part 14 geological survey for masang-2 heppgeological mapping was conducted with a topographical map...

Part 14 Geological Survey for Masang-2 HEPP

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PROJECT FOR MASTER PLAN STUDY OF HYDROPOWER DEVELOPMENT IN INDONESIA

SUPPORTING REPORT (2), Part 14

GEOLOGICAL SURVEY FOR MASANG-2 HPP RPOJECT

Table of Contents

Page

1 INTRODUCTION ...................................................................................................................... 1-1 1.1 General ......................................................................................................................... 1-1 1.2 Purpose and Scope of the Survey ................................................................................... 1-1 1.3 Methodology of the Survey ........................................................................................... 1-2

1.3.1 Geological mapping ........................................................................................ 1-2 1.3.2 Core drilling .................................................................................................... 1-2 1.3.3 Standard penetration test ................................................................................ 1-3 1.3.4 Field Permeability test ................................................................................... 1-3 1.3.5 Sampling of soils and rocks ........................................................................... 1-3 1.3.6 Laboratory test for foundation rocks ............................................................... 1-4 1.3.7 Laboratory test for construction materials ..................................................... 1-4

1.4 Quantity of the Survey ................................................................................................... 1-4 2 REGIONAL GEOLOGY AND SEISMICITY ........................................................................ 2-1

2.1 General .......................................................................................................................... 2-1 2.2 Regional Geology ......................................................................................................... 2-1 2.3 Regional Tectonic Setting and Seismicity ..................................................................... 2-3

2.3.1 Regional tectonic setting ................................................................................. 2-3 2.3.2 Historical and instrumental earthquakes around the project area .................. 2-3

2.4 Estimation of Design Seismic Coefficient .................................................................... 2-6 2.4.1 Seismic design criteria .................................................................................... 2-6 2.4.2 Design seismic coefficient of existing similar hydropower projects ............. 2-6 2.4.3 Estimation of peak ground acceleration by probabilistic analysis .................. 2-8 2.4.4 Estimation by Indonesia Seismic Map (ISM) .............................................. 2-10 2.4.5 Recommended design seismic coefficient for the project ............................ 2-11

3 GEOLOGICAL SURVEY RESULTS ..................................................................................... 3-1 3.1 General ........................................................................................................................... 3-1 3.2 Site Reconnaissance and Geological Mapping .............................................................. 3-1

3.2.1 Surface geological characteristics ................................................................... 3-1 3.2.2 Slope instability ............................................................................................. 3-5

3.3 Seismic Refraction Survey ............................................................................................ 3-5 3.4 Boring Investigation ...................................................................................................... 3-6 3.5 Laboratory Tests for Construction Material .................................................................. 3-7

3.5.1 Sand ................................................................................................................ 3-7

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3.5.2 Rock block ..................................................................................................... 3-8

4 GEOLOGICAL AND GEOTECHNICAL CONSIDERATION OF THE PROJECT SITE ............................................................................................................................. 4-1

4.1 General ........................................................................................................................... 4-1 4.2 Intake Weir Site ............................................................................................................. 4-1

4.2.1 Weir site A....................................................................................................... 4-2 4.2.2 Weir site B ...................................................................................................... 4-3 4.2.3 Weir site C ...................................................................................................... 4-3

4.3 Intermediate Pond Dike Site ........................................................................................ 4-4 4.4 Connection and Headrace Tunnels (Plan B) .................................................................. 4-4 4.5 Surge Tank and Penstock Area ...................................................................................... 4-5 4.6 Powerhouse Site ............................................................................................................ 4-5

5 CONCLUSIONS AND RECOMMENDATIONS .................................................................... 5-1

5.1 Summary and Conclusions ............................................................................................. 5-1 5.2 Geological Hazards and Recommendations ................................................................... 5-2

5.2.1 Potential geological hazards ........................................................................... 5-2 5.2.2 Recommendations for design and construction of the project ....................... 5-2 5.2.3 Further geological and geotechnical Survey ................................................... 5-3

FIGURE

Figure 1.1 Location of geological survey ........................................................................................ 1-5 Figure 2.1 Regional geological map (Note: Symbols are the same as those in Table 2.1

above) ............................................................................................................................. 2-2 Figure 2.2 Location of earthquake epicenters within ±2 geographical degrees from the

