STUDI KERENTANAN LONGSOR PADA RUAS JALAN

STUDI KERENTANAN LONGSOR PADA RUAS JALAN
DEPOSISI INTRUSI BATUAN BEKU INTERAKSI STRUKTUR SESAR
Agustinus T1, Lawalenna Samang2, Herman Parung3, and Tri Hariyanto4
ABSTRAK
Peristiwa tanah longsor pada ruas jalan didaerah Parangloe menuju ke kota Malino yang sering terjadi pada waktu
musim hujan dengan curah hujan yang cukup tinggi sudah perlu menjadi perhatian untuk diteliti terutama dibeberapa
titik dari khususnya dari Km +62 kearah kota Malino yang terletak di kecamatan Parangloe. Tujuan dari penelitian ini
dapat ditinjau dari pengaruh kontrol topografi yang memiliki variasi dan kondisi geologi yang tersusun oleh tubuh tanah
atau batuan residual vulkanik berumur Pliosen-Miosen, berasal dari hasil aktivitas vulkanik terdiri dari tanah dan batuan
tufa, breksi, tufa berlapis, batuan beku serta keterkaitannya dengan adanya tubuh intrusi batuan beku dan struktur sesar.
Ditunjang dengan metodologi startigrafi terukur, pemboran dan hasil dari pengamatan laboratorium yang terdiri dari
petrografi, diharapkan dari penelitian ini dapat menjelaskan bahwa longsor yang terjadi di daerah Parangloe ada
hubungan korelasi Interaksi sesar dan intursi batuan beku terhadap tubuh tanah atau batuan vulkanik.
Kata Kunci : Longsor, Tanah dan Batuan Vulkanik, Intrusi, Sesar, Parangloe.

1
2
3
4

1

Post Graduate Student of Civil Engineering Department, Hasanuddin University of Makassar Perintis Kemerdekaan Street Km10, Indonesia, Email: haerany_sirajuddin@yahoo.com
2
Lecturer of Physics Department, Hasanuddin University of Makassar Perintis Kemerdekaan Street Km-10, Indonesia, Email:
dahmaduh@gmail.com
3
Lecturer of Engineering Geology Department, Hasanuddin University of Makassar Perintis Kemerdekaan Street Km- 10 ,
Indonesia,, Email: mudimran@yahoo.com
Lecturer of Civil Engineering Department, Hasanuddin University of MakassarPerintis Kemerdekaan Street Km-10 , Indonesia,
Email: athaha_99@yahoo.com

Pendahuluan
Pulau Sulawesi
Terbentuk dari
akumulasi micro
lempeng yang terurai
dari berbagai variasi
sumber fragmen dari
lempeng Asia,Pasific
dan Australia (gambar

1). Sejak itu Formasi
yang terbentuk
merupakan kompleks
geologi

stability
disturbance
and threat of an
earthquake at any time,
will lead to vulnerable
coastal area. Further
studies are needed to
support an integrated
management of the
coastal area.

Since its formation in
the Tertiary period to
the present, it
consequently produces

continuous complex
geological and tectonic
phenomena. Due to the
insistence of influence /
pressure by the three
major plates, it
becomes a very
vulnerable condition
and includes one of the
most active islands in
the world.
Fenomena Geologi
dan tektonik daerah
yang tersusun oleh
Parangloe
Vulkanik
yang terdiri dari oleh
Tufa tidak berlapis dan
tufa berlapis breksi,
intrusi batuan beku,

geological
structures
(joint and fault), and
the sign of tectonic
uplift; coast terrace,
abrasion
terrace,
Quarter coral
reef
outcrops, alluvial flat
and earthquakes for
periodic activeness in
every 15 to 30 years.
Geological condition
and tectonic uplift,
causing
shoreline
changes
advancing
towards the sea, the

occurrence of abrasion,
sedimentation
and
uplift,
threatened
marine biota (benthos),
shallower seabottom in
the front of port of
Parepare,
bedrock

area
and
its
surroundings
which
also covers the area of
two estuaries (Karajae
River and Bojo River)
with the recording date

of June 12, 2002 and
June 17, 2011. Image
processing
of
LANDSAT 7 ETM +
utilizes
statistical
software
ERMapper
7.0 and ArcGIS 9.3 to
digitize
shoreline
change map.

uncovering Quaternary
coral reefs and also
Quaternary alluvial flat,
including emergence
coast, Johnson, 1919
(Fig. 2 and Fig. 3).

