Analysis of Pumice Thickness Layers As a Result of Rinjani Volcano Eruption in Lombok Island Based on Resistivity Data - repository civitas UGM

  

Preface

rd

  All praises are due to Allah, God Almighty, Who made this annual event of successful. The “3

Annual Basic Science International Conference (BaSIC-2013)” is an annual scientific event organized

by the Faculty of Mathematics and Natural Sciences, Brawijaya University. As a basic science conference,

it covered a wide range of topics on basic science: physics, biology, chemistry, mathematics and statistics.

  

In 2013, the conference took a theme of “Basic Science Advances in Energy, Health and Environment”

as those three aspects of life are hot issues.

  The conference in 2013 was the continuation of the preceding conferences initiated in 2011 as the

International Conference on Basic Science (ICBS), where it was a transformation from the similar

national events the faculty had organized since 2004. What also changed in year 2013 was the use of the

  

ISSN for the conference proceedings book, instead of an ISBN used in previous proceedings books. The

change was based on the fact that BaSIC is an annual event, and, therefore, the use of ISSN is more

appropriate. The proceedings book was also divided into four books: Physics, Biology, Chemistry and

Mathematics, each with a different ISSN. The proceedings were also published in electronic forms that can

be accessed from BaSIC website. I am glad that for the first time both types of publication can be realized.

  This event is aimed to promote scientific research activities by Indonesian scientists, especially

those of Brawijaya University, in a hope that they may interact and build up networks and collaborations

with fellow overseas counterparts who participated in the conference. This is in line with university vision

as a World Class Entrepreneurial University.

  I am grateful to all the members of the program committee who contributed for the success in

framing the program. I also thank all the delegates who contributed to the success of this conference by

accepting our invitation and submitting articles for presentation in the scientific program. I am also

indebted to PT Semen Gresik and PT PLN (Persero) for their support in sponsoring this event.

  I wish for all of us a grand success in our scientific life. And I do hope that the coming conferences will pick up similar success, and even better.

  Malang, April 2013 Johan Noor, Ph.D.

  Conference Chairperson

  

Foreword by the Rector of Brawijaya University

First of all I would like to congratulate the Organizing Committee for the success in organizing this

amazing event. I believe all dedicated time and efforts will contribute to the advancement of our beloved

university.

  I would like to welcome all participants, domestic and overseas, especially the distinguished invited

speakers, to Malang, to the conference. An international conference is a good means to establish and build

relationships and collaborations among participants. So, I hope this conference will facilitate all of you, the

academicians and scientists, to setup a network of mutual and beneficial collaboration. As a university with

a vision to be “A World Class Entrepreneurial University”, Brawijaya University will support all efforts to

realize that dream.

  Finally, I do hope that the conference will run smoothly and nicely and is not the last one. I would like to thank all parties who have lent their hands in making this conference happened.

  Malang, April 2013 Prof. Dr. Yogi Sugito Rector, Brawijaya University

  

Table of Contents

Preface .............................................................................................................................................................. i

Foreword by the Rector of Brawijaya University ........................................................................................... ii

Table of Contents ........................................................................................................................................... iii

Program Committee ....................................................................................................................................... iv

Scientific Program......................................................................................................................................... vii

Scientific Papers

  Invited Papers Cluster Dynamics by Ultra-Fast Shape Recognition Technique.................................................... I01 Nanotechnology Development Strategy for Supporting National Industry in Indonesia .............. I02 Role of Atomic Scale Computational Research in the Nanoscale Materials ................................. I03 Paeonilorin(PF) Strongly Effects Immuno System........................................................................ I04 Investigating Chlamydia trachomatis using mathematical and computational.............................. I05 Recent Trends in Liquid Chromatography for Bioanalysis ........................................................... I06 Submitted Papers Potential of desiccant cooling system performance in hot and humid climate country................ P03 The Orientation of Levels Thermal Comfort on Space (Case studied: Lauser International Building In The Ground Floor) .................................................................................................................... P05 Application of Induced Polarization to Estimate Saprolite and Limonite Deposits Case Study Kolo Bawah Area, Morowali Regency, Central Sulawesi..................................................................... P07 Simulation Design Of Earthquake On Fault Zone Using Stochastic Model (A Brief Review).... P09 A New Concept Water Saturation Estimation Based on Vertical Seismic Profiling Data ........... P10 Analysis of Pumice Thickness Layers As a Result of Rinjani Volcano Eruption in Lombok Island Based on Resistivity Data ............................................................................................................. P12