Masang-2 weir site in the period since 1973 to 2010 (from USGS seismic database) ........................................................................................................................ 2-4

Figure 2.3 Recent and historical major earthquakes along the SFZ and Subduction Zone (modified from EERI Special Earthquake, May 2007) .................................................. 2-5

Figure 2.4 Location of existing hydropower projects in Sumatra ................................................... 2-7 Figure 2.5 Cumulative number of the earthquakes versus magnitude for the period of 100

years around the Masang2 project site ........................................................................... 2-9 Figure 2.6 Cumulative number of the earthquakes versus magnitude for the period of 200

years around the Masang2 project site ........................................................................... 2-9 Figure 3.1 Geological Map.............................................................................................................. 3-4 Figure 3.2 Outcrops of limestone in the riverbed (A) and close view (B) ...................................... 3-2 Figure 3.3 Interbedded slate (A) and sandstone (B) within limestone ............................................ 3-2 Figure 3.4 Outcrops of greenstone .................................................................................................. 3-2 Figure 3.5 Outcrops of fine-grained tuff (A) and tuff breccia (B) .................................................. 3-3 Figure 3.6 Distributions of alluvial deposits ................................................................................... 3-3 Figure 4.1 Geological Section of the Weir Axis Alternative A ....................................................... 4-7 Figure 4.2 Geological Section of the Weir Axis Alternative B ....................................................... 4-8 Figure 4.3 Geological Section of the Weir Axis Alternative C ....................................................... 4-9

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Figure 4.4 Geological Section of the Intermediate Pond Axis ...................................................... 4-10 Figure 4.5 Geological Section along the Connection and Headrace Tunnel Alignment

Alternative B ................................................................................................................ 4-11

TABLE

Table 1.1 Items and Methods of Laboratory Tests Performed for Foundation Rocks ..................... 1-4 Table 1.2 Items and Methods of Laboratory Tests Performed for Construction Materials ............. 1-4 Table 1.3 Quantity of Geological Survey for the Simonggo-2 Project ........................................... 1-4 Table 2.1 Regional stratigraphy of the project site .......................................................................... 2-2 Table 2.2 Summary of design seismic coefficients of the similar projects in Sumatra ................... 2-7 Table 2.3 Summary of the estimated peak ground accelerations .................................................. 2-10 Table 2.4 Zone and zone coefficient ............................................................................................. 2-10 Table 2.5 Foundation type and correction factor ........................................................................... 2-11 Table 2.6 Return period and basic earthquake acceleration .......................................................... 2-11 Table 2.7 Design seismic acceleration estimated by ISM ............................................................. 2-11 Table 2.8 Summary of obtained design seismic acceleration ........................................................ 2-11 Table 3.1 Geological classification of seismic units ....................................................................... 3-5 Table 3.2 Summary of Boring Investigation Results ...................................................................... 3-6 Table 3.3 Summary of permeability test results .............................................................................. 3-7 Table 3.4 Location of sand source sampling ................................................................................... 3-7 Table 3.5 Summary of laboratory tests for fine aggregate material ................................................ 3-8 Table 3.6 Location of potential rock quarry Sites ........................................................................... 3-8 Table 3.7 Summary of laboratory tests for coarse aggregate material ............................................ 3-8 Table 4.1 Estimated rock mass parameters at the weir site B ......................................................... 4-2 Table 4.2 Japanese rock classification and empirically estimated rock parameters ........................ 4-2 Table 4.3 Estimated rock mass parameters at the weir site C ......................................................... 4-3 Table 4.4 Estimated rock mass parameters at the intermediate pond dike site B ............................ 4-4 Table 4.5 Estimated rock mass parameters for the waterway route ................................................ 4-5 Table 5.1 Recommended quantity of boring investigation for feasibility study ............................. 5-4

APPENDIX

Appendix A List of Earthquakes around the Project Site Appendix B Interpreted Seismic Profiles Appendix C Detailed Geological Logs Appendix D Boring Core Photos Appendix E Rock Classification System

Project for Master Plans Study of Hydropower Development Volume IV, Geology In Indonesia Geological Survey for Masang-2 HPP

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CHAPTER 1 INTRODUCTION

1.1 GENERAL

Geological survey was carried out for the Pre-feasibility Study for Masang-2 Hydroelectric Power Project under the Project for the Master Plan Study of the Hydropower Development in Indonesia. The Masang-2 project is a ROR-type scheme and mainly includes intake weir, intermediate pond dike (regulating pondage), connection tunnel, headrace tunnel, surge tank, penstock, powerhouse, access road, etc.

