deng, 1996;
England and Molnar, 1997; Qin et al., 2000). Area C
behaves like a special ªriverº which ª¯owsº southeastward.
The left-lateral Xiansuihe, Anninghe, Zemuhe, Xiaojiang
faults, and the right-lateral Jinsajiang and Red River faults
constitute the diamond clockwise rotating block (Fig. 1).
The large component of the clockwise rotation makes it
different from its adjacent areas. Area D, which is located
in the heart of the Qinghai±Tibet plateau, mainly moves
northeastward and is characterized by (right or left) lateral
strike±slip faulting. The Altun fault marks its northern edge,
whereas the Karakorum fault is the western border. The Kunlun
fault passes through this region (Fig. 1). The northeast horizontal motion is the main reason for its separation from Area C.
Area E, as the continuation of the special ªriverº, runs eastward
along the southernmost part of the southeast China. For the
same reason mentioned for Area D, the eastward horizontal
motion pattern in this area contrasts that of Area C (Fig. 4).
The northern belt is supposed to be developed from the
eastern boundary of the Tamir basin to the Tianshan thrust
faulting area (Area H, Fig. 5) (Avouac et al., 1993). The
whole thrust belt is considered as a resisting zone, which
retards the Indian pushing force. These two areas are mainly
distinguished by their seismic activity. The large Qilianshan
thrust (Gaudemer et al., 1995) fault passes through Area
F, which is characterized by intense seismic activity.
The large Gulang (M 7.7, 23 May 1927) and
Changma (M 7.5, 25 December 1932) earthquakes
have occurred here. It is believed that it forms the
northeastern bank of the special ªriverº, whereas Area
H constitutes the thrust fault belt in the northern part of
Qinghai±Tibet Plateau.
Area G is developed around the Ordos block in North
China that is considered as one of the hardest blocks in
China. Yinchuan, Hetao, Shanxi graben, and other secondary seismotectonic elements compose this area. Area I is
located in the northwesternmost part of China and is a less
active seismic area compared with the Tianshan region.
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C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Fig. 6. The location of the 10 areas and 147 seismogenic regions. The thick lines express the border of the 10 areas, whereas the light lines express the regions.
Area J is in the easternmost part of China and goes along the
big north south Tanlu fault.
These 10 seismic areas are further divided into several
seismogenic regions. By seismogenic region, we mean a
fault area with dimensions comparable to the fault of the
maximum earthquake ever recorded there, which contains
secondary faults as well. This de®nition is based on the
principle of fault interaction in a speci®c fault system. The
detailed division of the 10 areas into seismogenic sources is
a tool for a more detailed investigation of the time dependent seismicity. By using the information of the seismic
activity, the maximum magnitude earthquake, dimensions
of focal areas, etc., 147 seismogenic regions were totally
de®ned (Fig. 6) in the above 10 areas.
2.2. Seismic moment rate
The seismic moment rate, mo, is one of the important
parameters for the application of this model, since it
expresses the tectonic loading exerted in the volume of
each seismogenic region (Papazachos et al., 1997a). For
the determination of the annual moment rate in the present
case, a procedure suggested by Molnar (1979) was applied.
According to this procedure, the following relation gives the
number of events with seismic moment equal to or large
than Mo:
N Mo G:Mo2E
2
where
G 10a1bk=r ;
E
b
r
3
and a, b are the constants of the Gutenberg and Richter
(1944) relation
log N a 2 bM
4
normalized for 1 year, and r, k the parameters of the
moment±magnitude relation
log Mo rM 1 k:
5
For the present case, it is taken that r 1.5 and k 16.1
(Kanamori, 1977; Ekstrom and Dziewonski, 1988). The
next relation gives the rate of seismic moment release, mo
(dyn.cm.year 21),
mo
G
:M 12E
1 2 E o; max
6
where Mo,max is the seismic moment released by the maximum earthquake in the region with magnitude Mmax.
2.3. Data used and declustering procedure
The data set used in the present study is taken from the
catalogue that was published and distributed by the State
Seismological Bureau (SSB) of P. R. China. This catalog
was further checked and corrected accordingly with: (a) the
catalogue of Pacheco and Sykes (1992) that gives information on all large earthquakes (M $ 7.0) which occurred
during the present century; (b) The catalogue of Abe
(1981) that covers the same time period but gives information on smaller events (M $ 6.5) as well since 1930; and (c)
The ISC bulletins for the period 1966±1992 for smaller
magnitude events. The data of the corrected catalogue
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C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 1
Seismicity parameters for the 10 areas of China territory
No.
Area
qa
s qb
Ma
s mb
pa
s pb
l 10 c
SP10 d
1
2
3
4
5
6
7
8
9
10
Front Himalaya area
Himalaya area
Xianshuihe River Red River area
Qinghai±Tibet area
Southeast China area
Qilianshan area
Ordos area
Tianshan area
Northwest China area
East China area
7.74
7.72
7.67
7.57
7.76
7.67
7.91
7.65
7.85
7.63
0.25
0.27
0.28
0.33
0.30
0.40
0.30
0.25
0.26
0.34
2 6.44
2 6.28
2 6.15
2 6.15
2 6.39
2 6.23
2 6.45
2 6.16
2 6.45
2 5.90
0.42
0.50
0.46
0.42
0.39
0.44
0.57
0.50
0.44
0.60
6.16
6.08
6.11
5.97
6.12
6.05
6.25
6.08
6.23
6.06
0.31
0.28
0.29
0.30
0.25
0.37
0.24
0.26
0.24
0.34
3.56
5.78
6.44
4.00
0.44
3.78
2.00
4.44
1.33
1.55
5.78
5.63
7.29
5.66
0.86
4.06
1.32
4.10
2.22
1.79
a
b
c
d
q, m and p are the values of the parameters in the Eqs. (8) and (9).
s is the corresponding standard deviation.
l 10 is the average number of mainshocks with Ms $ 6.0 per decade.
SP10 is the sum of the probabilities of all seismogenic regions in each area.
have been found to be complete for the following time
periods and magnitude cutoffs (Qin et al., 1999a):
Period
1950±1995
1900±1995
1800±1995
Magnitude Cutoff
M $ 5.0
M $ 6.0
M $ 8.0
For the application of Eq. (1), only the main shocks, that
is the largest earthquakes during the seismic cycle, and their
occurrence times are needed. It is then necessary to de®ne
them, as well as their ªpreshocksº and ªpostshocksº in the
broad sense, as suggested by Papazachos et al. (1997a).
These investigators, based on a large sample of observations, proposed the following two relations for the calculation of the total duration of preshock, tp, and postshock, ta,
activity:
tp 3 years
7
log ta 0:06 1 0:13Mp
where Mp is the magnitude of the preceding mainshock. The
constant duration of the preshock activity and the increase
of the duration of the aftershock activity with the size of the
mainshock, is in accordance with the results of previous
investigators (Mogi, 1985; Karakaisis et al., 1991). This
declustering procedure proves to be a main procedure for
the model.
2.4. Estimation of the model parameters
Recently, Papazachos et al. (1997a) have shown that the
parameters b, c, d, B, C, and D of the empirical formulae are
the same for every seismogenic region and seismotectonic
environment. They have estimated these parameters by
using a large sample of data for mainshocks of the continental fracture system, that is, from seismogenic regions of
Circum±Paci®c and of Alpine±Himalayan belts. These
parameters were calculated from 1811 observations (T,
Mmin, Mp, Mf) from 274 seismogenic regions in 16 areas
worldwide (Papazachos et al., 1997a). Since this model
has been used all over the world and proven to be stable
(Papazachos et al., 1997a; Papazachos and Papadimitriou,
1997), the model parameters are kept the same as those
found by Papazachos et al. (1997a), except for the constants
q and m in Eq. (1). These two parameters must be calculated
for every tectonic area. Finally, Eq. (1) takes the form:
log T 0:19Mmin 1 0:33Mp 2 0:39 log m0 1 q
8
Mf 0:73Mmin 2 0:28Mp 1 0:40 log m0 1 m
where q and m are parameters that differ among different
seismic areas. Based on Eq. (8), the q and m values were
estimated for the 10 areas and are given in Table 1. These
two constants are considered as calibrating factors for each
seismic area. The data sample used for the calculation
consists of 665 sets (T, Mmin, Mp, and Mf) and concerns
147 seismogenic regions.
Fig. 7 illustrates the frequency distribution of log(T/Tt)
for the interevent times, T, of all 665 observations, together
with the best-®t normal distribution which has a mean value
of m 0.06 and a standard deviation of s 0.30. This
standard deviation is usually attributed to the intrinsic
limitations of the model as well as to the quality and quantity of input data and varies in different regions (Scholz,
1990). Papazachos et al. (1997a) found a standard deviation
equal to 0.28 for the seismogenic sources of the continental
fracture system. It is interesting to note that Nishenko and
Buland (1987) found a value equal to 0.21 for the corresponding intrinsic standard deviation for mainshocks in
plate boundaries. To compare the observed and the theoretical distributions, the Kolmogorov±Smirnov test was
applied. A signi®cance level of 0.91 was found, while the
Dk-value, i.e., the largest absolute difference between the
obtained and the theoretical cumulative relative frequencies,
is 0.02. The critical value of Dk at this level is equal to 0.05.
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C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Fig. 7. The lognormal distribution of the ratio T/Tt where T is the interevent
time between two successive mainshocks, and Tt is the time calculated from
the ®rst Eq. (7).
This means that the hypothesis of normal distribution of the
quantity log(T/Tt) is valid.
Fig. 8 shows the frequency of the difference,
MF 2 Mf, between the observed, MF, and the calculated
magnitude, Mf, by Eq. (8) for all the regions. The best
®t normal distribution with a mean value of m 20.04
and a standard deviation equal to s 0.48 is also
shown. The corresponding value that Papazachos et al.
(1997a) found for the continental fracture system was
equal to 0.36.
2.5. Model probabilities
Although the time of the occurrence of the expected
mainshock in a seismogenic region can be estimated
directly by Eq. (8), it is better to give the probability of
occurrence of a certain magnitude earthquake. This is due
to the fact that there is considerable ¯uctuation of the
observed repeat times, T, in respect to the corresponding
repeat times, Tt, given by Eq. (8).
The probability density functions or distributions of the
data used must be known in order to proceed in probability
determination. Once the distribution function is de®ned,
earthquake repeat time estimates can be presented in
terms of a conditional probability, which describes the likelihood of failure within a given time interval, t 1 dt,
provided that the event has not occurred prior to time t.
The form of the current model leads to the assumption
that the lognormal distribution appears to be more suitable
for the data set, and this is evidenced by Fig. 7. Based on the
above and taking into account the occurrence time of the
previous mainshock, the model probabilities were calculated in each seismogenic region.
Fig. 8. The normal distribution of the difference M 2 Mf, where M is the
magnitude of main shocks and Mf is the magnitude calculated from the
second Eq. (7).
2.6. Statistical tests
It must be noted that earthquake prediction hypotheses
are dif®cult to test. The dif®culties concern the lack of a
standard procedure for constructing a null hypothesis
against which the predictions may be tested and that most
predictions cover a long period and the hypotheses evolve
before they can be tested (Kagan and Jackson, 1994). A
question then arises to what extent the model is superior
to a random occurrence model (time-independent). In
order to address this question, the term cMp of the ®rst
relation of Eq. (1) is ignored. By doing this, all the mainshocks are ®tted without any limitation (i.e., randomly).
This forms the Gutenberg±Richter relation for the mainshocks. Therefore, the empirical relation that describes the
time independent model is as follows:
log T 039M min 2 0:29 log mo 1 p
9
where p is different from one area to another (Table 1).
A direct way to check the superiority of the model against
the classical time-independent model is to apply both
models to a catalog and to compare the results (model probabilities) to real observations. This test can be made in an a
posteriori way to a reliable and complete sample of data.
Since the current data set is complete for M $ 6.0 during the
time interval from 1900 to 1995 in China, these two methods have been applied on this sample in the following way
(Papazachos et al., 1997a).
For each one of the seismogenic areas where at least one
earthquake of M $ 6.0 occurred since 1901, and for each
possible decade of the sample period, the model probability
for the occurrence of a mainshock with magnitude M $ 6.0
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Fig. 9. The success ratio vs the probability given by the time-dependent
model (black circles) and time-independent model (squares) for the Himalayan area (Area B). The dashed line expresses full success.
was calculated. Each period starts just after the occurrence
of the ®rst mainshock and ends 1 decade after the occurrence
of the last mainshock (e.g. 1901±1910, 1902±1911,¼1987±
1996, when the ®rst mainshock occurred in 1901 and the last
one in 1987 in this region). The model probabilities were
estimated based on the model Eq. (8) and lognormal distribution of T/Tt. A corresponding `yes' or `no' was assigned to each
decade if such a mainshock had occurred or not, respectively.
Then, the total range of the calculated model probabilities was
divided in equal intervals (0.0±0.09, 0.1±0.19¼) and all
decades were grouped in these intervals according to their
model probabilities. Finally, the success ratio of the number
of `yes' to the total number `yes 1 no' of decades was calculated for each group. The same procedure was repeated by
calculating probabilities on the basis of the time-independent
seismicity model (Gutenberg±Richter law for distribution of
magnitudes, Poisson law for distribution in time) that is
expressed in Eq. (9).
The results of this test are shown in Fig. 9, where the
success ratios are plotted vs probabilities, P10, for both the
time-dependent model (solid circles) and the time-independent model (squares with cross). The dashed line which
means full success is also shown. This ®gure evidences
the fact that the model probabilities are closer to the real
earthquake occurrence and cover a larger probability range.