  

Investigation of Subsurface Structure With Integrated Geophysical Methods in Sedau, Lombok

Barat to Determined a Landslide Risk .......................................................................................... P13

Instrument Corrections for Broadband and Short-period Seimometers (Case Study: Japan's

Earthquake September 5th 2004) .................................................................................................. P14

Iron rock positioning determination, using the geomagnetic method, in the Mount Lawang, Aceh,

Indonesia ....................................................................................................................................... P15

Shoreline Changes and Seismic Vulnerability Index in The Earthquake Prone Areas (The Case of

Coastal North Bengkulu, Bengkulu Province-Indonesia)............................................................. P16

Array Technique Application to Determine Direction of Rupture of Tohoku's Earthquake, March

11th 2011....................................................................................................................................... P17

Installing Surface Microseismic Monitoring in Mt. Lamongan Geothermal Area (MLGA), East

Java, Indonesia .............................................................................................................................. P18

Magnetic Survey within Penantian Geothermal Area in Pasema Air Keruh, South Sumatra ...... P20

Application of Biot -Gassman Substitution methodin Generating Synthetic of S-Wave Sonic Log

for Simultaneous AVO Inversion ................................................................................................. P26

Detection of low velocity zone using receiver function analysis from CJ1 station ...................... P27

Analysis of The 3D Geothermal Reservoir Model from Anomaly Magnetic Data Using Mag3d

(Case Study: Rajabasa Geothermal field, Lampung Province, Indonesia) ................................... P28

Development of Information Systems to Semeru Volcano Activity using SMS : In Study ........ P29

Prediction Pattern Around Ground Water Depth TPA Supit Urang (Landfill) Using Geoelectric

Resistivity soundings Method ....................................................................................................... P30

CORRECTING THE PULL-UP EFFECT IN SEISMIC DATA USING PRE STACK DEPTH

MIGRATION METHOD ............................................................................................................. P32

Geomagnetic Data Interpretation of Mount Ungaran Geothermal Using Pseudogravity Transform

for Determining Heat Source Rocks ............................................................................................. P33

Analysis of seismic activity 1973-2012 in the volcanic arc system of West Nusa Tenggara (NTB)

to examine the Rinjani VolcanoActivity ...................................................................................... P35

Detection of seepage patterns direction in the Bajulmati Dam, Banyuwangi, Indonesia using

geoelectrical method, Schlumberger and dipole dipole configuration.......................................... P37

Comparison of Ammonia Yield using Nanocatalyst MnZnFeO and MnZnFeO at Ambient

Environment ................................................................................................................................. P38

  NITRIDING BEHAVIOR OF AISI 316 L in high density PLASMA NITRIDING .................. P39 The effect of deposited ZnPc islands in ZnPc/Polystyrene/Quartz Crystal oscillator stack for QCM based biosensor ............................................................................................................................. P40