This supporting report presents the results of the geological and geotechnical investigations and recommendations for the planned Masang-2 project scheme. The analyses, conclusions and recommendations provided in this report are based on the understanding of the project scheme and on the geological and geotechnical consideration and evaluation of the existing project site conditions at the time of the geological survey as well as on some engineering judgments.

In addition, the geological survey was done by PT. CONUUSA ENERGINDO, a subcontractor of the Project for the Master Plan Study of Hydropower Development in Indonesia.

1.2 PURPOSE AND SCOPE OF THE SURVEY

The purposes of the geological survey were to explore and evaluate the foundation conditions and slope stability along the proposed waterways and at the planned structure sites in the project, as shown briefly below:

a) To evaluate the geological and geotechnical suitability of the project sites for the proposed ROR-type hydropower projects;

b) To provide geotechnical data and parameters necessary for geotechnical analyses and design of the proposed projects at the prefeasibility study stage; and

c) To foresee and provide solution against geological hazards or problems that may arise due to subsurface conditions.

In addition, the survey was also undertaken to evaluate the suitability of geological materials including the required excavation materials as construction materials for the project.

The scope of the geological survey is enumerated below:

a) Review of previous investigation reports and selected published geologic maps and documents


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pertinent to the project site;

b) Seismic refraction survey;

c) Site reconnaissance and geological mapping;

d) Boring investigation consisting of core drilling, standard penetration test, field permeability test and rock core sampling;

d) Laboratory tests for rock foundations and construction materials;

f) Geotechnical analyses and evaluations of the data obtained; and

g) Recommendations on mitigation or solutions for the identified geotechnical problems and impact in relation to design and construction of the proposed project structures.

1.3 METHODOLOGY OF THE SURVEY

1.3.1 GEOLOGICAL MAPPING

Geological mapping was conducted with a topographical map of 1/10,000 scale to produce detailed maps. The geological mapping was carried out around the project areas and their surroundings, mainly covering intake weir site, intermediate pond dike site, connection and headrace tunnel routes, powerhouse site, known faults and some identified lineaments.

In addition to morphological features, distribution of lithological unit and major geological structures, the surface geological mapping was focused mainly on below:

- Type/distribution/color/condition/composition of surficial deposits;

- Type/color/weathering/alteration/jointing/hardness/mineral composition of rocks;

- Distribution/dip/strike/size/fracturing condition of geological structures (fault, fold, etc.);

- Distribution/condition/indication/size of slope instability; and

- Distribution/condition (location, flow amount, temperature, smell, etc.) of seepage and spring.

1.3.2 SEISMIC REFRACTION SURVEY

The seismic refraction survey was conducted along the proposed waterway and around weir site to determine the nature and thickness of the overburden materials and depths to bedrocks and groundwater table and to locate the distribution of weak zones (faults and shear zones).

The seismic refraction survey was carried out by using an OYO McSeis 170f type Seismic Instrument with 24 seismometers (geophones). Blasting materials (explosives) were used to generate seismic source in order to detect deeper subsurface layers. Geophone intervals along the survey lines were


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maintained at 10 meters to produce high resolution data on subsurface layers.

The shot was recorded and reviewed at the site. The recorded data were plotted on time-distance graphs, and then interpreted into profiles of seismic wave velocity layers. The deduced seismic wave velocity layers were shown in profiles, using the ground surface profile prepared by the profile survey.

In addition, the seismic wave velocity layers distinguished were geologically and geotechnically interpreted in correlation with the findings in surface geological mapping and boring investigation.

1.3.3 CORE DRILLING

Two sets of hydraulic driven rotary drilling machines (YSO-01 type) were used for the core drilling at the project site. These machines both had a drilling capacity of 100 m depth with 76 mm of borehole diameter through rocks. Diamond bit was used for drilling rock and metal bit for drilling unconsolidated deposits for the best core recovery.

The dry rotary drilling method was used for unconsolidated and loose deposits above the groundwater level. After reaching groundwater level, the washing rotary drilling method was applied. In addition, water level in borehole was measured and recorded every morning before commencement of the day's drilling work during the drilling.