In order to compare these results quantitatively, the linear
regression analysis was applied in both cases. A slope equal
to 1.04 (slope equal to 1 corresponds to the full success)
was obtained for the model probabilities. The linear hypothesis is accepted at the 0.99 signi®cance level
(t 9.79 . t7,0.005 3.50). For the time independent model
probability a slope equal to 1.05 was found and is rejected
even at 0.95 signi®cance level (t 2.24 , t2,0.05 2.92). It
105
Fig. 10. The number of the mainshocks predicted vs the mean number of
mainshocks in 1 decade for the 10 seismic areas marked by letters. The dash
line means that the actual number is equal to the predicted one.
is worth to note here the limited range of values obtained.
Therefore, this test shows the effectiveness of the regional
time predictable model and its superiority with respect to the
classical time-independent model for long interevent times
(Papazachos et al., 1997a, 1997b).
A second test has also been applied to examine whether the
calculated probabilities express the actual rate of earthquake
occurrence. As an estimation of the expected number of mainshocks with M $ 6.0 in each seismic area during the next
decade (1996±2005), the sum of the calculated probabilities,
SP10, can be considered for all seismogenic regions in each
seismic area. This sum can be compared with the average
number, l 10, of such observed earthquakes per decade, as
this number is deduced from the complete sample of data
available. This comparison can indicate the level of expected
seismic activity in the area, according to the model, with
respect to the mean seismic activity. The estimated values
are shown in Table 1 and plotted in Fig. 10, where the line is
the bisector. From this Fig. we can see that the number of
mainshocks predicted are close to the actual rates in almost
all the 10 areas. Exceptions are areas A and D where the sum of
the probabilities was found to be larger than the mean occurrence rate. This is probably due to an expected high active
period in these areas during the next decade.
3. Application of the model and results obtained
Based on Eq. (8) and the parameters q and m estimated
separately for each seismic area, the probabilities for the
occurrence of strong (M $ 6.0) earthquakes in the next 10
years, as well as the magnitude of the expected mainshock
can be calculated. The results obtained are shown in Table 2.
106
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2
Seismicity parameters (b, a, Mmax, mo) and expected strong mainshocks for each seismogenic region in the 10 areas of China territory. P10 is the model
probability for the occurrence of a mainshock with Ms $ 6.0 during the next 10 years and Mf is the most probable magnitude of the expected mainshock. The
last two columns give the year of occurrence and the cumulative magnitude a, M, of the mainshocks occurred in each seismogenic region
Region
Latitude
1
35.5
36.4
34.5
33.5
33.5
34.5
31.7
30.5
31.7
31.1
30.8
29.5
30.5
30.8
29.8
28.4
29.5
72.0
73.3
75.5
74.0
74.0
75.5
78.1
77.0
78.1
79.5
80.0
79.2
77.0
80.0
82.4
81.8
79.2
28.4
29.8
28.9
27.5
27.5
28.9
28.4
27.0
28.4
28.4
26.6
27.0
8
9
2
3
4
5
6
7
10
11
12
Longitude
b
Mmax
logmo
Mf
Year
M
3.58
0.93
6.0
23.52
9
5.7
1981-09-12
6.0
4.22
0.93
8.3
25.47
76
6.5
7.0
24.35
1
5.7
1905-04-05
1967-02-20
1980-08-23
1986-04-26
1962-07-14
1969-06-22
1986-07-16
1991-10-20
8.3
6.0
5.5
5.3
5.0
5.1
5.1
7.0
3.84
0.93
4.39
0.93
7.1
24.96
50
6.1
4.06
0.93
7.0
24.57
44
6.0
1916-08-28
1945-06-04
1953-02-23
1958-12-28
1980-07-29
1936-05-27
1954-09-04
1973-10-16
7.1
6.5
5.6
6.7
6.5
7.0
6.4
5.1
81.8
82.4
84.8
84.2
84.2
84.8
86.8
86.4
86.8
89.7
89.6
86.4
4.09
0.93
8.0
25.17
68
6.3
1833-08-26
1956-07-03
1974-03-24
8.0
5.7
6.2
4.08
0.93
8.3
25.33
76
6.4
89.6
89.7
93.0
93.2
4.33
0.93
7.5
25.13
64
6.3
28.7
29.8
28.2
27.3
27.0
29.8
30.8
29.5
28.2
93.0
94.2
95.5
94.7
93.2
94.2
95.3
96.8
95.5
4.43
0.93
7.3
25.11
53
6.1
1934-01-15
1960-08-12
1965-01-12
1971-12-04
1980-11-20
1990-01-09
1931-09-13
1941-01-21
1950-08-17
1954-02-23
1964-04-13
1985-10-13
1995-02-17
1947-07-29
1964-10-22
1985-08-01
8.3
5.0
5.7
5.7
6.1
5.1
6.5
6.8
5.8
6.0
6.2
5.0
5.7
7.3
6.7
5.7
26.6
28.4
28.7
27.0
4.37
0.93
7.0
24.88
47
6.0
29.5
27.8
27.6
28.2
26.1
27.6
27.8
27.2
26.1
96.8
97.4
95.7
95.5
95.9
95.7
97.4
97.5
97.5
4.57
0.93
8.6
25.99
32
5.9
1938-11-21
1950-10-08
1965-06-15
1981-10-24
1988-01-25
1992-02-06
1950-08-15
1987-01-09
6.0
6.6
5.0
5.7
5.6
5.7
8.6
5.0
4.41
0.93
7.6
25.26
68
6.3
1908-12-12
1950-08-22
1959-02-15
1962-09-22
1976-08-13
1984-11-28
7.6
6.3
5.7
6.4
6.3
5.7
a
P10(%)
107
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
Latitude
13
26.1
26.1
24.4
24.4
95.9
97.5
97.5
95.9
14
35.3
37.0
38.0
38.0
36.4
35.3
36.4
33.5
32.4
33.5
32.7
31.1
31.7
32.4
32.7
31.7
29.8
30.8
31.1
29.8
31.7
30.4
28.9
30.4
30.5
28.4
28.4
28.9
74.6
72.7
73.2
74.3
76.0
74.6
76.0
79.0
77.5
79.0
80.5
79.5
78.1
77.5
80.5
83.1
82.4
80.0
79.5
82.4
83.1
85.9
84.8
85.9
88.2
88.5
86.8
84.8
20
28.4
30.5
30.9
30.1
28.6
28.4
21
15
16
17
18
19
22
23
24
25
Longitude
b
Mmax
logmo
P10(%)
Mf
Year
M
4.40
0.93
7.5
25.20
56
6.6
3.93
0.93
6.7
24.27
13
6.0
1931-01-28
1962-02-21
1971-05-31
1981-08-17
1994-01-11
1950-08-20
1964-02-02
1982-07-02
1990-03-25
7.5
6.6
6.2
5.4
6.1
5.0
6.1
5.6
6.3
4.04
0.93
6.8
24.44
24
6.0
4.05
0.93
6.7
24.39
22
6.0
1951-08-26
1955-06-27
1963-04-12
1966-08-05
1975-01-11
1911-10-15
1966-03-06
1982-01-24
5.0
5.7
5.0
5.1
6.8
6.7
6.1
6.6
4.35
0.93
6.7
24.69
39
6.1
4.09
0.93
6.8
24.49
4
6.0
88.5
88.2
89.3
91.2
91.4
89.7
4.44
0.93
8.0
25.52
48
6.4
28.7
28.6
30.1
31.2
29.8
31.2
32.0
30.8
29.8
30.8
32.0
33.4
32.2
93.0
91.4
91.2
92.7
94.2
92.7
93.8
95.3
94.2
95.3
93.8
95.1
96.7
4.07
0.93
7.0
24.58
27
6.0
3.46
0.93
5.5
23.12
1913-03-06
1944-10-18
1957-04-14
1971-05-03
1918-02-05
1951-05-28
1958-11-24
1964-11-10
1970-02-27
1974-09-27
1988-09-03
1993-03-20
1901-04-21
1924-10-09
1935-05-21
1955-03-27
1980-02-22
1989-02-04
1992-07-30
1915-12-03
1951-12-03
1959-02-22
1968-01-13
1992-08-17
1959-11-18
1967-08-15
6.5
6.9
6.6
5.4
6.0
5.7
5.2
5.0
5.1
5.6
5.3
6.8
6.8
6.5
6.2
6.3
6.2
6.0
6.7
7.0
5.8
5.7
5.2
5.5
5.2
5.5
4.10
0.93
6.5
24.33
28
6.0
32.2
33.4
34.7
33.4
30.1
30.9
96.7
95.1
96.3
98.0
91.2
89.3
3.74
0.93
6.5
23.97
24
5.9
4.69
0.93
8.0
25.77
75
6.6
1950-08-26
1954-03-09
1961-12-04
1971-04-03
1985-01-16
1915-05-05
1977-12-16
1986-04-04
1989-04-13
1921-10-15
1925-01-12
5.2
5.8
5.9
6.6
5.1
6.5
5.3
5.1
5.4
6.2
6.5
a
±
±
108
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
26
27
28
29
30
31
32
33
34
35
36
Latitude
Longitude
a
b
Mmax
logmo
P10(%)
Mf
Year
M
1940-09-03
1951-11-18
1972-07-23
1977-05-28
1993-01-18
1955-08-04
1961-11-04
1971-05-23
6.3
8.1
6.0
6.3
6.3
5.0
5.5
6.1
1934-06-23
1959-04-27
1975-05-05
1983-06-15
1990-06-02
1994-06-03
1915-04-28
1950-09-19
1962-02-13
1992-02-03
1950-10-31
1966-03-14
1979-03-29
6.0
6.0
6.1
5.7
5.7
6.6
6.5
5.3
5.3
5.2
5.6
5.1
6.2
1923-10-20
1948-05-25
1960-05-03
1968-03-03
1979-11-06
1989-05-03
1951-03-17
1984-01-22
6.5
7.1
5.4
5.7
5.0
6.8
6.2
5.0
32.0
31.2
91.0
92.7
31.2
32.0
32.9
32.0
32.9
34.3
33.4
32.0
92.7
91.0
91.7
93.8
91.7
92.8
95.1
93.8
3.61
0.93
6.1
23.61
19
5.8
4.25
0.93
6.5
24.48
5
6.0
33.4
34.3
35.5
34.7
30.3
32.2
33.4
31.3
30.3
31.3
29.5
28.8
28.7
95.1
92.8
93.7
96.3
98.3
96.7
98.0
99.8
98.3
99.8
101.2
101.0
99.1
3.71
0.93
6.5
23.94
24
5.9
3.65
0.93
7.0
24.16
29
6.0
4.36
0.93
7.5
25.16
35
6.3
30.8
32.2
30.3
29.5
28.6
29.5
30.3
28.7
26.4
26.3
28.7
28.8
26.9
95.3
96.7
98.3
96.8
97.1
96.8
98.3
99.1
100.5
99.2
99.1
101.0
100.6
3.89
0.93
6.0
23.83
27
5.9
3.81
0.93
6.5
24.04
26
5.9
1921-051960-09-02
1986-02-06
6.5
5.7
5.1
4.22
0.93
7.5
25.02
59
6.4
28.7
26.3
26.1
27.2
27.8
28.6
24.1
26.3
26.4
24.4
99.1
99.2
97.5
97.5
97.4
97.1
99.7
99.2
100.5
101.1
3.86
0.93
6.5
24.09
35
6.0
1925-10-15
1933-06-07
1948-06-27
1961-06-27
1966-09-28
1976-09-03
1982-07-03
1993-07-17
1911-071950-08-22
6.0
6.2
6.4
6.1
6.1
5.4
5.4
5.9
6.5
6.1
4.11
0.93
7.0
24.62
53
6.4
21.5
24.1
24.4
21.7
100.5
99.7
101.1
102.3
4.54
0.93
6.7
24.88
26
6.4
1901-02-15
1925-03-16
1953-06-08
1963-04-23
1978-05-19
1986-03-13
1923-07-01
1942-02-01
1953-06-26
1965-07-03
1970-02-07
1973-08-16
6.5
7.0
5.0
6.0
5.6
5.5
6.5
6.7
5.7
6.1
6.2
6.7
109
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
Latitude
Longitude
a
b
Mmax
logmo
P10(%)
Mf
Year
M
1981-09-19
1993-01-27
1929-10-17
1941-10-31
1955-03-22
1966-09-19
1970-02-05
1976-05-29
1991-07-22
1923-06-22
1938-05-14
1941-05-16
1952-06-19
1984-04-24
1988-11-06
1913-081952-09-30
1962-02-27
1976-01-17
1988-01-10
1955-09-23
1964-11-20
1975-01-12
1993-08-14
6.0
6.5
6.9
6.2
6.2
5.6
5.7
7.2
5.3
7.1
6.0
7.4
6.5
6.0
7.6
6.0
6.7
5.6
6.7
5.7
6.9
5.2
5.6
6.1
37
23.5
24.4
26.1
26.3
24.1
97.8
97.5
97.5
99.2
99.7
4.68
0.93
7.0
25.19
41
6.3
38
21.5
23.5
24.1
21.5
98.6
97.8
99.7
100.5
4.81
0.93
7.3
25.49
28
6.3
39
29.5
28.8
27.4
26.9
26.9
24.4
26.4
26.9
26.9
24.7
24.7
26.9
27.4
26.6
25.0
23.2
24.4
25.0
23.2
101.2
103.0
102.6
101.9
100.6
101.1
100.5
100.6
101.9
102.3
102.3
101.9
102.6
104.1
104.0
101.6
101.1
104.0
104.0
4.28
0.93
7.5
25.08
52
6.4
4.25
0.93
6.9
24.70
34
6.4
4.17
0.93
8.0
25.25
68
6.6
1833-09-06
1927-03-15
1966-02-13
1985-04-18
8.0