Lithology
The rocks found in
Lumpue
coast
(Sukamto,
1982)
consists
of
lava,
volcanic breccia, tuff
(Upper
Miocene),
Quaternary sandstones
and alluvial

RESULTS
AND
DISCUSSIONS
Results
and

discussions will be
based on geological
coastal
conditions,
analysis by Landsat 7
ETM +, tectonic and
paleo-bathymetry and
coastal vulnerability.
Coastal Geology
Fig. 1 Study
location map.

area

METHODS
In this study, direct
observation has been
conducted into the field
to see the geological
condition of the

coastal
area
including erosion and
sedimentation, tectonic
and paleo-bathymetry.
For paleo-bathymetry
measurement has been
done manually by
observing
and
measuring the position
of Quaternary coral
reefs to average sea
level (mean sea - level).
In addition, a map
image of LANDSAT 7
ETM + is used which
includes Lumpue coast

Physiography

The coast is defined
as the areas including
land
and
sea
interaction.
Lumpue
coastal area is hilly and
rugged coastal base, as
a result from tectonic
formation, geological
structure and abrasion
(maturity
abrasion)
which
reveal
the
winding
irregular
shoreline.

Erosion
and
sedimentation events
occur in Lumpue coast,
according to Shepard
(1973) classification,
most of the Lumpue
coastal (sedimentation
area) including the
dominant primary coast
and
the
coastal
abrasion known as a
secondary coast. From
the aspects of tectonics,
uplift in Lumpue coast
characterized by the
coastal terrace and

deposits.
Lava,
volcanic breccia and
tuff
are
trachytic
sourced
from
the
eruption of Parepare
volcano
(Kaharuddin,
2007)
with Lumpue coastal
caldera, alluvial and
sandstones
are
Quaternary sediments
from the terrestrial
erosion processes.
METHODS
In this study, direct
observation has been
conducted into the field
to see the geological
condition of the
coastal
area
including erosion and
sedimentation, tectonic
and paleo-bathymetry.
For paleo-bathymetry
measurement has been
done manually by
observing
and
measuring the position
of Quaternary coral
reefs to average sea
level (mean sea - level).

Tectonics and Paleo-bathymetry

In addition, a map
image of LANDSAT 7
ETM + is used which
includes Lumpue coast
area
and
its
surroundings
which
also covers the area of
two estuaries (Karajae
River and Bojo River)
with the recording date
of June 12, 2002 and
June 17, 2011. Image
processing
of
LANDSAT 7 ETM +
utilizes
statistical
software
ERMapper
7.0 and ArcGIS 9.3 to
digitize
shoreline
change map.

the aspects of tectonics,
uplift in Lumpue coast
characterized by the
coastal terrace and
uncovering Quaternary
coral reefs and also
Quaternary alluvial flat,
including emergence
coast, Johnson, 1919
(Fig. 2 and Fig. 3).

Fig. 2 Coastal terrace
(X) and abrasion flat
(Y), the caldera cliff on
the Lumpue coast.

Lithology
The rocks found in
Lumpue
coast
(Sukamto,
1982)
consists
of
lava,
volcanic breccia, tuff
(Upper
Miocene),
Quaternary sandstones
and alluvial

Fig.
3
Uplifted
Quaternary coral reefs
above sea level in the
Dutungan area.

RESULTS
AND
DISCUSSIONS
Results
and
discussions will be
based on geological
coastal
conditions,
analysis by Landsat 7
ETM +, tectonic and
paleo-bathymetry and
coastal vulnerability.
Coastal Geology
Physiography
The coast is defined
as the areas including
land
and
sea
interaction.
Lumpue
coastal area is hilly and
rugged coastal base, as
a result from tectonic
formation, geological
structure and abrasion
(maturity
abrasion)
which
reveal
the
winding
irregular
shoreline.
Erosion
and
sedimentation events
occur in Lumpue coast,
according to Shepard
(1973) classification,
most of the Lumpue
coastal (sedimentation
area) including the
dominant primary coast
and
the
coastal
abrasion known as a
secondary coast. From

deposits.
Lava,
volcanic breccia and
tuff
are
trachytic
sourced
from
the
eruption of Parepare
volcano
(Kaharuddin,
2007)
with Lumpue coastal
caldera, alluvial and
sandstones
are
Quaternary sediments
from the terrestrial
erosion processes.

RESULTS
AND
DISCUSSIONS
Results
and
discussions will be
based on geological
coastal
conditions,
analysis by Landsat 7
ETM +, tectonic and
paleo-bathymetry and
coastal vulnerability.