1.3.4 STANDARD PENETRATION TEST

Standard penetration tests (SPT) were conducted at intervals of 2.0 meter at every borehole in order to obtain the resistance of unconsolidated deposits to the penetration of the split barrel sampler and to take the disturbed samples for the purposes of material identification and laboratory test.

The resistance of the unconsolidated deposits was estimated by the number of blows (the N value) with a standard hammer of 63.5 kg in weight to penetrate 30 cm. The test results were used to evaluate the ground conditions with respect to the bearing capacity and strength for foundation stability analysis and design.

1.3.5 FIELD PERMEABILITY TEST

The field permeability tests were conducted at 3.0 to 5.0 m vertical interval in descending order at the drilled boreholes in order to obtain the permeability of foundation ground. The tests were made mainly with falling head or constant head method for unconsolidated and with water pressure test (Lugeon test) in bedrocks. The test results were used to evaluate the permeability of foundation ground, thereby making a suggestion for the foundation treatment of the proposed structure sites


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1.3.6 LABORATORY TEST FOR FOUNDATION ROCKS

Representative rock samples selected from the drilled cores were tested to obtain the index and mechanical characteristics of the foundation rocks. These laboratory tests were in accordance with ASTM standard methods. Table 1.1 lists the tests conducted and ASTM methods used.

Table 1.1 Items and Methods of Laboratory Tests Performed for Foundation Rocks Test Item Standard or Method Sample No.

1. Water absorption and bulk specific gravity ASTM C 127 10 2. Unconfined compression test of rock core specimen ASTM D2938 10 3. Elastic modules and Poisson’s ratio ASTM D3148 10 4. Splitting tensile strength test ASTM D3967 10 5. Ultra-sonic wave velocity test ASTM D2845 10

1.3.7 LABORATORY TEST FOR CONSTRUCTION MATERIALS

Some representative sand-and-gravel aggregate samples were taken from riverbed deposits and rock block samples from rock outcrops. These samples were tested to evaluate the suitability of the selected potential construction material source areas in accordance with ASTM as shown in Table 1.2 below.

Table 1.2 Items and Methods of Laboratory Tests Performed for Construction Materials Test Item Standard or Method Sample No.

1. Sieve analysis of aggregates ASTM C 136 10 2. Specific gravity and water absorption (fine aggregate) ASTM C128 10 3. Specific gravity and water absorption (coarse aggregate) ASTM C127 10 4. Clay lumps and friable particles in aggregate ASTM C 142 10 5. Soundness tests by sodium sulfate (for coarse and fine) ASTM C 88 10 6. Abrasion test of coarse aggregate by Los Angeles machine ASTM C535 10 7. Chemical (alkali) reactivity test ASTM C289 10

1.4 QUANTITY OF THE SURVEY

The site work of the geological survey started in early October 2010 and ended in late January 2011. Figure 1.1 shows the locations of geological survey. Table 1.3 summarizes the quantity of the survey.

Table 1.3 Quantity of Geological Survey for the Simonggo-2 Project

Survey Item Unit Survey Quantity

Remarks Contracted Performed

1. Geological mapping km2 25.0 25.0 2. Seismic refraction survey m 5,000 6,920 3. Core drilling m 250 460 12 boreholes 4. Standard penetration test Nos. 30 55 5. Field permeability test Nos. 50 92 6. Rock core samples Nos. 20 10 7. Laboratory test for foundation rock Nos. 20 10 8. Laboratory test for construction material Nos. 10 10


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Figure 1.1 Location of Geological Surveys

Project for Master Plans Study of Hydropower Development Volume IV, Geology In Indonesia Geological Survey for Msang-2 HPP

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CHAPTER 2 REGIONAL GEOLOGY AND SEISMICITY

2.1 GENERAL

The Masang-2 project site is located approximately at 0°5’ to 0°10’ of the south latitude and 100°11’ to 100°15’ of the east longitude on the upper course of the Masang river about 30 km northwest of Bukit Tinggi city, about 100 km northwest of Padang city, the capital city of west Sumatra.

Geologically the project site is in the immediate proximity of the Sumatran Fault Zone (SFZ), also called Great Sumatra Fault System (GSF), one of the most seismically active zones in Indonesia, it is thus required to evaluate the regional geological background and seismic hazard at the project site and to design the project facilities to withstand the anticipated ground motions.