6.2
6.3
6.3
4.50
0.93
7.3
25.18
40
6.3
38.3
36.9
38.0
38.2
39.0
35.2
36.9
37.6
36.0
35.2
36.0
34.3
33.5
32.4
32.7
33.5
34.3
33.6
31.7
32.4
33.6
33.1
32.5
30.4
31.7
77.8
75.4
74.3
74.5
76.6
77.3
75.4
76.6
78.5
77.3
78.5
80.2
79.0
81.4
80.5
79.0
80.2
82.1
83.1
81.4
82.1
83.4
84.7
85.9
83.1
3.04
0.93
7.0
23.55
1909-05-11
1913-12-21
1929-03-22
1940-04-06
1950-09-13
1965-05-24
1969-01-05
1980-06-18
1975-02-12
6.5
7.1
6.2
6.0
5.7
5.0
7.3
5.6
5.1
3.87
0.93
6.7
24.21
33
6.2
3.79
0.93
6.5
24.02
29
6.1
3.32
0.93
5.5
22.98
1925-12-07
1967-05-28
1980-02-14
1993-04-08
1914-10-09
1926-08-07
1953-01-08
1968-02-12
1950-08-17
1979-05-21
6.0
5.9
5.8
5.5
6.5
6.2
5.0
5.3
5.3
5.0
3.97
0.93
6.5
24.20
42
6.2
1955-01-29
1978-04-04
6.6
6.1
3.89
0.93
6.2
23.94
28
6.0
1947-02-10
1988-11-07
6.4
5.7
40
41
42
43
44
45
46
47
48
±
±
±
±
110
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
49
50
51
52
53
54
55
56
57
58
59
60
61
Latitude
Longitude
b
Mmax
logmo
P10(%)
Mf
Year
M
4.00
0.93
6.5
24.23
27
6.2
1935-01-03
1952-10-08
1961-12-08
1974-03-03
1986-06-21
1994-07-24
1908-08-20
1934-12-15
1963-01-22
1977-03-15
1980-06-04
1938-12-03
6.5
5.4
5.5
5.7
6.1
6.0
7.0
7.1
5.1
5.4
5.8
6.0
1902-08-31
1952-06-04
1956-03-05
1975-10-27
1993-06-14
1946-11-07
1973-11-22
1977-02-20
1986-07-07
6.8
5.2
5.7
5.2
5.1
6.2
5.1
5.7
6.1
1920-10-12
1948-02-13
1975-04-28
1987-04-10
1992-04-05
1952-04-02
1961-06-04
1977-01-14
1985-06-15
6.2
6.2
6.4
5.7
6.2
5.3
6.5
5.2
5.4
a
32.5
31.8
30.4
31.8
31.8
30.6
30.5
84.7
86.3
85.9
86.3
88.1
88.5
88.2
30.6
31.8
32.6
32.0
30.9
32.0
32.6
33.7
32.9
35.5
37.6
38.3
36.6
35.8
34.3
35.5
35.8
35.2
33.9
35.2
35.8
36.6
36.5
88.5
88.1
89.2
91.0
89.3
91.0
89.2
89.8
91.7
79.0
76.6
77.8
80.0
79.5
80.2
79.0
79.5
81.5
81.2
81.5
79.5
80.0
81.8
4.16
0.93
7.1
24.73
29
6.1
3.58
0.93
6.0
23.52
26
6.0
3.90
0.93
7.0
24.41
25
6.1
3.83
0.93
6.2
23.88
29
6.1
4.17
0.93
6.3
24.28
30
6.2
33.1
33.9
35.2
35.0
34.3
33.7
34.3
83.4
81.2
81.5
82.5
84.4
86.0
84.4
35.0
84.4
87.2
84.7
83.4
84.4
86.0
86.3
84.7
86.0
87.2
88.5
88.5
89.8
89.2
88.1
86.3
91.7
89.8
90.9
92.8
82.5
81.5
81.8
3.79
0.93
6.5
24.02
29
6.0
0.93
5.5
3.79
0.93
6.0
23.73
29
6.0
1960-01-31
1973-09-08
1985-10-04
5.0
6.1
5.3
4.00
0.93
6.5
24.23
31
6.1
1950-12-29
1965-06-18
1977-11-18
5.7
5.8
6.6
4.18
0.93
6.5
24.41
30
6.1
1952-09-14
1981-06-10
1986-08-21
5.8
6.2
6.7
3.67
0.93
5.8
23.50
±
1980-10-07
1989-10-08
5.8
5.4
35.8
34.7
32.5
33.1
34.3
33.7
31.8
32.5
33.7
34.7
34.2
34.2
33.7
32.6
31.8
31.8
32.9
33.7
35.0
34.3
35.0
35.2
36.5
82.5
±
111
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
Latitude
Longitude
36.8
35.8
33.7
34.7
35.8
35.0
34.7
35.8
36.6
35.8
35.8
36.8
37.5
36.6
36.6
37.5
38.2
37.4
35.8
36.6
37.4
36.7
35.0
35.8
36.7
36.2
34.3
35.0
36.2
35.5
35.5
36.2
37.2
36.6
36.2
36.7
37.7
37.2
36.7
37.4
38.2
37.7
37.4
38.2
39.0
38.2
34.7
35.5
36.6
35.9
33.4
34.7
35.9
35.5
34.8
32.0
33.4
34.8
33.1
30.3
32.0
33.1
31.1
82.6
84.4
89.8
87.2
88.5
90.9
87.2
84.4
86.0
88.5
84.4
82.6
84.0
86.0
86.0
84.0
85.5
87.9
88.5
86.0
87.9
89.8
90.9
88.5
89.8
91.6
92.8
90.9
91.6
93.7
93.7
91.6
92.5
94.6
91.6
89.8
91.0
92.5
89.8
87.9
89.8
91.0
87.9
85.5
87.5
89.8
96.3
93.7
94.6
97.5
98.0
96.3
97.5
99.0
99.5
99.2
98.0
99.5
100.7
100.6
99.2
100.7
101.9
b
Mmax
logmo
P10(%)
Mf
Year
M
4.11
0.93
6.2
24.16
25
6.2
1920-05-02
1946-02-20
1994-08-14
6.4
6.0
6.0
4.07
0.93
6.9
24.52
46
6.3
4.34
0.93
7.2
24.96
28
6.1
1951-10-11
1965-01-21
1973-07-14
1985-05-20
1924-07-12
1960-12-11
1991-06-17
5.0
5.5
6.9
6.3
7.4
5.5
5.3
2.95
0.93
5.0
22.32
±
1963-05-07
5.0
3.88
0.93
6.0
23.82
6.1
1959-11-11
1966-10-14
6.0
6.0
3.74
0.93
5.7
23.51
±
±
1980-03-07
1989-05-14
5.6
5.7
3.56
0.93
5.7
23.33
±
±
1952-10-01
1980-07-13
1986-12-21
5.0
5.7
5.3
3.42
0.93
5.5
23.08
±
±
1994-12-28
5.5
3.51
0.93
5.6
23.22
±
±
1994-11-28
5.6
4.09
0.93
6.8
24.49
16
6.1
4.72
0.93
6.9
25.17
48
6.4
1933-09-26
1957-08-23
1963-08-12
1993-10-02
1902-11-04
1963-04-19
6.7
5.0
5.1
6.8
6.9
6.9
4.63
0.93
7.5
25.43
66
6.6
1936-01-07
1971-03-24
7.5
6.4
4.09
0.93
7.4
24.83
29
6.1
1947-03-17
1961-05-18
7.4
5.2
4.56
0.93
7.5
25.36
45
6.3
1904-08-30
1919-05-29
1923-03-24
1967-08-30
7.5
6.4
7.1
6.1
a
±
34
112
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
Latitude
Longitude
77
31.1
29.4
28.8
29.5
30.3
27.4
29.4
29.4
28.6
26.6
101.9
103.2
103.0
101.2
100.6
102.6
103.2
104.6
104.8
104.1
24.4
25.0
26.6
28.6
22.5
23.2
25.0
24.4
22.5
24.4
23.6
21.7
23.6
24.0
23.3
22.2
21.6
21.7
24.0
26.8
25.6
23.3
22.2
23.3
25.6
24.2
24.2
25.6
27.8
26.6
38.2
39.0
39.7
38.8
37.2
37.7
38.2
38.8
38.4
36.6
37.2
38.4
37.7
36.6
37.7
37.0
35.9
37.0
78
79
80
81
82
83
84
85
86
87
88
89
90
b
Mmax
logmo
P10(%)
Mf
Year
M
4.35
0.93
7.7
25.25
85
6.8
1972-02-06
1932-03-07
1941-06-12
1955-04-14
1975-01-15
1989-06-09
1917-07-31
1936-04-27
1959-03-11
1966-10-11
1970-07-31
1974-05-11
1994-12-30
1955-05-27
1973-08-02
1985-12-02
7.3
6.0
6.0
7.4
6.2
5.6
7.3
6.9
5.3
5.1
5.4
6.8
6.1
5.0
5.2
5.4
4.55
0.93
7.3
25.23
58
6.6
107.5
104.0
104.1
104.8
107.0
104.0
104.0
107.5
107.0
107.5
111.0
110.5
111.0
113.8
114.6
115.6
113.0
110.5
113.8
116.5
118.0
114.6
115.6
114.6
118.0
119.5
119.5
118.0
121.6
122.8
89.8
87.5
89.5
91.7
92.5
91.0
89.8
91.7
93.3
94.6
92.5
93.3
95.6
94.6
95.6
98.5
97.5
3.43
0.93
6.0
23.37
±
±
3.62
0.93
5.7
23.39
±
±
1962-04-23
1982-10-27
5.5
5.7
3.86
0.93
6.7
24.20
22
6.0
1936-04-01
1958-09-25
1977-10-19
6.7
5.7
5.0
3.78
0.93
6.4
23.95
19
6.0
1911-05-15
1969-07-26
1986-01-28
6.0
6.4
5.2
3.70
0.93
6.1
23.70
21
6.0
1962-03-19
1982-02-25
1987-08-03
6.1
5.0
5.4
4.29
0.93
7.2
24.91
24
6.0
3.54
0.93
8.0
24.62
±
±
3.77
0.93
5.7
23.54
±
±
3.93
0.93
6.3
24.04
22
6.1
1906-03-28
1918-02-13
1968-04-01
1995-02-25
1960-07-21
1978-08-10
1985-11-28
1992-02-18
1960-11-17
1979-12-02
1991-01-06
1994-09-07
1976-01-02
1990-01-14
6.2
7.3
5.2
5.6
5.0
5.2
5.0
5.6
5.4
5.6
5.1
5.7
6.3
6.1
3.21
0.86
6.0
23.52
19
6.0
1952-10-06
1993-09-05
6.0
5.5
3.88
0.86
6.9
24.77
26
6.1
3.94
0.86
7.0
24.89
20
6.1
1957-05-04
1962-05-21
1972-08-30
1977-01-19
1985-08-12
1991-09-02
1952-03-21
5.5
6.9
5.7
5.9
5.4
5.5
5.0
98.5
a
113
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
91
92
93
94
95
96
97
98
99
100
101
102
103
Latitude
Longitude
36.4
35.5
35.5
35.9
33.4
35.5
35.5
34.0
33.4
34.0
32.8
31.1
32.8
35.5
36.4
34.6
33.7
29.4
29.4
31.1
31.0
31.1
32.8
33.7
33.2
31.0
101.0
100.5
99.0
97.5
100.5
99.0
100.5
101.8
100.5
101.8
102.8
101.9
102.8
100.5
101.0
104.0
103.5
104.6
103.2
101.9
104.5
101.9
102.8
103.5
105.5
104.5
33.7
34.6
35.7
35.5
33.2
34.6
36.4
37.2
35.7
a
b
Mmax
logmo
P10(%)
±
Year
M
1990-04-26
7.2
±
1950-06-18
1958-09-11
1978-02-21
5.0
5.1
5.1
Mf
3.07
0.86
5.1
22.80
3.48
0.86
6.0
23.79
22
6.0
1935-07-26
1952-11-01
1970-09-05
6.0
6.0
5.8
3.34
0.86
6.2
23.78
17
6.0
1974-09-23
1987-01-08
5.6
6.2
3.56
0.93
6.0
23.50
19
6.0
1962-07-01
1967-01-24
1970-02-24
5.1
5.5
6.0
4.67
0.93
8.0
25.75
56
6.6
103.5
104.0
104.7
106.6
105.5
104.0
101.0
102.2
104.7
3.34
0.86
8.0
24.93
32
6.4
1879-07-01
1933-08-25
1952-11-04
1960-11-09
1973-08-11
1976-08-16
1989-09-22
1936-08-01
1961-10-01
1987-10-25
8.0
7.3
5.7
6.8
6.1
7.1
6.8
6.0
5.8
5.5
3.41
0.86
7.0
24.36
20
6.0
36.4
37.0
38.2
37.2
37.2
38.2
39.1
38.2
101.0
98.5
99.5
102.2
102.2
99.5
100.3
103.0
2.96
0.86
5.4
22.89
1936-02-07
1957-07-18
1964-05-31
1968-12-22
1995-07-22
1952-01-27
1986-09-17
6.7
5.1
5.0
5.4
6.1
5.0
5.4
3.78
0.86
7.7
25.18
49
6.4
38.9
40.1
39.9
39.1
38.2
38.9
39.7
40.8
40.1
37.7
38.9
38.2
37.0
97.0
98.0
100.6
100.3
99.5
97.0
94.2
95.7
98.0
95.6
97.0
99.5
98.5
3.51
0.86
7.2
24.59
26
6.2
1927-05-23
1955-05-04
1958-11-30
1978-08-16
1986-08-26
1962-08-01
1969-10-17
1975-01-04
1993-10-26
7.7
5.0
5.1
5.0
6.4
5.4
5.1
5.3
6.4
3.69
0.86
7.5
24.96
35
6.4
1932-12-25
1951-12-27
1989-09-21
7.5
6.1
5.3
3.41
0.86
6.5
24.04
23
6.1
37.7
38.4
95.6
93.3
3.12
0.86
5.7
23.24
1927-03-16
1930-07-14
1938-08-23
1957-03-23
1980-04-18
1980-06-01
6.0
6.5
6.0
5.0
5.2
5.6
±
±
±
±
114
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
Latitude
Longitude
39.7
38.9
40.3
39.7
38.4
38.8
39.7
38.2
39.1
39.9
39.8
35.7
37.2
38.2
37.7
35.7
37.7
37.6
35.5
94.2
97.0
91.8
94.2
93.3
91.7
89.5
103.0
100.3
100.6
103.2
104.7
102.2
103.0
104.8
104.7
104.8
106.5
106.6
38.2
39.8
39.6
37.7
37.7
39.6
39.3
37.6
39.6
40.3
41.5
40.3
39.3
40.3
39.7
41.3
42.3
41.3
42.7
43.2
42.3
43.2
42.7
44.2
44.7
45.1
114
115
104
105
106
107
108
109
110
111
112
113
b
Mmax
logmo
P10(%)
Mf
Year
M
3.48
0.86
6.5
24.11
20
6.0
1922-10-17
1977-10-20
1987-02-26
6.5
5.1
6.4
3.46
0.86
7.0
24.41
14
5.7
1954-02-11
1989-09-04
7.0
5.1
3.16
0.86
6.2
23.60
1
5.6
1959-01-31
1990-10-20
5.2
6.2
3.90
0.86
8.4
25.75
17
5.9
103.0
103.2
104.8
104.8
104.8
104.8
106.7
106.5
104.8
105.0
106.5
107.6
106.7
91.8
89.5
88.1
90.3
88.1
86.9
89.2
90.3
89.2
86.9
85.6
86.1
88.2
3.54
0.86
7.0
24.49
15
5.8
1920-12-16
1959-01-31
1970-12-03
1982-04-14
1989-11-02
1954-07-31
8.4
5.2
5.5
5.7
5.4
7.0
3.56
0.86
8.0
25.15
47
6.3
1962-12-18
1971-06-28
1987-08-10
5.7
5.1
6.0
3.36
0.86
6.2
23.80
9
5.7
1959-10-06
1976-09-23
1991-01-13
5.0
6.2
5.8
3.39
0.86
6.4
23.96
11
6.0
1983-10-06
1987-12-22
5.5
6.4
3.35
0.86
5.6
23.40
±
1953-11-29
1983-12-15
1991-06-06
5.0
5.2
5.8
3.83
0.86
6.6
24.52
45
6.2
42.7
41.0
42.8
44.2
86.9
84.4
84.0
85.6
4.09
0.93
7.1
24.66
42
6.2
42.8