  INFLUENCE OF THE WAVEFORM and DC OFFSET on THE ASYMMETRIC HYSTERESIS LOOP in Au/PZT/Pt/ Al2O3/ SiO2/Si THIN FILMS PREPARED by MOCVD METHOD ...... P41 Reactive Mixing In Stirred Tanks Under Different Kinds Of Perturbations (April 2013) ........... P42 Potential Benefits of Hypofractionation scheme to Improve Radiotherapeutic Ratio for lung cancer treatment (April 2012)................................................................................................................... P44 Comparison between general purpose crystal resonator and TCXO as reference frequency for frequency counter.......................................................................................................................... P45 Treatment Strategy for Dynamic Organs in Radiation Oncology................................................. P46 The Relation of Temperature to PM2.5 Production from Wood Burn ......................................... P49 Effect of Purification of Carbon From Coconut Shell pyrolisis With Acid Reaction Method in HCl

  1 M Solution.................................................................................................................................. P50 A Preliminary Application of Fuzzy Logic to Classify Volcanic Earthquakes and Tremors Recorded at Semeru Volcano, East Java, Indonesia ..................................................................... P51 Development of Instrumentation System for Heavy-Load Measurement Based on Piezoelectric Sensor............................................................................................................................................ P52

Acknowledgement....................................................................................................................................... Ack

  Program Committee Patrons Rector, Universitas Brawijaya Dean, Faculty of Mathematics and Natural Sciences, Universitas Brawijaya Advisory Boards Associate Deans 1, 2 and 3, Faculty of Mathematics and Natural Sciences, Universitas Brawijaya Chairperson Johan A.E. Noor, Ph.D. Deputy-Chair Dr. Suharjono Secretary Agus Naba, Ph.D. Treasurers Mrs. Sri Purworini Mrs. Rustika Adiningrum Mr. Surakhman Secretariat & Registration Dr. Masruroh dr. Kusharto Mr. Sugeng Rianto Mr. Gancang Saroja Conference Web Agus Naba, Ph.D. Publication & Proceedings Arinto Y.P. Wardoyo, Ph.D.

  Mr. Wasis Public Relations & Sponsorship Chomsin S. Widodo, Ph.D.

  Mr. Moch. Djamil Mrs. Firdy Yuana Venue Mr. Ahmad Hidayat Dr. Ahmad Nadhir Mr. Sunariyadi Mr. Purnomo Mr. Karyadi Eka Putra Accommodation & Hospitality Ms. Siti J. Iswarin

  Mrs. Nur Azizah Mr. Robi A. Indrajit Mrs. Trivira Meirany Master of Ceremony Himafis Transportation, Excursion & Social Events Djoko Santjojo, Ph.D.

  Dr. Sukir Maryanto Mr. Wahyudi Mrs. Arnawati Workshop, Poster & Scientific Exhibitions Hari Arief Dharmawan, Ph.D.

  Mr. Pudji Santoso Mr. Sahri Mr. Murti Adi Widodo Documentation Mauludi A. Pamungkas, Ph.D.

  Mr. Susilo Purwanto General Supports Himafis Scientific Program Dr. rer.nat. M. Nurhuda Dr. Sunaryo Mr. Agus Prasmono Local Scientific Committees (Reviewers & Editors) Physics Dr. rer.nat. Abdurrouf Adi Susilo, Ph.D. Mr. Unggul P. Juswono Dr.-Ing. Setyawan P. Sakti Biology Dr. Moch. Sasmito Djati Dr. Muhaimin Rifai Dr. Catur Retnaningdyah Chemistry Dr. Masruri Dr. Ahmad Sabarudin Dr. Lukman Hakim Mathematics Dr. Agus Suryanto Dr. Wuryansari M.K. Dr. Rahma Fitriani Dr. Solimun

  International Scientific Committee and Editors A/Prof. Lilibeth dlC. Coo, University of the Philippines, the Philippines Prof. Dr. Gereon Elbers, FH Aachen, Germany Prof. S.K. Lai, National Central University, Taiwan Prof. Kwang-Ryeol Lee, Korean Institute of Science and Technology, Korea A/Prof. Dann Mallet, Queensland University of Technology, Australia Prof. Lidia Morawska, Queensland University of Technology, Australia Prof.Dr. Petr Solich, Charles University, Czech Republic Dr. Michitaka Suzuki, Nagoya University, Japan Prof. Hideo Tsuboi, Nagoya University, Japan Prof. Jia-Lin Wang, National Central University, Taiwan