This chapter presents the pre-feasibility level regional geological and seismic hazard assessment for the Masang-2 project and provides the recommended design seismic coefficient for structural design of the project based on existing and published information as well as brief project site inspection. Some similar projects within Sumatra were reviewed to supplementarily determine design seismic parameter.

2.2 REGIONAL GEOLOGY

Physiographically the project site is located at the central Barisan system, which consists of a number of NW-SE trending block mountains. These block mountain ranges are highest on the southwestern side of the Barisan System, which they attain altitudes of over 2,000 m. They descend towards the east Sumatran lowlands. The Masang River originates from Mt. Marapi (El. 2,891.3m) and runs between these NW-SE trending block mountains. Around the project site the river flows to northwest subparallel to Great Sumatra Fault System and then toward southwest after the confluence with joins the Alahan Panjang River around the planned powerhouse site.

The regional stratigraphy of the project area is given in Table 2.1 and the regional geological map is shown in Figure 2.1. The regional stratigraphy of the project site begins with the Carboniferous to Permian. They consist of mainly the Carboniferous to Middle Permian shallow marine sedimentary rocks and the Permian volcanic rocks. In the Mesozoic, the sedimentation of shallow marine rocks was followed by uplifting, intrusion, metamorphism and faulting with the Cretaceous. These rocks and those of the Miocene intrusive rocks compose the bedrocks of the region. The Quaternary rocks, consisting mainly of pumiceous tuff and andesite from the volcanic activity of the Maninjau Volcano unconformably overlie extensively the older formations. The recent sediments, represented by


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alluvium, are of limited occurrence.

Table 2.1 Regional stratigraphy of the project site Age Symbol Formation Lithoogy

Quaternary

QTau Undifferentiated flows

Lahars, fanglomerate and other colluvial deposits

Qpt Pumiceous tuff and andesite

Pumiceous tuff: slightly consolidated, consisting of shards glass and white pumice, locally containing layers of sands and gravels of quartz, volcanic rock and limestone. Andesitic rocks association: consisting of undifferentiated flows, lahars, tuff, colluvial deposits, etc.

Cretaceous Kub Greenstone Greenstone (serpentinite) related to fault zone, sheared and fractured

Permian PI Limestone White, gray and reddish, cavernous, hard limestone, containing

intercalation of slate, phyllite.

Ps Metamorphic Rock

Consisting of phyllite, slate and mica greywacke, dark gray to blackish blue.

(Source: Geological Map of the Padang Quadrangle, Sumatra, 1:250,000)

Figure 2.1 Regional geological map (Note: Symbols are the same as those in Table 2.1 above)

The major geological structure is the Sumatran Fault Zone (SFZ), also called Great Sumatra Fault System (GSF), one of the most seismically active zones in Indonesia. The SFZ, generally parallel to the Sunda trench, results from the partitioning of oblique plate convergence into normal convergence at the trench and represents right-lateral strike-slip faulting. The SFZ of totally 1,900 km long is subdivided into 19 major segments. The major segment of the SFZ in the proximity of the project site is the Sianok segment (0.7oS to 0.1oN). The segment, approximately 90 km long, runs from the northeast shore of Lake Singkarak along the southwest flank of the volcano Marapi around the project


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site. In addition, volcanic activities are dominant in the region.

Several local NE-SW and NW-SE fault systems are also distributed in the general area of the project. The NW-SE fault systems, which are parallel to the SFZ, may be subsidiary to the SFZ.

2.3 REGIONAL TECTONIC SETTING AND SEISMICITY

2.3.1 REGIONAL TECTONIC SETTING

Sumatra Island is the northwest-oriented physiographic expression, situated at the boundary between the Eurasian and Indian Plates. The subduction zone around the Eurasian and Indian plates, called the Sunda Trench is formed due to the northeastward movement of the Indian plate relative to the Eurasian plate. This results in oblique convergence at the Sunda Trench. The SFZ, which is generally parallel to the trench, results from the partitioning of oblique plate convergence into normal convergence at the trench and represents right-lateral strike-slip faulting. Most deformations in Sumatra are concentrated between the Sunda Trench and the SFZ.