42.8
41.0
40.7
42.3
81.7
84.0
84.4
81.2
80.2
4.32
0.93
7.3
25.00
68
6.5
1907-05-13
1934-08-07
1953-04-26
1965-11-13
1980-11-06
1987-10-06
1906-12-23
1927-09-23
1960-11-30
1966-07-22
1972-04-09
1988-05-26
1993-02-03
1916- 1939-02-23
1949-02-24
1963-12-18
1970-11-29
1976-01-10
1979-03-29
1987-01-06
1995-05-12
6.0
6.0
6.2
6.6
5.9
5.0
7.1
6.7
5.0
5.0
5.7
5.2
5.7
6.0
6.0
7.3
5.8
5.0
5.8
6.0
6.2
5.1
a
±
115
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
Latitude
b
Mmax
logmo
P10(%)
Mf
Year
M
116
41.5
42.3
40.7
39.8
78.0
80.2
81.2
78.9
4.46
0.93
6.7
24.80
23
6.3
75.8
75.8
79.5
80.2
78.0
76.6
75.9
78.0
78.9
4.25
0.93
7.0
24.76
43
6.4
1915-12-17
1959-06-28
1969-02-12
1978-03-12
1987-01-24
1991-02-25
1938-06-21
1969-02-12
1978-03-25
1990-11-12
6.5
6.7
6.7
5.5
6.4
6.7
6.7
5.2
7.0
6.3
117
41.5
43.0
43.3
42.3
41.5
39.0
40.8
41.5
39.8
4.53
0.93
7.3
25.21
76
6.6
38.2
40.0
40.8
39.0
74.5
74.0
75.9
76.6
4.89
0.93
7.6
25.74
58
6.4
120
38.0
39.5
40.0
38.2
38.0
73.2
72.3
74.0
74.5
74.3
4.53
0.93
7.2
25.15
44
6.2
121
42.8
42.3
43.3
45.2
44.3
42.8
42.8
45.2
44.7
81.7
80.2
79.5
81.0
83.0
84.0
81.7
83.8
86.1
4.10
0.93
7.5
24.90
36
6.0
4.45
0.93
8.0
25.53
72
6.5
45.2
47.0
46.2
44.3
46.2
47.0
48.7
47.7
46.2
48.3
48.7
46.8
47.7
48.7
48.3
46.2
45.1
44.7
45.2
81.0
83.0
84.8
83.0
84.8
83.0
85.4
86.8
89.5
88.6
90.0
91.1
86.8
85.4
88.6
89.5
88.2
86.1
83.8
3.49
0.93
6.0
23.43
8
5.6
1902-08-31
1953-07-10
1961-04-14
1970-07-29
1977-12-19
1986-04-26
1995-05-15
1902-08-22
1919-07-24
1944-09-28
1955-04-15
1969-09-15
1978-01-08
1985-08-23
1918-12-01
1950-07-06
1963-10-16
1974-08-11
1987-08-06
1994-10-03
1921- 1951-10-31
1958-12-21
1967-01-14
1970-11-16
1812-03-08
1944-03-10
1955-04-24
1966-07-06
1973-06-03
1983-06-29
1990-10-25
1995-05-02
1932-09-11
1962-03-28
1975-04-23
7.3
6.2
7.0
6.1
6.2
5.6
5.7
7.6
6.5
6.8
7.2
5.9
6.1
7.4
6.5
5.3
6.7
7.3
5.4
5.5
6.5
5.4
6.7
5.0
5.5
8.0
7.1
6.6
5.0
6.0
5.3
5.8
6.1
6.0
5.0
5.0
119
3.61
0.86
6.8
24.43
2
5.8
1982-03-20
1990-06-14
5.0
6.8
3.99
0.86
7.7
25.39
60
6.4
1931-08-11
1970-09-19
1987-09-19
7.7
5.2
6.2
118
122
123
124
125
126
Longitude
a
116
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
Latitude
Longitude
46.2
44.3
46.2
46.8
44.8
44.3
43.2
45.1
46.2
42.8
44.3
44.8
43.3
42.3
43.2
44.3
42.8
40.3
41.5
41.5
39.7
39.7
41.5
41.0
39.3
39.3
41.0
40.8
39.0
37.5
39.3
39.0
37.2
34.5
37.8
37.5
37.2
34.0
34.0
37.2
36.7
33.8
37.2
39.0
38.7
36.7
39.0
40.8
40.5
38.7
37.8
39.7
39.3
37.5
36.7
38.7
40.5
40.5
39.0
43.8
40.0
39.0
40.5
84.8
91.3
89.5
91.1
93.0
91.3
89.2
88.2
89.5
92.7
91.3
93.0
94.3
90.3
89.2
91.3
92.7
107.6
106.5
109.5
109.5
109.5
109.5
113.0
112.7
112.7
113.0
115.0
114.4
112.0
112.7
114.4
113.6
110.0
110.0
112.0
113.6
112.5
112.5
113.6
115.9
115.2
113.6
114.4
116.0
115.9
114.4
115.0
116.5
116.0
110.0
109.5
112.7
112.0
115.9
116.0
116.5
120.0
120.0
125.4
126.0
120.0
120.0
b
Mmax
logmo
P10(%)
Mf
Year
M
0.86
6.5
24.23
25
6.0
1933-02-13
1954-02-19
1980-12-16
6.5
5.7
5.8
0.86
7.5
3.84
0.86
7.2
2
www.elsevier.nl/locate/jseaes
Time-dependent seismicity in China
Changyuan Qin*, E.E. Papadimitriou, B.C. Papazachos, G.F. Karakaisis
Laboratory of Geophysics, University of Thessaloniki, GR-54006, Thessaloniki, Greece
Abstract
Precise zonation of the territory of China has been performed based on the active known faults, type of faulting and seismicity level. One
hundred and forty seven seismogenic regions were de®ned, forming 10 larger seismic areas, and the seismotectonic characteristics in each
one of them were investigated in detail. After checking for data accuracy and completeness of the shallow earthquakes (h # 60 km), the
regional time and magnitude predictable model was applied and the model parameters were estimated. Based on the model applicability in
the studied area, probabilities for the occurrence of strong (M $ 6.0) earthquakes during the next 10 years were calculated for each
seismogenic region. Statistical tests have been used proving the superiority of the model in comparison with the time independent one,
as well as in comparison with the actual earthquake occurrence. q 2001 Elsevier Science Ltd. All rights reserved.
Keywords: Time-dependent seismicity; Seismotectonics; Probabilities; China
1. Introduction
Many earthquake recurrence models have been proposed
so far. However, only a few of them have been accepted that
satisfactorily describe the seismic activity. The most prominent of them are seismic gaps (Imamura, 1928; Fedotov,
1965; Mogi, 1985) and time and slip-predictable models
(Bufe et al., 1977; Shimazaki and Nakata, 1980).
Earlier this century, Omori (1907) and Imamura (1928)
had explicitly stated the existence of seismic gaps. Fedotov
(1965) introduced the seismic cycle concept, which means
that the probability for the occurrence of a mainshock in a
certain fault increases with the time elapsed since the occurrence of the previous mainshock in this fault. The earlier
long-term prediction was made by Kelleher et al. (1973) and
McCann et al. (1979) based on the seismic gap concept. The
1978 Oaxaca earthquake in Mexico (M 7.7, 16.5N
96.5W) was successfully forecasted by this pattern (Ohtake
et al., 1981; Mogi, 1985). The seismic gaps, as Mogi (1985)
de®ned later, can be divided into two categories. (a) If great
earthquakes are phenomena whereby crustal stress gradually increases over a wide range, strain is accumulated, a
rupture occurs when the stress has reached the limit, and
stress and strain are released all at once, then places where
no great earthquake has occurred for a long time can be
regarded as possible sites for the next great earthquake.
(b) If the activity of small earthquakes falls off in the
focal region prior to a large earthquake, the appearance of
* Corresponding author.
E-mail address: [email protected] (C. Qin).
such a temporary inactive period is a warning of the occurrence of a large earthquake.
The time- and slip-predictable model originally proposed
by Shimazaki and Nakata (1980) can be summarized as, (a)
if the ®nal stress varies in time while the initial stress
remains constant, the regularity makes it possible, in principle, to predict the occurrence time of the coming earthquake (so-called ªtime-predictable recurrenceº), (b) if the
®nal stress remains constant and the initial stress varies, the
coseismic slip produced by the coming earthquake can be
determined prior to the event (so-called ªslip-predictable
recurrenceº). Shimazaki and Nakata (1980) presented
three example sequences of large thrust±fault earthquakes
in Japan and found a regularity showing that the larger the
earthquake, the longer the following quiet period. Bufe et al.
(1977) presented a model of seismic slip and recurrence
intervals for a segment fault in northern California and
proposed that a given time interval is proportional to the
amount of displacement in the preceding earthquake.
Sykes and Quittmeyer (1981) found that data on the geometry, seismic moment and repeat time of large shocks of both
the strike±slip and convergent types agree better with the
time-predictable model of earthquake recurrence than with
the slip-predictable model.
The seismic gap concept can only give information on the
spatial domain. It is insensitive to the time domain. The
time-predictable model is related with the displacement
produced by the former event, in a certain fault, which
can be indicative for the expected time of the next one,
since tectonic loading can be assessed. However, as of the
late 1980's, the time-dependent character of the occurrence
1367-9120/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved.
PII: S 1367-912 0(00)00019-5
98
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Fig. 1. Large faults in the territory of China. The gray arrows represent the horizontal motion based on the geological survey, whereas the larger arrows
represent the impacts from the Indian, the Paci®c and the Philippine plate (after Ma, 1987).
of earthquakes has quantitatively been studied and successfully been used in long-term earthquake prediction (Papazachos, 1988a,b, 1989, 1992). The author explicitly
expressed that the time interval elapsed from the last mainshock as well as the size of the following mainshock
depends on the magnitude of previous mainshock, introducing the ªregional time and magnitude predictable modelº.
This model holds for a ªseismogenic regionº, that is, for a
relatively small part of the lithosphere which includes the
rupture zone (fault, deformation volume) of the largest
mainshock of this part of the lithosphere as well as secondary faults where smaller mainshocks are generated.
Papazachos and Papaioannou (1993) further improved
the model by suggesting the following two relations which
give the occurrence time, Tt, and the surface wave magnitude, of the following mainshock, Mf, as a function of: the
magnitude of the smallest mainshock considered, Mmin, the
magnitude of the preceding mainshock, Mp, and the annual
moment rate, mo, for each seismogenic region. These two
relations have the following form:
log T bMmin 1 cMp 1 d log m0 1 q
1
Mf BMmin 1 CMp 1 D log m0 1 m
where b, c, d, q, B, C, D, m are parameters to be calculated.