  Abstract — Pumice deposits as a result of eruption of Rinjani volcano in Lombok Island, where it spreads and the thickness of the layers are not clear yet (hypothetically only). One of powerful method is used to determine the thickness of the pumice layer by using resistivity method. The purpose of this research is to analyze the thickness of the pumice layer by the resistivity data. The result indicate that the fumice was found in all around of Lombok island (in East, North, Central, West, and South Lombok, respectively). The thickness pumice layers have a variation between 1.2 - 50 m, and its resistivity values ranging between 15- 441 Ωm which is situated in 2 to 5 layers of each locations. The variation of resistivity values and the number of layers depend on location distance, both horizontal and vertical direction from the center volcano eruption.

  Morphological units of the low and undulating ridge downslope complex occupies around Rinjani suchas Sambelia, Pusuk Mountains, Pemenang and west Sekotong, west Praya to Pujut of west Lombok characterized by slope angle less than 30 degrees. The river flow pattern is radial, dendritic and parallel, with the basic form of lava rock, fallout of firoclastic, and alluvium with forest vegetation. Its valley form U to V reflect the highly erosion. The rock formations compose the flat areas up to Coast, as follows [3]: i) Lokopiko Formation, the upper Pleistocene to Quaternary

  The main of pumice deposition scattered around Rinjani volcano, mainly trending NW-SE and in the South of the volcano. However, thick and broad knowledge of the distribution is still very low (hypothetically) [1]. Knowledge of deployment, structure and the thick layer of pumice is important, in addition to the availability of its potential, as well as an indicator of the history of big volcanic eruption such Rinjani. The purpose of this study was to analyze the thickness of the layer of pumice in Lombok Island based on the resistivity data.

  I. INTRODUCTION Lombok island geomorphology is dominated by mountains units in the North, while the South dominates by hills and in the Central is composed by plateaux. In general, the morphology of the Lombok island is composed by volcanic rocks and sedimentary rocks. Volcanic deposits consist of pebbles, gravel, sand, conglomerate, pumice, silt, clay, breccia, tuff, tuffaceous sandstone, while the sedimentary rock consist of limestone, limestone, and breccia.

  Hiden, S.B. Kirbani, S. Wiwit, D.S. Hadmoko, and Sismato

  

Analysis of Pumice Thickness Layers As a Result of

Rinjani Volcano Eruption in Lombok Island Based on

Resistivity Data

  (Tomk) Tertiary Oligocene to Miocene, alluvium sediment (Qa), clay (Cl), gravel (Pa) compose the Gunungsari area, Ampenan, Mataram, Cakranegara, Narmada, Labuapi.

  ) of old volcanoes result the pumice (Pu). It occupies an area Pemenang to Senggigi, Suranadi, northern Pringgarata, Mantang, Kopang, Sukamulia, Korleko, and Pringgabaya. iii) Tertiary Oligocene to Miocene Kawangan Formation

  VL

  ), the lower Pleistocene to Quarternary Lokopiko Formation Q

  tb

  ) results old volcanic rocks, alluvium sediment (Qa), pumice (pu), andesite (An). They are occupy an area of Bayan, Anyar, Santong, Sukadana, East Sesaot and Gondang. ii) Kalibabak Formation (Q

  VL

  (Q

  ) and then Sembelia alluvia sediment (Qa), Gili Lawang and Gili Sulat.

  Keyword — Eruption, fumice, resitivity, volcano

  VB

  The rock composition of peak area of Mount Rinjani, north Bayan, Sesaot, east Sembalun and Sembelia. It composed by Quaternary to Late Holocene (Qhv(R)). Pemenang (Qhv(PN)) rock is the result of volcanic rocks and lake sediment (Q

  Lombok island is an archipelago of the Lesser Sunda or Nusa Tenggara which are separated by the Lombok Strait from Bali to the west and the Alas Strait to the east of Sumbawa. It is roughly spherical with a kind of "tail" on the southwest side whose length is about 70 km. It reaches 5,435 km² which is in the rankings of the 108 big island in the world.