The SFZ, totally 1,900 km long, traverses the hanging wall block of the Sunda subduction zone, roughly coincident with the active Sumatra volcanic arc. The SFZ is a major transcurrent fault accommodating most of the dextral components of the Sumatran oblique convergence.

According to Sieh and Natawidjaja (2000), the SFZ is highly segmented and is divided into 19 major segments on the basis of its geomorphic and topographical expressions. These fault segments generally range in length from 35 km to 220 km. The major segment of the SFZ in the proximity of the project site is the Sianok segment (0.7oS to 0.1oN). The segment, approximately 90 km long, runs from the northeast shore of Lake Singkarak along the southwest flank of the volcano Marapi. Stream channels flowing off Marapi display clear dextral offsets that range from 120 to 600 m. In addition, the trunk channel of the Sianok River is incised into the 60,000-year old Maninjou Tuff and display offsets of about 700 m, thereby estimating a dextral slip rate of about 11 mm/yr at the segment (D. Natawidjaja and K. Sieh, 2000).

2.3.2 HISTORICAL AND INSTRUMENTAL EARTHQUAKES AROUND THE PROJECT SITE

The project site lies within a region of high seismicity. Appendix A shows the list of earthquakes recorded by seismic instruments for events greater than magnitude 5 from 1973 to 2010 through USGS National Earthquake Information Center. Figure 2.2 shows the distribution of these earthquake epicenters.

Earthquakes are distributed mostly between the subduction zone and the FSZ and especially concentrated along the subduction zone and the FSZ. In addition, the earthquakes around the FSZ


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generally have deep focal depths – represented by blue and green dots in Figure 2.2, whereas the earthquakes around the subduction zone shows shallow focal depths – represented by yellow and brown dots in Figure 2.2.

Figure 2.2 Location of earthquake epicenters within ±2 geographical degrees from the Masang-2 weir site in the period since 1973 to 2010 (from USGS seismic database)

Historical earthquakes have caused surface ruptures along the SFZ. On average, major earthquakes occur once or twice every decade along the SFZ. Figure 2.3 gives historical major earthquakes along the SFZ and the subduction zone. The smaller ellipsoid shapes in Figure 2.3 indicate some surface rupture on the some segment of the SFZ, while the larger ellipsoid shapes along the subduction zone in Figure 2.3 indicate recent and historical megathrust events associated with the subduction zone and the SFZ. The seismic sources are dominated by the subduction zone and the strike-slip-type SFZ. The subduction zone and the SFZ are both active and capable to generate earthquakes up to Mw=8.7 (1797) and Ms=6.6 (1926), respectively.

Notable historical earthquakes along the Sianok segment in the vicinity of the project site include:

- Along the Sianok segment of the SFZ, magnitude Ms = 7.0, 1822, strong shaking at the southwestern flank of the Marapi VOlcano.

Masang2 weir site


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- Along the Sianok segment of the SFZ, magnitude Ms = 7.0, 1926, strong shaking at the southwestern flank of the Marapi Volcano.

- Western Sumatra Earthquakes – Most recent destructive earthquake occurred on Marh, 2007, two earthquakes, Mw = 6.4 (0.512oS, 100.524oE) and Mw = 6.3 (0.49oS, 100.52oE), separated by two hours. The earthquakes destroyed many structures on or near the SFZ, and the shaking was strongly felt in Padang. The epicenters were approximately 50 km from Padang. The surface rupture was found to be around the south and north of the Singkarak Lake and the fault offsets of this ruptures were up to 12 cm.

Figure 2.3 Recent and historical major earthquakes along the SFZ and Subduction Zone (modified from EERI Special Earthquake, May 2007)

Masang2 Project Site


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2.4 ESTIMATION OF DESIGN SEISMIC COEFFICIENT

2.4.1 SEISMIC DESIGN CRITERIA

All project facilities should be designed to withstand a level of earthquake-induced ground shaking. Two levels of design earthquake ground motion are generally considered and defined according to international guideline (ICOLD, 1989) as follows:

a) Maximum Credible Earthquake (MCE): The MCE is defined as the largest reasonably conceivable earthquake, which is considered likely to occur along a recognized fault or a seismological area. The MCE is the upper bond of the expected magnitude on a given seismic source, in general related to 5,000 years to 10,000 years return periods.

b) Operating Basis Earthquake (OBE): The OBE is the level of ground motion that all structures must be able to withstand and still remain functional. Any damage due to earthquake is repairable. The OBE ground motions are expected occur during the lifetime of the structure and generally correspond to 100 years to 500 years return periods.