Nowadays this model has been used worldwide (Karakaisis,
1993, 1994a,b,c; Panagiotopoulos, 1993, 1994, 1995; Papadimitriou, 1993, 1994a,b; Papadimitriou and Papazachos,
1994; Papazachos et al., 1994a,b,c, 1997a,b; Tsapanos and
Papazachos, 1994; Papazachos and Papadimitriou, 1996).
Many seismologists also found that the seismic activity in
China follows more or less the same pattern. So far as we
know, the earlier time dependent seismic phenomena were
used to analyze the seismic activity in large seismic region
(Xiansuihe fault) in southwest China as early as 1983 (Han
and Huang, 1983; Wen et al., 1988; Wen, 1989, 1990, 1993,
1995). Li et al. (1994) concluded that occurrences in groups,
are the fundamental feature of the strong earthquakes in
China. Tsapanos and Papazachos (1994) and Papazachos
et al. (1997b) did a quantitative analysis of time dependent
seismicity in China. Qin et al. (1999b) have showed the
validation of the regional time- and magnitude-predictable
model throughout China. Qin (2000) carried out a lot of tests
to show priority of the time- and magnitude-predictable
model over the time independent model. The present
paper, with the help of a large amount of seismotectonic,
geological, and seismic information, concerns the application of this model based on the relations shown in Eq. (1) to
investigate the temporal dependence of the mainshock
occurrence in China by applying the regional time and
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
99
Fig. 2. The thrust faulting type area along the Himalayas (from Qin et al., 2000).
magnitude predictable model. Moreover, based on the
model applicability, probabilities for the occurrence of
strong (M $ 6.0) mainshocks in each seismogenic region
were estimated, contributing in that way to seismic hazard
assessment in the studied area.
2. Method
The precise zonation, the calculation of the seismic
moment rate, and the declustering of the data, are prerequisites for the model application. The separation of a seismic
area into seismogenic regions is based on certain seismotectonic and geomorphologic criteria. Such criteria are:
spatial clustering of seismicity, topography variations
(grabens, troughs, etc.), dimensions of rupture zones of
large earthquakes (surface fault traces, distribution of aftershock volumes of recent events, tsunamigenic sources, well
documented focal areas of historical earthquakes) and
evidence for interactions between seismic events (Papazachos et al., 1997a). The seismic moment rate, expressed by
the term logmo, which takes the tectonic loading into consideration, is responsible in reducing the in¯uence of the
tectonic distribution so that the model can be used in very
complicated tectonic environment (Fig. 1).
2.1. Zonation
Although it was pointed out that the zonation is not critical for the results of the model, accurate zonation will
improve them (Papazachos et al., 1997a; Papazachos and
Papadimitriou, 1997). The characteristic property of a seis-
mogenic region is the interaction among its faults during the
important seismic excitations (redistribution of stress, etc.).
Therefore, zonation in the present case is the procedure of
de®ning, as accurately as possible, the boundaries of the
seismogenic regions. The territory of China has been
divided into 10 seismic areas, on the basis of the gross
seismotectonic and geological properties and on and fault
plane solutions' distribution.
Area A constitutes the large Himalayan thrust fault and is
the frontier of the Eurasian plate which is pushed northward
by the Indian plate (Fig. 2). Due to the northeastward intrusion of the Indian plate, the Himalayan front in southwestern
China is characterized completely by compression and is
undergoing rapid uplift (Molnar and Lyon-Caen, 1989;
Gao, 1996). This suggests that the fault planes dip northwards. The overall pattern of fault plane solutions is compatible with the subduction of the Indian plate in front of the
Himalaya Frontal Thrust. The mean P axis of this area has a
NNE direction almost normal to the Himalayan arc (Molnar
and Lyon-Caen, 1989). The seismicity in this place mainly
re¯ects the compressive stress between the two plates.
Area B is dominated by normal faulting going parallel to
Area A. The area along the Indus±Tsangpo Suture is
controlled by east±west extensive force. The mean T-axis
has east±west direction. It is considered as a transition area
between the thrust motion of the Himalayas and the strike±
slip-motion of the central Qinghai±Tibet plateau. These
normal faults are located at higher altitude (.5000 m),
which gradually change to strike±slip faults with the
decrease of the level northwards (Molnar and Lyon-Caen,
1989) (Fig. 3).
100
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Fig. 3. The normal faulting type area (from Qin et al., 2000).
Fig. 4. The strike±slip faulting area along the Kunlun, Xianshuihe and Red river faults (from Qin et al., 2000).
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
101
Fig. 5. The thrust faulting type areas (Area F, H) around the Qilianshan and Tienshan faults (from Qin et al., 2000).
In the Qinghai±Tibet plateau, three areas (C, D, and E)
dominated by strike±slip motion (Fig. 4), constitute the
special `creep' motion channel (Qin et al., 2000). The leftlateral Xianshuihe, Shanjiang (Anninghe, Zemuhe, Xiaojiang) faults and the right-lateral Red River and Jinsajiang
faults in Area C contrast with the other two regions. The
crustal motion caused by the seismic activity also showed
their difference. Area C moves in a NW-SE direction and at
the same time rotates clockwise (Xu and Deng, 1996;
England and Molnar, 1997; Qin et al., 2000). Area C
behaves like a special ªriverº which ª¯owsº southeastward.
The left-lateral Xiansuihe, Anninghe, Zemuhe, Xiaojiang
faults, and the right-lateral Jinsajiang and Red River faults
constitute the diamond clockwise rotating block (Fig. 1).
The large component of the clockwise rotation makes it
different from its adjacent areas. Area D, which is located
in the heart of the Qinghai±Tibet plateau, mainly moves
northeastward and is characterized by (right or left) lateral
strike±slip faulting. The Altun fault marks its northern edge,
whereas the Karakorum fault is the western border. The Kunlun
fault passes through this region (Fig. 1). The northeast horizontal motion is the main reason for its separation from Area C.
Area E, as the continuation of the special ªriverº, runs eastward
along the southernmost part of the southeast China. For the
same reason mentioned for Area D, the eastward horizontal
motion pattern in this area contrasts that of Area C (Fig. 4).
The northern belt is supposed to be developed from the
eastern boundary of the Tamir basin to the Tianshan thrust
faulting area (Area H, Fig. 5) (Avouac et al., 1993). The
whole thrust belt is considered as a resisting zone, which
retards the Indian pushing force. These two areas are mainly
distinguished by their seismic activity. The large Qilianshan
thrust (Gaudemer et al., 1995) fault passes through Area
F, which is characterized by intense seismic activity.
The large Gulang (M 7.7, 23 May 1927) and
Changma (M 7.5, 25 December 1932) earthquakes
have occurred here. It is believed that it forms the
northeastern bank of the special ªriverº, whereas Area
H constitutes the thrust fault belt in the northern part of
Qinghai±Tibet Plateau.
Area G is developed around the Ordos block in North
China that is considered as one of the hardest blocks in
China. Yinchuan, Hetao, Shanxi graben, and other secondary seismotectonic elements compose this area. Area I is
located in the northwesternmost part of China and is a less
active seismic area compared with the Tianshan region.
102
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Fig. 6. The location of the 10 areas and 147 seismogenic regions. The thick lines express the border of the 10 areas, whereas the light lines express the regions.
Area J is in the easternmost part of China and goes along the
big north south Tanlu fault.
These 10 seismic areas are further divided into several
seismogenic regions. By seismogenic region, we mean a
fault area with dimensions comparable to the fault of the
maximum earthquake ever recorded there, which contains
secondary faults as well. This de®nition is based on the
principle of fault interaction in a speci®c fault system. The
detailed division of the 10 areas into seismogenic sources is
a tool for a more detailed investigation of the time dependent seismicity. By using the information of the seismic
activity, the maximum magnitude earthquake, dimensions
of focal areas, etc., 147 seismogenic regions were totally
de®ned (Fig. 6) in the above 10 areas.
2.2. Seismic moment rate
The seismic moment rate, mo, is one of the important
parameters for the application of this model, since it
expresses the tectonic loading exerted in the volume of
each seismogenic region (Papazachos et al., 1997a). For
the determination of the annual moment rate in the present
case, a procedure suggested by Molnar (1979) was applied.
According to this procedure, the following relation gives the
number of events with seismic moment equal to or large
than Mo:
N Mo G:Mo2E
2
where
G 10a1bk=r ;
E
b
r
3
and a, b are the constants of the Gutenberg and Richter
(1944) relation
log N a 2 bM
4
normalized for 1 year, and r, k the parameters of the
moment±magnitude relation
log Mo rM 1 k:
5
For the present case, it is taken that r 1.5 and k 16.1
(Kanamori, 1977; Ekstrom and Dziewonski, 1988). The
next relation gives the rate of seismic moment release, mo
(dyn.cm.year 21),
mo
G
:M 12E
1 2 E o; max
6
where Mo,max is the seismic moment released by the maximum earthquake in the region with magnitude Mmax.
2.3. Data used and declustering procedure
The data set used in the present study is taken from the
catalogue that was published and distributed by the State
Seismological Bureau (SSB) of P. R. China. This catalog
was further checked and corrected accordingly with: (a) the
catalogue of Pacheco and Sykes (1992) that gives information on all large earthquakes (M $ 7.0) which occurred
during the present century; (b) The catalogue of Abe
(1981) that covers the same time period but gives information on smaller events (M $ 6.5) as well since 1930; and (c)
The ISC bulletins for the period 1966±1992 for smaller
magnitude events. The data of the corrected catalogue
103
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 1
Seismicity parameters for the 10 areas of China territory
No.
Area
qa
s qb
Ma
s mb
pa
s pb
l 10 c
SP10 d
1
2
3
4
5
6
7
8
9
10
Front Himalaya area
Himalaya area
Xianshuihe River Red River area
Qinghai±Tibet area
Southeast China area
Qilianshan area
Ordos area
Tianshan area
Northwest China area
East China area
7.74
7.72
7.67
7.57
7.76
7.67
7.91
7.65
7.85
7.63
0.25
0.27
0.28
0.33
0.30
0.40
0.30
0.25
0.26
0.34
2 6.44
2 6.28
2 6.15
2 6.15
2 6.39
2 6.23
2 6.45
2 6.16
2 6.45
2 5.90
0.42
0.50
0.46
0.42
0.39
0.44
0.57
0.50
0.44
0.60
6.16
6.08
6.11
5.97
6.12
6.05
6.25
6.08
6.23
6.06
0.31
0.28
0.29
0.30
0.25
0.37
0.24
0.26
0.24
0.34
3.56
5.78
6.44
4.00
0.44
3.78
2.00
4.44
1.33
1.55
5.78
5.63
7.29
5.66
0.86
4.06
1.32
4.10
2.22
1.79
a
b
c
d
q, m and p are the values of the parameters in the Eqs. (8) and (9).
s is the corresponding standard deviation.
l 10 is the average number of mainshocks with Ms $ 6.0 per decade.
SP10 is the sum of the probabilities of all seismogenic regions in each area.
have been found to be complete for the following time
periods and magnitude cutoffs (Qin et al., 1999a):
Period
1950±1995
1900±1995
1800±1995
Magnitude Cutoff
M $ 5.0
M $ 6.0
M $ 8.0
For the application of Eq. (1), only the main shocks, that
is the largest earthquakes during the seismic cycle, and their
occurrence times are needed. It is then necessary to de®ne
them, as well as their ªpreshocksº and ªpostshocksº in the
broad sense, as suggested by Papazachos et al. (1997a).
These investigators, based on a large sample of observations, proposed the following two relations for the calculation of the total duration of preshock, tp, and postshock, ta,
activity:
tp 3 years
7
log ta 0:06 1 0:13Mp
where Mp is the magnitude of the preceding mainshock. The
constant duration of the preshock activity and the increase
of the duration of the aftershock activity with the size of the
mainshock, is in accordance with the results of previous
investigators (Mogi, 1985; Karakaisis et al., 1991). This
declustering procedure proves to be a main procedure for
the model.
2.4. Estimation of the model parameters
Recently, Papazachos et al. (1997a) have shown that the
parameters b, c, d, B, C, and D of the empirical formulae are
the same for every seismogenic region and seismotectonic
environment. They have estimated these parameters by
using a large sample of data for mainshocks of the continental fracture system, that is, from seismogenic regions of
Circum±Paci®c and of Alpine±Himalayan belts. These
parameters were calculated from 1811 observations (T,
Mmin, Mp, Mf) from 274 seismogenic regions in 16 areas
worldwide (Papazachos et al., 1997a). Since this model
has been used all over the world and proven to be stable
(Papazachos et al., 1997a; Papazachos and Papadimitriou,
1997), the model parameters are kept the same as those
found by Papazachos et al. (1997a), except for the constants
q and m in Eq. (1). These two parameters must be calculated
for every tectonic area. Finally, Eq. (1) takes the form:
log T 0:19Mmin 1 0:33Mp 2 0:39 log m0 1 q
8
Mf 0:73Mmin 2 0:28Mp 1 0:40 log m0 1 m
where q and m are parameters that differ among different
seismic areas. Based on Eq. (8), the q and m values were
estimated for the 10 areas and are given in Table 1. These
two constants are considered as calibrating factors for each
seismic area. The data sample used for the calculation
consists of 665 sets (T, Mmin, Mp, and Mf) and concerns
147 seismogenic regions.