  B. Geomorphological of Lombok Island

  ) [2]-[3]

  tb

  ) and Kalibabak Formation (Q

  vL

  ) such as andesite (An), quartz sand (Pk), pumice (Pu), gravel (Pa) and TRAS (Dv). These area are crossed by Koko Grenggengan and Koko Blimbing. In the southern Rinjani volcano is occupied by the Narmada, Suranadi, Pringgarata, Mantang, Kopang, Terara, Sikur, Masbagik and Aikmel. Where the country rocks are arranged by Pleistocene Lokopiko Formation (Q

  VL

A. Regional Geological Structure of Lombok Island

  The area of Sembelia, Belanting and Sembalun of East Lombok are a result of Quarter Holocene volcanic rock and sediment volcanic rock such andesite. In the eastern of this area are alluvium and coastal sediments (Qa), as well as in Sembalun. Pringgabaya region composed by Pleistocene Lokopiko Formation (Q

  Geological structures of Lombok island is consist of normal faults and shear faults generally trending in northwest- southeast. At the beginning of the Pliocene to Pleistocene volcanic activity of volcano Lombok groups compose some formations such as Kalipalung with Selayar Member, Kalibabak, and Lokopiko. Volcanic activites occured since the Pleistocene to Recent controlled by Rinjani, Pusuk and Nanggi volcanoes.

  (An) are located in Penujak, Sengkol, in the south of Mujur, Jerowaru, and Keruak.

  1

     

     

     

       

      

       

  

  4

  2

  1

       

  1

  1

  2 ² _{4 3 2 1} MN MN AB r r r r K 

  

  Where 

  a

  a value and spacing AB/2 as an input in the inversion process to obtain the actual value of resistivity, thickness and depth of subsurface rock layers.

  III. METHOD This research has been carried out respectively in East

  Lombok, North Lombok, Central Lombok, West Lombok and South Lombok, respectively. Resistivity measurements by using the Schlumberger configuration with a separation long of AB/2 maximum is 300 m, and MN/2 ranging up 0.5 to 25 m.

  The data collected from the data years of 1996 (PAT NTB) and the measured its own from the year 2010 until years 2012. Th Gsound resistivity meter is used. Field data measured by spation AB/2 and MN/2 are potential difference ( ΔV) and current (I). The Processing is conducted to obtain the physical parameters of the rock below the surface such as the actual value of resistivity, thickness and depth of the layer of pumice. Interpretation of the geological rock resistivity values are based on the local geology.

       

  (2)

  II. BASIC THEORY

  1. Subsurface consists of several layers bounded by fields and there is a horizontal boundary resistivity contrast between the border areas.

  A. Pumice

  Volcanic eruptions can produce pumice is Strombolian and Plinian. Plinian type eruption of Rinjani volcano produces pumice. Pumice-rich pyroclastic flows obtained from the ruins of an eruption column. Pumice flow is more energetic and mobile. This section has a lower density, but larger stores kinetic energy generated by the vertical thrust up to a few kilometers above the volcano peak. The farther pumice fall, the greater the kinetic energy and faster horizontally.

  Single type of Plinian eruption can raised up hundreds of pumice flow, especially radial flow down the valley that radiate out from the top of the volcano. Variations in individual streams, the length of a few kilometers to tens of kilometers. It is the little things (miniscule), when compared with the massive pumice flow generated by caldera collapse. Caldera generate frictionless flow into the valley, filling valleys and low mountains adjacent cover. This flow produces predominantly pumice pyroclastic flow sheet at ( http://www.geology.sdsu.edu/how_vocanoes_work/thumblin ks/eruttypes_page.html )[4].