X
Y

Haerany Sirajuddin, et al.
apparently lying along
Lumpue Coastal area
consist of sand and
gravel particularly from
stream sediment and
several other small
rivers (Fig. 4).

shoreline. This shows
that the sedimentation
rate (man made and
natural processes) is
greater than the mass of
sediment removal, so
even if the abrasion
occurs,
the
resedimentation process
still takes place in the
Lumpue coastal area. It
is clear
that the
shoreline
grows
seaward (Fig. 5).

Fig. 4 Sand deposit at
Lumpue coast.
Landsat 7
Analysis
Geological structure
Geological
structures that appear
in the Lumpue coast
area are join and fault.
The join in the form of
open
and
closed
irregular joint, while
the fault through Bojo
River and the east-west
trending and in Karajae
River in the north, both
are dextral slip fault.
.
Abrasion
and
sedimentation
Apparent abrasion
on trachytic lava can be
seen either at Lumpue
coastal area or at Ujung
Lero peninsula. The
nature of acid rock is
not resistant to sea
water waves (alkaline),
consequently causing
an increased the rate of
abrasion,
especially
during the west season,
from January to April
every year. Sediments
from Karajae River and
Bojo
River
are

ETM

+

Interpretation
of
shoreline changes
based on Landsat
7 ETM + from year of
2002 and 2011 are
combined with field
data, indicating that the
shoreline change is
dominated by the rapid
advancement of the
shoreline
seaward
along the 6-13 meters,
covering southern part
of Lumpue coastal area
(the
Lojie
coast,
Lapakaka
coast),
Karajae estuary and its
surrounding. Changes
of coastal area are
causing
by:
(1)
sedimentation is about
36491.24
m2;
(2)
abrasion is about
40458.95 m2; and (3)
reclamation is about
61847.24 m2. Based on
the calculation above,
the natural process of
abrasion
is
more
extensive (bigger) than
the area of deposition.
In reality, there is an
advance
of
the

Fig. 5 Shoreline change
map of Lumpue coast.

Tectonics and Paleobathymetry

Tectonics and Paleo-bathymetry

The development of
Sulawesi
regional
tectonic affected by
divergent
tectonic
activity of the Pacific
plate moves westward,
urged the island of
Sulawesi, produce large
fault
trending
southeast–northwest
known as Walanae
Fault accompanied by
small
fault,
rocks
deformation, up-lift of
the coastal base and
coral reefs as well as
abrasion rate increasing
(Kaharuddin, 2007).
The Phenomena of
Quaternary tectonics
Quaternary tectonic
phenomena that appear
in the coastal areas
surrounding Lumpue
such
as
abrasion
terrace, coast terrace
(sand), alluvial flat,
rocks jointing, lifting of
coral reefs and the
earthquake. The details
can be mentioned as
follows:
1. Abrasion
terrace
contained in lava
rocks,
volcanic
breccia and tuff in
Lumpue
coast,
hillside of Parepare
and Tana Malie at
Ujung
Lero
peninsula,
shows

2.

cliff and abrasion
flat (Figure-2). The
forming of the
abrasion terrace as a
result of vertical uplift of a vertical of
at least 5 times as
much (of a number
of terrace exposed);
There are Lumpue
coast terrace which
composed by the
steps
of
sand
sediment
that
extends parallel to
the shoreline;

is an active seismic
lines of WalanaeMajene having a
return period of
between 15 to 30
years (Kaharuddin,
2007).

3. Alluvial

4.

5.

6.

flat
occupies Lumpue
plain and Parepare
city;
Joints on rock,
cracks in rocks that
are not regular and
high density as the
impact of rock
deformation
and
two faults through
this area;
Uplift of coral reef.
Regionally, the west
coast of Sulawesi,
including Lumpue
coast, coral reefs are
emerging in the
form of islands
above the sea level
around 0.5 to 4
meters (Figure-3);
Earthquake
in
Parepare (Lumpue)