Fig. 7 illustrates the frequency distribution of log(T/Tt)
for the interevent times, T, of all 665 observations, together
with the best-®t normal distribution which has a mean value
of m 0.06 and a standard deviation of s 0.30. This
standard deviation is usually attributed to the intrinsic
limitations of the model as well as to the quality and quantity of input data and varies in different regions (Scholz,
1990). Papazachos et al. (1997a) found a standard deviation
equal to 0.28 for the seismogenic sources of the continental
fracture system. It is interesting to note that Nishenko and
Buland (1987) found a value equal to 0.21 for the corresponding intrinsic standard deviation for mainshocks in
plate boundaries. To compare the observed and the theoretical distributions, the Kolmogorov±Smirnov test was
applied. A signi®cance level of 0.91 was found, while the
Dk-value, i.e., the largest absolute difference between the
obtained and the theoretical cumulative relative frequencies,
is 0.02. The critical value of Dk at this level is equal to 0.05.
104
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Fig. 7. The lognormal distribution of the ratio T/Tt where T is the interevent
time between two successive mainshocks, and Tt is the time calculated from
the ®rst Eq. (7).
This means that the hypothesis of normal distribution of the
quantity log(T/Tt) is valid.
Fig. 8 shows the frequency of the difference,
MF 2 Mf, between the observed, MF, and the calculated
magnitude, Mf, by Eq. (8) for all the regions. The best
®t normal distribution with a mean value of m 20.04
and a standard deviation equal to s 0.48 is also
shown. The corresponding value that Papazachos et al.
(1997a) found for the continental fracture system was
equal to 0.36.
2.5. Model probabilities
Although the time of the occurrence of the expected
mainshock in a seismogenic region can be estimated
directly by Eq. (8), it is better to give the probability of
occurrence of a certain magnitude earthquake. This is due
to the fact that there is considerable ¯uctuation of the
observed repeat times, T, in respect to the corresponding
repeat times, Tt, given by Eq. (8).
The probability density functions or distributions of the
data used must be known in order to proceed in probability
determination. Once the distribution function is de®ned,
earthquake repeat time estimates can be presented in
terms of a conditional probability, which describes the likelihood of failure within a given time interval, t 1 dt,
provided that the event has not occurred prior to time t.
The form of the current model leads to the assumption
that the lognormal distribution appears to be more suitable
for the data set, and this is evidenced by Fig. 7. Based on the
above and taking into account the occurrence time of the
previous mainshock, the model probabilities were calculated in each seismogenic region.
Fig. 8. The normal distribution of the difference M 2 Mf, where M is the
magnitude of main shocks and Mf is the magnitude calculated from the
second Eq. (7).
2.6. Statistical tests
It must be noted that earthquake prediction hypotheses
are dif®cult to test. The dif®culties concern the lack of a
standard procedure for constructing a null hypothesis
against which the predictions may be tested and that most
predictions cover a long period and the hypotheses evolve
before they can be tested (Kagan and Jackson, 1994). A
question then arises to what extent the model is superior
to a random occurrence model (time-independent). In
order to address this question, the term cMp of the ®rst
relation of Eq. (1) is ignored. By doing this, all the mainshocks are ®tted without any limitation (i.e., randomly).
This forms the Gutenberg±Richter relation for the mainshocks. Therefore, the empirical relation that describes the
time independent model is as follows:
log T 039M min 2 0:29 log mo 1 p
9
where p is different from one area to another (Table 1).
A direct way to check the superiority of the model against
the classical time-independent model is to apply both
models to a catalog and to compare the results (model probabilities) to real observations. This test can be made in an a
posteriori way to a reliable and complete sample of data.
Since the current data set is complete for M $ 6.0 during the
time interval from 1900 to 1995 in China, these two methods have been applied on this sample in the following way
(Papazachos et al., 1997a).
For each one of the seismogenic areas where at least one
earthquake of M $ 6.0 occurred since 1901, and for each
possible decade of the sample period, the model probability
for the occurrence of a mainshock with magnitude M $ 6.0
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Fig. 9. The success ratio vs the probability given by the time-dependent
model (black circles) and time-independent model (squares) for the Himalayan area (Area B). The dashed line expresses full success.
was calculated. Each period starts just after the occurrence
of the ®rst mainshock and ends 1 decade after the occurrence
of the last mainshock (e.g. 1901±1910, 1902±1911,¼1987±
1996, when the ®rst mainshock occurred in 1901 and the last
one in 1987 in this region). The model probabilities were
estimated based on the model Eq. (8) and lognormal distribution of T/Tt. A corresponding `yes' or `no' was assigned to each
decade if such a mainshock had occurred or not, respectively.
Then, the total range of the calculated model probabilities was
divided in equal intervals (0.0±0.09, 0.1±0.19¼) and all
decades were grouped in these intervals according to their
model probabilities. Finally, the success ratio of the number
of `yes' to the total number `yes 1 no' of decades was calculated for each group. The same procedure was repeated by
calculating probabilities on the basis of the time-independent
seismicity model (Gutenberg±Richter law for distribution of
magnitudes, Poisson law for distribution in time) that is
expressed in Eq. (9).
The results of this test are shown in Fig. 9, where the
success ratios are plotted vs probabilities, P10, for both the
time-dependent model (solid circles) and the time-independent model (squares with cross). The dashed line which
means full success is also shown. This ®gure evidences
the fact that the model probabilities are closer to the real
earthquake occurrence and cover a larger probability range.
In order to compare these results quantitatively, the linear
regression analysis was applied in both cases. A slope equal
to 1.04 (slope equal to 1 corresponds to the full success)
was obtained for the model probabilities. The linear hypothesis is accepted at the 0.99 signi®cance level
(t 9.79 . t7,0.005 3.50). For the time independent model
probability a slope equal to 1.05 was found and is rejected
even at 0.95 signi®cance level (t 2.24 , t2,0.05 2.92). It
105
Fig. 10. The number of the mainshocks predicted vs the mean number of
mainshocks in 1 decade for the 10 seismic areas marked by letters. The dash
line means that the actual number is equal to the predicted one.
is worth to note here the limited range of values obtained.
Therefore, this test shows the effectiveness of the regional
time predictable model and its superiority with respect to the
classical time-independent model for long interevent times
(Papazachos et al., 1997a, 1997b).
A second test has also been applied to examine whether the
calculated probabilities express the actual rate of earthquake
occurrence. As an estimation of the expected number of mainshocks with M $ 6.0 in each seismic area during the next
decade (1996±2005), the sum of the calculated probabilities,
SP10, can be considered for all seismogenic regions in each
seismic area. This sum can be compared with the average
number, l 10, of such observed earthquakes per decade, as
this number is deduced from the complete sample of data
available. This comparison can indicate the level of expected
seismic activity in the area, according to the model, with
respect to the mean seismic activity. The estimated values
are shown in Table 1 and plotted in Fig. 10, where the line is
the bisector. From this Fig. we can see that the number of
mainshocks predicted are close to the actual rates in almost
all the 10 areas. Exceptions are areas A and D where the sum of
the probabilities was found to be larger than the mean occurrence rate. This is probably due to an expected high active
period in these areas during the next decade.
3. Application of the model and results obtained
Based on Eq. (8) and the parameters q and m estimated
separately for each seismic area, the probabilities for the
occurrence of strong (M $ 6.0) earthquakes in the next 10
years, as well as the magnitude of the expected mainshock
can be calculated. The results obtained are shown in Table 2.
106
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2
Seismicity parameters (b, a, Mmax, mo) and expected strong mainshocks for each seismogenic region in the 10 areas of China territory. P10 is the model
probability for the occurrence of a mainshock with Ms $ 6.0 during the next 10 years and Mf is the most probable magnitude of the expected mainshock. The
last two columns give the year of occurrence and the cumulative magnitude a, M, of the mainshocks occurred in each seismogenic region