  Pumice has characteristics: hollow, generally grayish white to yellowish, has a specific gravity ranging between 1 - 2,5 gram/cm

  3

  . An eruption of volcanic material, generally has acid composition, formed by the rapid cooling, thus causing the gases contained in the eruption of rock out and leave scars cavities in it. This pumice has a grain size ranging from 2 mm up to 50 cm or more. Pumice has characteristics: hollow, generally grayish white to yellowish, has a specific gravity ranging between 1 - 2,5 gram/cm3. An eruption of volcanic material, generally has acid composition, formed by the rapid cooling, thus causing the gases contained in the eruption of rock out and leave scars cavities in it. This pumice has a grain size ranging from 2 mm up to 50 cm or more.

  B. Resistivity Meter

  Resistivity method used in the estimating subsurface conditions by utilizing electrical current injection into the earth through two current electrodes. Then the potential difference that occurs is measured by using two potential electrodes. From the measurement results of current and potential difference can be determined variation in resistivity of each layer below the measuring point.

  There are some basic assumptions that can be used in geoelectric resistivity method, namely [5]:

  2. Each layer has a certain thickness, except for the bottom layer of infinite thickness.

    

  3. Each layer is considered homogeneous isotropic.

  4. There is no current source in addition to current injected over the surface of the earth.

  5. The electrical current is injected electric current.

  Each layer have different resistivity value. Soil resistivity depends on several geological parameters, such as the type of mineral and water content, porosity and degree of water saturation in the rock, and other fractures.

  Potential in a homogeneous isotropic medium is considered always energized. Relationship between the large electric field (E) that occurred with the current density (j) flowing in the medium, according to Ohm's Law [6]:

  j =  E (1)

   is the electrical conductivity of rock material When a current is injected into the earth, the potential difference observed on the surface. Then the resistivity value will obtained, it describe indirectly a layer of earth resistivity particular. However, this value is not the true resistivity values . Resistivity is a magnitude whose value depends on the electrode spacing. In the fact, the earthis consists of layers with different resistivity values, so the potential is measured as the effect of these layers. The difference resistivity are called apparent resistivity, ( 

  a

  ) as in the following equation[7]:

  I V K a

  IV. RESULTS The resistivity measurement is conducted as much as about 300 points of each sounding. It situated in the East Lombok such area: Sembelia, Pringgabaya, Selong, Kayangan Port. Then, in the North Lombok such area: Rempek, Panggung Barat, Lempenge and Gangga. In the Central Lombok such area: Terara Janapria, Mantang Batukliang, Narmada Pringgarata and Mujur. In the West Lombok such area: Senggigi, Malaka, Kebun Buncit Lembar, Jembatan Kembar Fig. 1. 2D geoelectric cross section respectively for Tracks I and II . Grebekan and Senggigi, while in the South Lombok is conducted in Kidang and Sekotong.

A. Analysis of Pumice in East Lombok District

  Produced pumice from the eruption of Rinjani volcano estimated by 44,581,539 tons [1] and the most widely available in East Lombok, such in Ijo Balit District Labuan Haji. One of the research is conducted by our student using 2D resistivity method. Re-data processing and interpretation were conducted in the four trajectory (path length 150 m respectively). Where the research area is flat and a plantation.

  Fig. 2. Pumice stone outcrops, Ijobalit East Lombok

  2D resistivity cross-section (Fig. 1) with an average error 6.88% and a maximum depth of 12.4 meters and detected