Paleo-bathymetry
Manually
Paleobathymetry
measurement aimed to
determine the presence
of tectonic uplift and
sea-level change which
impacts the shoreline
changes.
This
measurement is done
by
observing
and
measuring the position
of the Quaternary reef
on mean sea level. This
method is based on the
assumption that coral
reefs flourish at a depth
of at least 5 meters
below sea level. A long
the Lumpue coast and
Dutungan coast at the
south, there are reefs
outcrop up to ± 50 cm
above sea level now.
According to De Klerk
(1982), any increase in
the base 1 meter reef
takes
1000
years.
Accordingly, the age of
the coastal basement is
now exposed in the
form of land about
5500 years which was
once a shallow sea with
a depth of ± 5.5 to 6
meters. De Klerk has
conducted research on
the coral reefs of the
C14 dating and changes
in sea level due to
tectonic uplift. It shows
that from 7000-4500
years ago there was an
increase in sea level of
about 5 meters, and up
to 1500 years ago there
was a decrease in sea
level due to the uplift
sea basement (Fig. 6).
Fig. 6 Sea level
fluctuation curve of in

Haerany Sirajuddin, et al.
the Quaternary era ( De
Klerk , 1982) .
Coastal Vulnerability
Based on Tectonics and
Shoreline Change
Tectonic activity in
the form of rock layers
up-lift
can
make
intensive more erosion
processes on the earth's
surface. The results of
erosion
will
be
deposited
and
distributed around the
coast in the form of
alluvial deposits, so
that the shoreline will
advance into the sea.
On the other hand,
coastal areas lifting
causing elevated wave
activity
to
work
optimally eroded rocks
and coastal sediment
material. If sediment
supply is smaller than
the wave energy, there
will
be
abrasion
causing
landward
retreat of the shoreline,
as was the case in most
Lumpue
coastal.
Tectonic activity can
also
cause
the
condition of the rock
layers
in
Lumpue
coastal areas become
susceptible
to
weathering and sea
water erosion. This is
shown in igneous lava
and volcanic breccia
that
experienced
intensive abrasion (Fig.
7).

Fig. 7 High abrasion of
lava
and
volcanic
breccia on northern
side
the
Lumpue
caldera.
Visually,
the
vulnerability of the
coast due to the
influence of tectonic
uplift and shoreline
change, namely:
a. Up-lift
of
basement
coastal
and
sediment
accumulation,
causing threat to
the
port
of
Parepare
and
benthic
organisms;
b. Abrasion
activities more
intensified work
in line with the
increased
of
wave activity,
result due to uplift;
c. Geological
structure zone is
mainly the fault
and joint are
vulnnerable to
physical
changes,
rock
resistance
weakened,
vulnerable
to
earthquakes and
mass
movement;

d. Unconsolidated
sediment
of
coastal lithology
and less massive
are vulnerable to
abrasion,
soil
mechanics
aspects (bearing
capacity) as well
as every time
happen
earthquake
at
Parepare city; It
is supported by
the
evidence
discovered by
Kaharuddin
(2007).
e. In analysis of
Landsat
7
ETM+ images
shows
that
interaction
between
sedimentation
and erosion are
very high, but
the
rate
of
deposition
greater
compared with
the effects of
abrasion. This
resulted in the
sorting
and
distribution of
sedimentary
material
less
than perfect so
that low bearing
capacity.
CONCLUSIONS AND
RECOMMENDATION
S
1. Conclusions
a. Geology Conditions
of Lumpue coast has
hilly
morphology,
plains and irregular
shoreline - including a
primary coastal type
and
emergence,
composed of lava,
volcanic breccias, tuffs
and alluvial. It affected

by the fault structure,
joint and abrasion.
b. Analysis of Landsat
7
ETM+
images
showed abrasion wider
area (40458.95 m2)
than the sedimentation
area (36491.24 m2), but
that is accompanied by
re-sedimentation
so
shoreline
changes
along
the
sea
advancing toward 6-13
meters during 20022011.
c.Tectonics and paleobathymetry
- Tectonic uplift
indicated by the
exposure terrace
coastal,
alluvial
flat, jointing rock,
lifting
of
Quaternary coral
reefs
and
earthquake;
Paleobathymetry, shows
coastal basement
condition exposed
by tectonic uplift
about 5.5 to 6
meters above sea
level for ± 5,500
years ago (BP);
The
coastal
vulnerability such
as
uplift
and
decreasing depth
the
Parepare
harbor also benthic
organism,
the
abrasion activity
more
intensive,
rock fracture and
high weathering,
unconsolidated
sediment,
vulnerable
to
abrasion
and
bearing capacity,
analysis of Landsat
7 ETM+ images
shows that erosion
and sedimentation
interaction
intensively work.

Tectonics and Paleo-bathymetry

2. Recommendations
Further research is
needed to support an
integrated management
of the coast.

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