Region
Latitude
1
35.5
36.4
34.5
33.5
33.5
34.5
31.7
30.5
31.7
31.1
30.8
29.5
30.5
30.8
29.8
28.4
29.5
72.0
73.3
75.5
74.0
74.0
75.5
78.1
77.0
78.1
79.5
80.0
79.2
77.0
80.0
82.4
81.8
79.2
28.4
29.8
28.9
27.5
27.5
28.9
28.4
27.0
28.4
28.4
26.6
27.0
8
9
2
3
4
5
6
7
10
11
12
Longitude
b
Mmax
logmo
Mf
Year
M
3.58
0.93
6.0
23.52
9
5.7
1981-09-12
6.0
4.22
0.93
8.3
25.47
76
6.5
7.0
24.35
1
5.7
1905-04-05
1967-02-20
1980-08-23
1986-04-26
1962-07-14
1969-06-22
1986-07-16
1991-10-20
8.3
6.0
5.5
5.3
5.0
5.1
5.1
7.0
3.84
0.93
4.39
0.93
7.1
24.96
50
6.1
4.06
0.93
7.0
24.57
44
6.0
1916-08-28
1945-06-04
1953-02-23
1958-12-28
1980-07-29
1936-05-27
1954-09-04
1973-10-16
7.1
6.5
5.6
6.7
6.5
7.0
6.4
5.1
81.8
82.4
84.8
84.2
84.2
84.8
86.8
86.4
86.8
89.7
89.6
86.4
4.09
0.93
8.0
25.17
68
6.3
1833-08-26
1956-07-03
1974-03-24
8.0
5.7
6.2
4.08
0.93
8.3
25.33
76
6.4
89.6
89.7
93.0
93.2
4.33
0.93
7.5
25.13
64
6.3
28.7
29.8
28.2
27.3
27.0
29.8
30.8
29.5
28.2
93.0
94.2
95.5
94.7
93.2
94.2
95.3
96.8
95.5
4.43
0.93
7.3
25.11
53
6.1
1934-01-15
1960-08-12
1965-01-12
1971-12-04
1980-11-20
1990-01-09
1931-09-13
1941-01-21
1950-08-17
1954-02-23
1964-04-13
1985-10-13
1995-02-17
1947-07-29
1964-10-22
1985-08-01
8.3
5.0
5.7
5.7
6.1
5.1
6.5
6.8
5.8
6.0
6.2
5.0
5.7
7.3
6.7
5.7
26.6
28.4
28.7
27.0
4.37
0.93
7.0
24.88
47
6.0
29.5
27.8
27.6
28.2
26.1
27.6
27.8
27.2
26.1
96.8
97.4
95.7
95.5
95.9
95.7
97.4
97.5
97.5
4.57
0.93
8.6
25.99
32
5.9
1938-11-21
1950-10-08
1965-06-15
1981-10-24
1988-01-25
1992-02-06
1950-08-15
1987-01-09
6.0
6.6
5.0
5.7
5.6
5.7
8.6
5.0
4.41
0.93
7.6
25.26
68
6.3
1908-12-12
1950-08-22
1959-02-15
1962-09-22
1976-08-13
1984-11-28
7.6
6.3
5.7
6.4
6.3
5.7
a
P10(%)
107
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
Latitude
13
26.1
26.1
24.4
24.4
95.9
97.5
97.5
95.9
14
35.3
37.0
38.0
38.0
36.4
35.3
36.4
33.5
32.4
33.5
32.7
31.1
31.7
32.4
32.7
31.7
29.8
30.8
31.1
29.8
31.7
30.4
28.9
30.4
30.5
28.4
28.4
28.9
74.6
72.7
73.2
74.3
76.0
74.6
76.0
79.0
77.5
79.0
80.5
79.5
78.1
77.5
80.5
83.1
82.4
80.0
79.5
82.4
83.1
85.9
84.8
85.9
88.2
88.5
86.8
84.8
20
28.4
30.5
30.9
30.1
28.6
28.4
21
15
16
17
18
19
22
23
24
25
Longitude
b
Mmax
logmo
P10(%)
Mf
Year
M
4.40
0.93
7.5
25.20
56
6.6
3.93
0.93
6.7
24.27
13
6.0
1931-01-28
1962-02-21
1971-05-31
1981-08-17
1994-01-11
1950-08-20
1964-02-02
1982-07-02
1990-03-25
7.5
6.6
6.2
5.4
6.1
5.0
6.1
5.6
6.3
4.04
0.93
6.8
24.44
24
6.0
4.05
0.93
6.7
24.39
22
6.0
1951-08-26
1955-06-27
1963-04-12
1966-08-05
1975-01-11
1911-10-15
1966-03-06
1982-01-24
5.0
5.7
5.0
5.1
6.8
6.7
6.1
6.6
4.35
0.93
6.7
24.69
39
6.1
4.09
0.93
6.8
24.49
4
6.0
88.5
88.2
89.3
91.2
91.4
89.7
4.44
0.93
8.0
25.52
48
6.4
28.7
28.6
30.1
31.2
29.8
31.2
32.0
30.8
29.8
30.8
32.0
33.4
32.2
93.0
91.4
91.2
92.7
94.2
92.7
93.8
95.3
94.2
95.3
93.8
95.1
96.7
4.07
0.93
7.0
24.58
27
6.0
3.46
0.93
5.5
23.12
1913-03-06
1944-10-18
1957-04-14
1971-05-03
1918-02-05
1951-05-28
1958-11-24
1964-11-10
1970-02-27
1974-09-27
1988-09-03
1993-03-20
1901-04-21
1924-10-09
1935-05-21
1955-03-27
1980-02-22
1989-02-04
1992-07-30
1915-12-03
1951-12-03
1959-02-22
1968-01-13
1992-08-17
1959-11-18
1967-08-15
6.5
6.9
6.6
5.4
6.0
5.7
5.2
5.0
5.1
5.6
5.3
6.8
6.8
6.5
6.2
6.3
6.2
6.0
6.7
7.0
5.8
5.7
5.2
5.5
5.2
5.5
4.10
0.93
6.5
24.33
28
6.0
32.2
33.4
34.7
33.4
30.1
30.9
96.7
95.1
96.3
98.0
91.2
89.3
3.74
0.93
6.5
23.97
24
5.9
4.69
0.93
8.0
25.77
75
6.6
1950-08-26
1954-03-09
1961-12-04
1971-04-03
1985-01-16
1915-05-05
1977-12-16
1986-04-04
1989-04-13
1921-10-15
1925-01-12
5.2
5.8
5.9
6.6
5.1
6.5
5.3
5.1
5.4
6.2
6.5
a
±
±
108
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
26
27
28
29
30
31
32
33
34
35
36
Latitude
Longitude
a
b
Mmax
logmo
P10(%)
Mf
Year
M
1940-09-03
1951-11-18
1972-07-23
1977-05-28
1993-01-18
1955-08-04
1961-11-04
1971-05-23
6.3
8.1
6.0
6.3
6.3
5.0
5.5
6.1
1934-06-23
1959-04-27
1975-05-05
1983-06-15
1990-06-02
1994-06-03
1915-04-28
1950-09-19
1962-02-13
1992-02-03
1950-10-31
1966-03-14
1979-03-29
6.0
6.0
6.1
5.7
5.7
6.6
6.5
5.3
5.3
5.2
5.6
5.1
6.2
1923-10-20
1948-05-25
1960-05-03
1968-03-03
1979-11-06
1989-05-03
1951-03-17
1984-01-22
6.5
7.1
5.4
5.7
5.0
6.8
6.2
5.0
32.0
31.2
91.0
92.7
31.2
32.0
32.9
32.0
32.9
34.3
33.4
32.0
92.7
91.0
91.7
93.8
91.7
92.8
95.1
93.8
3.61
0.93
6.1
23.61
19
5.8
4.25
0.93
6.5
24.48
5
6.0
33.4
34.3
35.5
34.7
30.3
32.2
33.4
31.3
30.3
31.3
29.5
28.8
28.7
95.1
92.8
93.7
96.3
98.3
96.7
98.0
99.8
98.3
99.8
101.2
101.0
99.1
3.71
0.93
6.5
23.94
24
5.9
3.65
0.93
7.0
24.16
29
6.0
4.36
0.93
7.5
25.16
35
6.3
30.8
32.2
30.3
29.5
28.6
29.5
30.3
28.7
26.4
26.3
28.7
28.8
26.9
95.3
96.7
98.3
96.8
97.1
96.8
98.3
99.1
100.5
99.2
99.1
101.0
100.6
3.89
0.93
6.0
23.83
27
5.9
3.81
0.93
6.5
24.04
26
5.9
1921-051960-09-02
1986-02-06
6.5
5.7
5.1
4.22
0.93
7.5
25.02
59
6.4
28.7
26.3
26.1
27.2
27.8
28.6
24.1
26.3
26.4
24.4
99.1
99.2
97.5
97.5
97.4
97.1
99.7
99.2
100.5
101.1
3.86
0.93
6.5
24.09
35
6.0
1925-10-15
1933-06-07
1948-06-27
1961-06-27
1966-09-28
1976-09-03
1982-07-03
1993-07-17
1911-071950-08-22
6.0
6.2
6.4
6.1
6.1
5.4
5.4
5.9
6.5
6.1
4.11
0.93
7.0
24.62
53
6.4
21.5
24.1
24.4
21.7
100.5
99.7
101.1
102.3
4.54
0.93
6.7
24.88
26
6.4
1901-02-15
1925-03-16
1953-06-08
1963-04-23
1978-05-19
1986-03-13
1923-07-01
1942-02-01
1953-06-26
1965-07-03
1970-02-07
1973-08-16
6.5
7.0
5.0
6.0
5.6
5.5
6.5
6.7
5.7
6.1
6.2
6.7
109
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
Latitude
Longitude
a
b
Mmax
logmo
P10(%)
Mf
Year
M
1981-09-19
1993-01-27
1929-10-17
1941-10-31
1955-03-22
1966-09-19
1970-02-05
1976-05-29
1991-07-22
1923-06-22
1938-05-14
1941-05-16
1952-06-19
1984-04-24
1988-11-06
1913-081952-09-30
1962-02-27
1976-01-17
1988-01-10
1955-09-23
1964-11-20
1975-01-12
1993-08-14
6.0
6.5
6.9
6.2
6.2
5.6
5.7
7.2
5.3
7.1
6.0
7.4
6.5
6.0
7.6
6.0
6.7
5.6
6.7
5.7
6.9
5.2
5.6
6.1
37
23.5
24.4
26.1
26.3
24.1
97.8
97.5
97.5
99.2
99.7
4.68
0.93
7.0
25.19
41
6.3
38
21.5
23.5
24.1
21.5
98.6
97.8
99.7
100.5
4.81
0.93
7.3
25.49
28
6.3
39
29.5
28.8
27.4
26.9
26.9
24.4
26.4
26.9
26.9
24.7
24.7
26.9
27.4
26.6
25.0
23.2
24.4
25.0
23.2
101.2
103.0
102.6
101.9
100.6
101.1
100.5
100.6
101.9
102.3
102.3
101.9
102.6
104.1
104.0
101.6
101.1
104.0
104.0
4.28
0.93
7.5
25.08
52
6.4
4.25
0.93
6.9
24.70
34
6.4
4.17
0.93
8.0
25.25
68
6.6
1833-09-06
1927-03-15
1966-02-13
1985-04-18
8.0
6.2
6.3
6.3
4.50
0.93
7.3
25.18
40
6.3
38.3
36.9
38.0
38.2
39.0
35.2
36.9
37.6
36.0
35.2
36.0
34.3
33.5
32.4
32.7
33.5
34.3
33.6
31.7
32.4
33.6
33.1
32.5
30.4
31.7
77.8
75.4
74.3
74.5
76.6
77.3
75.4
76.6
78.5
77.3
78.5
80.2
79.0
81.4
80.5
79.0
80.2
82.1
83.1
81.4
82.1
83.4
84.7
85.9
83.1
3.04
0.93
7.0
23.55
1909-05-11
1913-12-21
1929-03-22
1940-04-06
1950-09-13
1965-05-24
1969-01-05
1980-06-18
1975-02-12
6.5
7.1
6.2
6.0
5.7
5.0
7.3
5.6
5.1
3.87
0.93
6.7
24.21
33
6.2
3.79
0.93
6.5
24.02
29
6.1
3.32
0.93
5.5
22.98
1925-12-07
1967-05-28
1980-02-14
1993-04-08
1914-10-09
1926-08-07
1953-01-08
1968-02-12
1950-08-17
1979-05-21
6.0
5.9
5.8
5.5
6.5
6.2
5.0
5.3
5.3
5.0
3.97
0.93
6.5
24.20
42
6.2
1955-01-29
1978-04-04
6.6
6.1
3.89
0.93
6.2
23.94
28
6.0
1947-02-10
1988-11-07
6.4
5.7
40
41
42
43
44
45
46
47
48
±
±
±
±
110
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
49
50
51
52
53
54
55
56
57
58
59
60
61
Latitude
Longitude
b
Mmax
logmo
P10(%)
Mf
Year
M
4.00
0.93
6.5
24.23
27
6.2
1935-01-03
1952-10-08
1961-12-08
1974-03-03
1986-06-21
1994-07-24
1908-08-20
1934-12-15
1963-01-22
1977-03-15
1980-06-04
1938-12-03
6.5
5.4
5.5
5.7
6.1
6.0
7.0
7.1
5.1
5.4
5.8
6.0
1902-08-31
1952-06-04
1956-03-05
1975-10-27
1993-06-14
1946-11-07
1973-11-22
1977-02-20
1986-07-07
6.8
5.2
5.7
5.2
5.1
6.2
5.1
5.7
6.1
1920-10-12
1948-02-13
1975-04-28
1987-04-10
1992-04-05
1952-04-02
1961-06-04
1977-01-14
1985-06-15
6.2
6.2
6.4
5.7
6.2
5.3
6.5
5.2
5.4
a
32.5
31.8
30.4
31.8
31.8
30.6
30.5
84.7
86.3
85.9
86.3
88.1
88.5
88.2
30.6
31.8
32.6
32.0
30.9
32.0
32.6
33.7
32.9
35.5
37.6
38.3
36.6
35.8
34.3
35.5
35.8
35.2
33.9
35.2
35.8
36.6
36.5
88.5
88.1
89.2
91.0
89.3
91.0
89.2
89.8
91.7
79.0
76.6
77.8
80.0
79.5
80.2
79.0
79.5
81.5
81.2
81.5
79.5
80.0
81.8
4.16
0.93
7.1
24.73
29
6.1
3.58
0.93
6.0
23.52
26
6.0
3.90
0.93
7.0
24.41
25
6.1
3.83
0.93
6.2
23.88
29
6.1
4.17
0.93
6.3
24.28
30
6.2
33.1
33.9
35.2
35.0
34.3
33.7
34.3
83.4
81.2
81.5
82.5
84.4
86.0
84.4
35.0
84.4
87.2
84.7
83.4
84.4
86.0
86.3
84.7
86.0
87.2
88.5
88.5
89.8
89.2
88.1
86.3
91.7
89.8
90.9
92.8
82.5
81.5
81.8
3.79
0.93
6.5
24.02
29
6.0
0.93
5.5
3.79
0.93
6.0
23.73
29
6.0
1960-01-31
1973-09-08
1985-10-04
5.0
6.1
5.3
4.00
0.93
6.5
24.23
31
6.1
1950-12-29
1965-06-18
1977-11-18
5.7
5.8
6.6
4.18
0.93
6.5
24.41
30
6.1
1952-09-14
1981-06-10
1986-08-21
5.8
6.2
6.7
3.67
0.93
5.8
23.50
±
1980-10-07
1989-10-08
5.8
5.4
35.8
34.7
32.5
33.1
34.3
33.7
31.8
32.5
33.7
34.7
34.2
34.2
33.7
32.6
31.8
31.8
32.9
33.7
35.0
34.3
35.0
35.2
36.5
82.5
±
111
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
Latitude
Longitude
36.8
35.8
33.7
34.7
35.8
35.0
34.7
35.8
36.6
35.8
35.8
36.8
37.5
36.6
36.6
37.5
38.2
37.4
35.8
36.6
37.4
36.7
35.0
35.8
36.7
36.2
34.3
35.0
36.2
35.5
35.5
36.2
37.2
36.6
36.2
36.7
37.7
37.2
36.7
37.4
38.2
37.7
37.4
38.2
39.0
38.2
34.7
35.5
36.6
35.9
33.4
34.7
35.9
35.5
34.8
32.0
33.4
34.8
33.1
30.3
32.0
33.1
31.1
82.6
84.4
89.8
87.2
88.5
90.9
87.2
84.4
86.0
88.5
84.4
82.6
84.0
86.0