  TABEL 1 resisitivitas values range between: 6.65 Ωm to 1264 Ωm. The

NTERPRETASION OF LITHOLOGY BASED ON RESISTIVITY DATA

  I data inversion results correlated to the geology and outcrop

  Line/ Resistivity( Depth(m) Thick type of

  (Fig. 2) the study area were observed directly in the field. Layer (m) lithology

  Ωm) 1/1 441-1264 0-6,4 6,4 Top soil

  Rock resistivity, thickness and depth of each trajectory can be

  ½ 154-441 6,5-9,5 3,0 fumice seen below. 1/3 31,8-154 9,5-12,4 clay -

  Cross-section of each trajectories in a row from the top (I,

  2/1 188-505 0-6,5 6,5 Top soil

  II, III, IV) interpreted consists of 3 layers, 150m path length

  2/2 70,1-188 6,5-11,5 5,25 Fumice

• 2/3 15,9-70,1 11,5-12,4 Clay and depth of 12.4 m below the surface, as in Table 1 below.

  3/1 198-771 0-3,75 0-3,75 Top soil

  In Table 1, it can be seen that the first layer (top soil),

  3/2 51,0-198 0-9,75 0-9,75 Fumice

  consists of dried tras so generally high resistivity values. Top

  3/3 6,65-51,0 3,75-12,4 2,65-8,65 Clay

  soil thickness averaged more than 6 meters except on the third 4/1 322-872 0-6,38 6,38 Top soil

  4/2 119-322 6,38-9,5 3,12 Fumice

  trajectories. The second layer is interpreted as a pumice stone

  4/3 26,6-11 9,5-12,4 - clay

  with resistivity values between 51- 441 Ωm. Thick layer of 3.0 to 9.75 m with kedamalan varied from 0 to 12.4 m measured

  For Belanting Sembelia, Pringgabaya and Selong areas, the from the local ground level. sounding data used to analyze the pumice. Cross-section of each trajectories in a row from the top (I,

  Based on the interpretation of the lithological composition of

  II, III, IV) interpreted consists of 3 layers, 150m path length the layer on top and spread vertically, respectively: Top soil in and depth of 12.4 m below the surface, as in Table 1 below. the form of thick clay 1,05 m, a second layer with a thick

  In Table 1, it can be seen that the first layer (top soil), pumice 2.54 m at a maximum depth of 3.59 m, and three consists of dried tras so generally high resistivity values. Top layers under the under te second layer is tuff and clay are soil thickness averaged more than 6 meters except on the third interspersed. trajectories. The second layer is interpreted as a pumice stone

  Stratigraphy of rock structures in the East Lombok based with resistivity values between 51- 441 Ωm. Thick layer of 3.0 on resistivity data of each: 1) Sembelia area, generally to 9.75 m with kedamalan varied from 0 to 12.4 m measured alternating between breccias, sand, clay, sandy tuff, and lava. from the local ground level.

  The number of layers one up to two, the average layer is on the third and fifth layers are usually flanked by a layer of sand or breccia or breccia and breccia. 2) In Belanting areas, it dominated by sand tuffaceous, 3) while in Geres and Sakra

  Fumice Selong layers alternating between sand and clay tuffaceous.

  The number of layers varies from 2 to 5 with an average thickness of between 3 and 50 m.

  B. Pumice Analysis in Central Lombok Area

  Results of analysis of pumice in the Central Lombok each: Janapria, Batukliang, Narmada and Sengkerang, constituent rocks generally alternating between tuff, sand, volcanic

  Fumic

  breccia and pumice. Pumice layer generally consists of 2 to 4

  e

  layers that occupy layer 2 to 5. Average thickness between 1.2 meters to 30 meters. Stratigraphy of this area is based on the data of each 2) The thickness of the layer of pumice depends on the vertical geoelectric Terara area, Janapria generally dominated by and horizontal distance from the center of the eruption, the tuffaceous clay. Pumice occasionally punctuated by tuffaceous more the presence of the layers is getting thicker and sand. Being in Mantang and Narmada are generally dominated farther away from the source of the eruption of pumice by tuffaceous sand and pumice tuff. layer thinner. Need further research why the value of resistivity and layer thickness varies with both horizontal and vertical distance from the center of the eruption, and