86.0
84.0
85.5
87.9
88.5
86.0
87.9
89.8
90.9
88.5
89.8
91.6
92.8
90.9
91.6
93.7
93.7
91.6
92.5
94.6
91.6
89.8
91.0
92.5
89.8
87.9
89.8
91.0
87.9
85.5
87.5
89.8
96.3
93.7
94.6
97.5
98.0
96.3
97.5
99.0
99.5
99.2
98.0
99.5
100.7
100.6
99.2
100.7
101.9
b
Mmax
logmo
P10(%)
Mf
Year
M
4.11
0.93
6.2
24.16
25
6.2
1920-05-02
1946-02-20
1994-08-14
6.4
6.0
6.0
4.07
0.93
6.9
24.52
46
6.3
4.34
0.93
7.2
24.96
28
6.1
1951-10-11
1965-01-21
1973-07-14
1985-05-20
1924-07-12
1960-12-11
1991-06-17
5.0
5.5
6.9
6.3
7.4
5.5
5.3
2.95
0.93
5.0
22.32
±
1963-05-07
5.0
3.88
0.93
6.0
23.82
6.1
1959-11-11
1966-10-14
6.0
6.0
3.74
0.93
5.7
23.51
±
±
1980-03-07
1989-05-14
5.6
5.7
3.56
0.93
5.7
23.33
±
±
1952-10-01
1980-07-13
1986-12-21
5.0
5.7
5.3
3.42
0.93
5.5
23.08
±
±
1994-12-28
5.5
3.51
0.93
5.6
23.22
±
±
1994-11-28
5.6
4.09
0.93
6.8
24.49
16
6.1
4.72
0.93
6.9
25.17
48
6.4
1933-09-26
1957-08-23
1963-08-12
1993-10-02
1902-11-04
1963-04-19
6.7
5.0
5.1
6.8
6.9
6.9
4.63
0.93
7.5
25.43
66
6.6
1936-01-07
1971-03-24
7.5
6.4
4.09
0.93
7.4
24.83
29
6.1
1947-03-17
1961-05-18
7.4
5.2
4.56
0.93
7.5
25.36
45
6.3
1904-08-30
1919-05-29
1923-03-24
1967-08-30
7.5
6.4
7.1
6.1
a
±
34
112
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
Latitude
Longitude
77
31.1
29.4
28.8
29.5
30.3
27.4
29.4
29.4
28.6
26.6
101.9
103.2
103.0
101.2
100.6
102.6
103.2
104.6
104.8
104.1
24.4
25.0
26.6
28.6
22.5
23.2
25.0
24.4
22.5
24.4
23.6
21.7
23.6
24.0
23.3
22.2
21.6
21.7
24.0
26.8
25.6
23.3
22.2
23.3
25.6
24.2
24.2
25.6
27.8
26.6
38.2
39.0
39.7
38.8
37.2
37.7
38.2
38.8
38.4
36.6
37.2
38.4
37.7
36.6
37.7
37.0
35.9
37.0
78
79
80
81
82
83
84
85
86
87
88
89
90
b
Mmax
logmo
P10(%)
Mf
Year
M
4.35
0.93
7.7
25.25
85
6.8
1972-02-06
1932-03-07
1941-06-12
1955-04-14
1975-01-15
1989-06-09
1917-07-31
1936-04-27
1959-03-11
1966-10-11
1970-07-31
1974-05-11
1994-12-30
1955-05-27
1973-08-02
1985-12-02
7.3
6.0
6.0
7.4
6.2
5.6
7.3
6.9
5.3
5.1
5.4
6.8
6.1
5.0
5.2
5.4
4.55
0.93
7.3
25.23
58
6.6
107.5
104.0
104.1
104.8
107.0
104.0
104.0
107.5
107.0
107.5
111.0
110.5
111.0
113.8
114.6
115.6
113.0
110.5
113.8
116.5
118.0
114.6
115.6
114.6
118.0
119.5
119.5
118.0
121.6
122.8
89.8
87.5
89.5
91.7
92.5
91.0
89.8
91.7
93.3
94.6
92.5
93.3
95.6
94.6
95.6
98.5
97.5
3.43
0.93
6.0
23.37
±
±
3.62
0.93
5.7
23.39
±
±
1962-04-23
1982-10-27
5.5
5.7
3.86
0.93
6.7
24.20
22
6.0
1936-04-01
1958-09-25
1977-10-19
6.7
5.7
5.0
3.78
0.93
6.4
23.95
19
6.0
1911-05-15
1969-07-26
1986-01-28
6.0
6.4
5.2
3.70
0.93
6.1
23.70
21
6.0
1962-03-19
1982-02-25
1987-08-03
6.1
5.0
5.4
4.29
0.93
7.2
24.91
24
6.0
3.54
0.93
8.0
24.62
±
±
3.77
0.93
5.7
23.54
±
±
3.93
0.93
6.3
24.04
22
6.1
1906-03-28
1918-02-13
1968-04-01
1995-02-25
1960-07-21
1978-08-10
1985-11-28
1992-02-18
1960-11-17
1979-12-02
1991-01-06
1994-09-07
1976-01-02
1990-01-14
6.2
7.3
5.2
5.6
5.0
5.2
5.0
5.6
5.4
5.6
5.1
5.7
6.3
6.1
3.21
0.86
6.0
23.52
19
6.0
1952-10-06
1993-09-05
6.0
5.5
3.88
0.86
6.9
24.77
26
6.1
3.94
0.86
7.0
24.89
20
6.1
1957-05-04
1962-05-21
1972-08-30
1977-01-19
1985-08-12
1991-09-02
1952-03-21
5.5
6.9
5.7
5.9
5.4
5.5
5.0
98.5
a
113
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
91
92
93
94
95
96
97
98
99
100
101
102
103
Latitude
Longitude
36.4
35.5
35.5
35.9
33.4
35.5
35.5
34.0
33.4
34.0
32.8
31.1
32.8
35.5
36.4
34.6
33.7
29.4
29.4
31.1
31.0
31.1
32.8
33.7
33.2
31.0
101.0
100.5
99.0
97.5
100.5
99.0
100.5
101.8
100.5
101.8
102.8
101.9
102.8
100.5
101.0
104.0
103.5
104.6
103.2
101.9
104.5
101.9
102.8
103.5
105.5
104.5
33.7
34.6
35.7
35.5
33.2
34.6
36.4
37.2
35.7
a
b
Mmax
logmo
P10(%)
±
Year
M
1990-04-26
7.2
±
1950-06-18
1958-09-11
1978-02-21
5.0
5.1
5.1
Mf
3.07
0.86
5.1
22.80
3.48
0.86
6.0
23.79
22
6.0
1935-07-26
1952-11-01
1970-09-05
6.0
6.0
5.8
3.34
0.86
6.2
23.78
17
6.0
1974-09-23
1987-01-08
5.6
6.2
3.56
0.93
6.0
23.50
19
6.0
1962-07-01
1967-01-24
1970-02-24
5.1
5.5
6.0
4.67
0.93
8.0
25.75
56
6.6
103.5
104.0
104.7
106.6
105.5
104.0
101.0
102.2
104.7
3.34
0.86
8.0
24.93
32
6.4
1879-07-01
1933-08-25
1952-11-04
1960-11-09
1973-08-11
1976-08-16
1989-09-22
1936-08-01
1961-10-01
1987-10-25
8.0
7.3
5.7
6.8
6.1
7.1
6.8
6.0
5.8
5.5
3.41
0.86
7.0
24.36
20
6.0
36.4
37.0
38.2
37.2
37.2
38.2
39.1
38.2
101.0
98.5
99.5
102.2
102.2
99.5
100.3
103.0
2.96
0.86
5.4
22.89
1936-02-07
1957-07-18
1964-05-31
1968-12-22
1995-07-22
1952-01-27
1986-09-17
6.7
5.1
5.0
5.4
6.1
5.0
5.4
3.78
0.86
7.7
25.18
49
6.4
38.9
40.1
39.9
39.1
38.2
38.9
39.7
40.8
40.1
37.7
38.9
38.2
37.0
97.0
98.0
100.6
100.3
99.5
97.0
94.2
95.7
98.0
95.6
97.0
99.5
98.5
3.51
0.86
7.2
24.59
26
6.2
1927-05-23
1955-05-04
1958-11-30
1978-08-16
1986-08-26
1962-08-01
1969-10-17
1975-01-04
1993-10-26
7.7
5.0
5.1
5.0
6.4
5.4
5.1
5.3
6.4
3.69
0.86
7.5
24.96
35
6.4
1932-12-25
1951-12-27
1989-09-21
7.5
6.1
5.3
3.41
0.86
6.5
24.04
23
6.1
37.7
38.4
95.6
93.3
3.12
0.86
5.7
23.24
1927-03-16
1930-07-14
1938-08-23
1957-03-23
1980-04-18
1980-06-01
6.0
6.5
6.0
5.0
5.2
5.6
±
±
±
±
114
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
Latitude
Longitude
39.7
38.9
40.3
39.7
38.4
38.8
39.7
38.2
39.1
39.9
39.8
35.7
37.2
38.2
37.7
35.7
37.7
37.6
35.5
94.2
97.0
91.8
94.2
93.3
91.7
89.5
103.0
100.3
100.6
103.2
104.7
102.2
103.0
104.8
104.7
104.8
106.5
106.6
38.2
39.8
39.6
37.7
37.7
39.6
39.3
37.6
39.6
40.3
41.5
40.3
39.3
40.3
39.7
41.3
42.3
41.3
42.7
43.2
42.3
43.2
42.7
44.2
44.7
45.1
114
115
104
105
106
107
108
109
110
111
112
113
b
Mmax
logmo
P10(%)
Mf
Year
M
3.48
0.86
6.5
24.11
20
6.0
1922-10-17
1977-10-20
1987-02-26
6.5
5.1
6.4
3.46
0.86
7.0
24.41
14
5.7
1954-02-11
1989-09-04
7.0
5.1
3.16
0.86
6.2
23.60
1
5.6
1959-01-31
1990-10-20
5.2
6.2
3.90
0.86
8.4
25.75
17
5.9
103.0
103.2
104.8
104.8
104.8
104.8
106.7
106.5
104.8
105.0
106.5
107.6
106.7
91.8
89.5
88.1
90.3
88.1
86.9
89.2
90.3
89.2
86.9
85.6
86.1
88.2
3.54
0.86
7.0
24.49
15
5.8
1920-12-16
1959-01-31
1970-12-03
1982-04-14
1989-11-02
1954-07-31
8.4
5.2
5.5
5.7
5.4
7.0
3.56
0.86
8.0
25.15
47
6.3
1962-12-18
1971-06-28
1987-08-10
5.7
5.1
6.0
3.36
0.86
6.2
23.80
9
5.7
1959-10-06
1976-09-23
1991-01-13
5.0
6.2
5.8
3.39
0.86
6.4
23.96
11
6.0
1983-10-06
1987-12-22
5.5
6.4
3.35
0.86
5.6
23.40
±
1953-11-29
1983-12-15
1991-06-06
5.0
5.2
5.8
3.83
0.86
6.6
24.52
45
6.2
42.7
41.0
42.8
44.2
86.9
84.4
84.0
85.6
4.09
0.93
7.1
24.66
42
6.2
42.8
42.8
41.0
40.7
42.3
81.7
84.0
84.4
81.2
80.2
4.32
0.93
7.3
25.00
68
6.5
1907-05-13
1934-08-07
1953-04-26
1965-11-13
1980-11-06
1987-10-06
1906-12-23
1927-09-23
1960-11-30
1966-07-22
1972-04-09
1988-05-26
1993-02-03
1916- 1939-02-23
1949-02-24
1963-12-18
1970-11-29
1976-01-10
1979-03-29
1987-01-06
1995-05-12
6.0
6.0
6.2
6.6
5.9
5.0
7.1
6.7
5.0
5.0
5.7
5.2
5.7
6.0
6.0
7.3
5.8
5.0
5.8
6.0
6.2
5.1
a
±
115
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
Latitude
b
Mmax
logmo
P10(%)
Mf
Year
M
116
41.5
42.3
40.7
39.8
78.0
80.2
81.2
78.9
4.46
0.93
6.7
24.80
23
6.3
75.8
75.8
79.5
80.2
78.0
76.6
75.9
78.0
78.9
4.25
0.93
7.0
24.76
43
6.4
1915-12-17
1959-06-28
1969-02-12
1978-03-12
1987-01-24
1991-02-25
1938-06-21
1969-02-12
1978-03-25
1990-11-12
6.5
6.7
6.7
5.5
6.4
6.7
6.7
5.2
7.0
6.3
117
41.5
43.0
43.3
42.3
41.5
39.0
40.8
41.5
39.8
4.53
0.93
7.3
25.21
76
6.6
38.2
40.0
40.8
39.0
74.5
74.0
75.9
76.6
4.89
0.93
7.6
25.74
58
6.4
120
38.0
39.5
40.0
38.2
38.0
73.2
72.3
74.0
74.5
74.3
4.53
0.93
7.2
25.15
44
6.2
121
42.8
42.3
43.3
45.2
44.3
42.8
42.8
45.2
44.7
81.7
80.2
79.5
81.0
83.0
84.0
81.7
83.8
86.1
4.10
0.93
7.5
24.90
36
6.0
4.45
0.93
8.0
25.53
72
6.5
45.2
47.0
46.2
44.3
46.2
47.0
48.7
47.7
46.2
48.3
48.7
46.8
47.7
48.7
48.3
46.2
45.1
44.7
45.2
81.0
83.0
84.8
83.0
84.8
83.0
85.4
86.8
89.5
88.6
90.0
91.1
86.8
85.4
88.6
89.5
88.2
86.1
83.8
3.49
0.93
6.0
23.43
8
5.6
1902-08-31
1953-07-10
1961-04-14
1970-07-29
1977-12-19
1986-04-26
1995-05-15
1902-08-22
1919-07-24
1944-09-28
1955-04-15
1969-09-15
1978-01-08
1985-08-23
1918-12-01
1950-07-06
1963-10-16
1974-08-11
1987-08-06
1994-10-03
1921- 1951-10-31
1958-12-21
1967-01-14
1970-11-16
1812-03-08
1944-03-10
1955-04-24
1966-07-06
1973-06-03
1983-06-29
1990-10-25
1995-05-02
1932-09-11
1962-03-28
1975-04-23
7.3
6.2
7.0
6.1
6.2
5.6
5.7
7.6
6.5
6.8
7.2
5.9
6.1
7.4
6.5
5.3
6.7
7.3
5.4
5.5
6.5
5.4
6.7
5.0
5.5
8.0
7.1
6.6
5.0
6.0
5.3
5.8
6.1
6.0
5.0
5.0
119
3.61
0.86
6.8
24.43
2
5.8
1982-03-20
1990-06-14
5.0
6.8
3.99
0.86
7.7
25.39
60
6.4
1931-08-11
1970-09-19
1987-09-19
7.7
5.2
6.2
118
122
123
124
125
126
Longitude
a
116
C. Qin et al. / Journal of Asian Earth Sciences 19 (2001) 97±128
Table 2 (continued)
Region
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
Latitude
Longitude
46.2
44.3
46.2
46.8
44.8
44.3
43.2
45.1
46.2
42.8
44.3
44.8
43.3
42.3
43.2
44.3
42.8
40.3
41.5
41.5
39.7
39.7
41.5
41.0
39.3
39.3
41.0
40.8
39.0
37.5
39.3
39.0
37.2
34.5
37.8
37.5
37.2
34.0
34.0
37.2
36.7
33.8
37.2
39.0
38.7
36.7
39.0
40.8
40.5
38.7
37.8
39.7
39.3
37.5
36.7
38.7
40.5
40.5
39.0
43.8
40.0
39.0
40.5
84.8
91.3
89.5
91.1
93.0
91.3
89.2
88.2
89.5
92.7
91.3
93.0
94.3
90.3
89.2
91.3
92.7
107.6
106.5
109.5
109.5
109.5
109.5
113.0
112.7
112.7
113.0
115.0
114.4
112.0
112.7
114.4
113.6
110.0
110.0
112.0
113.6
112.5
112.5
113.6
115.9
115.2
113.6
114.4
116.0
115.9
114.4
115.0
116.5
116.0
110.0
109.5
112.7
112.0
115.9
116.0
116.5
120.0
120.0
125.4
126.0
120.0
120.0
b
Mmax
logmo
P10(%)
Mf
Year
M
0.86
6.5
24.23
25
6.0
1933-02-13
1954-02-19
1980-12-16
6.5
5.7
5.8
0.86
7.5
3.84
0.86
7.2
2