  C. Pumice Analysis in North Lombok Area the factors that influence it.

  Information pumice in North Lombok, pretty much however, the geoelectric data supporting this research still ACKNOWLEDGMENT very minimal. Data exist only in the region of Malaka

  The author would like to thank the NTB PAT team for their Pemenang, Rempek, Panggung Barat, Sambik and Lempenge cooperation and given the permission to utilize the data in this and Gangga. In Panggung Barat area 3 point, in Rempek 2 paper, we extend thanks also to all those who have contributed points, 4 points in Sambik and in Lempenge 3 with 2D to the writing of this paper is complete. trajectory while in the Gangga only 1 point. Pumice in this area based on geoelectric data, has an average thickness

  REFERENCES between 2 to 8 meters at a depth of 2 to 30 metres as measured

  [1] Eko Bambang Sutedjo, 2010, Potensi Bahan Galian Propinsi Nusa Tenggara Barat, Dinas Pertambangan Nusa Tenggara Barat,

  at the local surface. Stratigraphy of the area is composed by ntbtamben@gmail.com www.distamben.ntb.go.id . clay, fumice, tuffaceous sand, breccia and lava.

  [2] Darman,H. & Saidi, H., 2000, An outline of The Geology Og Indonesia, IAGI. [3] Hamilton,W,1979, Tectonics of the Indonesia Region, Geological survey

  D. Pumice Analysis in West Lombok Area Professional paper 1078, Washington

  Pumice were analyzed in the Kebun Buncit Lembar, [3] Suratno, N., 1994, Peta Geologi dan Potensi Bahan Galian Nusa Tenggara

  Barat, Skala 1:250.000, Kantor Wilayah Departemen Pertambangan dan

  generally mixed with clay and sand. Thick layer of pumice

  Energi NTB

  here an average of 2.7 to 4 meters and is 2 to 6 meters below

  [4] Global Volcanism Program — Department of Mineral Sciences — the local surface. Pumice is the second layer, from the surface.

  National Museum of Natural History — Smithsonian Institution atau

  Lithological constituent structure in this region of the upper ( http://www.volcano.si.edu/world/volcano.cfm )

  [5] Robinson, E.S.&Coruh, C.,1988, Basic Exploration Geophysics, John row are: top soil, pumice, sandstone, silty clay, and breccia.

  Wiley & Sons,New York. [6] W.R. Telford, R.E. Sheriff, L.P. Geldart, 1990, Applied Geophysics, Second Edition, Cambridge University Press.

  E. Pumice Analysis in South Lombok Area [7] Reynolds, 1997, An Indtroduction to Applied and Enviromental

  Pumice in South Lombok deer area, generally exposed at the

  Geophysics, Jhon Wiley and sons Third Avenue, New York, NY 10158- 0012, USA.

  surface with the thickness and depth of ± 3 meters. Resistivity varies from 60- 428 Ωm. The second and the third layer is sand and clay. This stratigraphy is thought to result from the dynamic sedimentation river and marine sediments. Thus pumice thought to have originated from the river or from the tidal waves of the sea.

  An interesting all a above analysis of pumice layer on top is that the pumice generally consists of somewhere multi-layered and these layer from the surface down to get heavier. It is very interesting for Paleovolcano. Pumice layers are repeated in a place indicates that the volcanoes produce pumice in this case has been repeatedly Rinjani volcano erupting with a massive eruption and produce pumice. This is consistent with having been released in the "history of Rinjani volcano eruption" by USGS [5]. The question that arises is: when, how often, how much, how VEI, What effect, is there any relation to the current climate eruption occurred? Will be our next study.

  V. CONCLUSION Based on the analysis of pumice layer thickness by using resistivity data can be concluded as follows :

  1) Pumice layer thickness varies, respectively: East Lombok between 3-50 m, in Central Lombok between 1.2 - 30 m, in North Lombok between 2-8 m, in West Lombok from 2.7 to 4 m and 1-3 m in South Lombok.