The selection of seismic design criteria is generally based on the type of structures under consideration and the safety and environmental consequences of failure. The Masang-2 project mainly include some low risk structures (low impact), such as small and low weir dam, low dike pond and so on. Accordingly, the OBE is considered as design earthquake in the return period of 100 to 200 years, requiring that the project structures remain operable during and after the specific OBE.

2.4.2 REVIEW OF EXISTING SIMILAR HYDROPOWER PROJECTS

A number of hydropower projects, which are mainly ROR type, have been constructed within the Sumatra, mostly in the proximity of the SFZ. Table 2.2 summarizes design seismic coefficients of these projects, while Figure 2.4 gives the locations of these project as well as the Masang-2 projects. As seen from Table 2.2, the design seismic coefficient, k-values of these similar projects are mostly in the range from 0.12 to 0.15.


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Table 2.2 Summary of design seismic coefficients of the similar projects in Sumatra Project Name Design Facility Design Seismic

Coefficient Remarks

Tes-1 All structures 0.15 ROR. completed in 1991Besai All structures 0.15 LHD, completed in 2001Musi Intake dam 0.18 ROR, completed in 2006

Other structures 0.15 Underground structures 0.08

Singkarak Open structures 0.20 LHD, completed in 1998 Underground powerhouse 0.10

Merangin-2 Open structures 0.15 ROR, completed in Underground powerhouse 0.08

Remun All structures 0.12 ROR, completed in 2005Asnhan No.2 Tanga arch dam 0.24 ROR, completed in

Other open structures 0.12 Underground powerhouse 0.06

Asahan No. 3 Intake weir 0.15 ROR, under construction Open structures (more than 20m high) 0.12 Open structures (less than 20m high) 0.15 Underground structure 0.12

Peusangan All structures 0.15 ROR, under construction

Figure 2.4 Location of existing hydropower projects in Sumatra

Tes-1

Singkarak

Merangin

BesaiMusi

Asahan No.3

Asahan No.2

Lake Toba

Renun

Peusangan

Masang-2


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2.4.3 ESTIMATE OF PEAK GROUND ACCELERATION BY PROBABILISTIC ANALYSIS

The peak ground acceleration (PGA) in the return period of 100, 200 and 500 years was probabilistically evaluated on the basis of the instrumental earthquake records from 1973 to 2010. A total of 158 events of magnitude greater than 5 occurred in the area within a distance of about 200 km from the weir site.

In addition, these seismic events were recorded with different magnitudes, such as body wave magnitude mb, surface wave magnitude Ms, and moment magnitude Mw. The saturation levels are for mb=6.5, for ML=7.5 and for Ms=Mw=8.0 according to Kramer (2007).

The formulas used for the seismic hazard assessment are as follows.

1) Gutenberg-Richter Recurrence Law (magnitude-Recurrence Relationship)

Log(N) = a – bM (1)

Where N is the number of earthquakes per given time interval of magnitude greater than or equal to M. a and b are Gutenberg-Richter coefficients for that seismic events.

2) Distance Attenuation Relationship

a = 2000 e 0.8M / (d2 + h2 + 400) Cornell (1968) (2)

a = 5000 e 0.8M / (r + 40)2 Estava (1973) (3)

Where,

M: Magnitude of earthquake in Richter scale

d: Distance from epicenter to the project site (or damsite) in km

h: Depth of focus in km

r: Distance from focus to the project site (or damsite) in km

a: Peak ground acceleration in gal or cm/sec2

e: The exponential constant

Around the project area, the cumulative number of earthquakes for the period of 100 years and of 200 years is shown in Figures 2.5 and 2.6, respectively. Accordingly, the peak horizontal ground acceleration (a) at the damsite for each earthquake was estimated by the formulas of Cornell and Estava for comparison. In the course of the preliminary seismic hazard assessment, the seismic sources within 200-km radius around the weir site were assumed to be a seismic zone. The estimated peak ground accelerations are summarized in Table 2.3 below.


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Figure 2.5 Cumulative number of the earthquakes versus magnitude for the period of 100 years around the Masang2 project site

Figure 2.6 Cumulative number of the earthquakes versus magnitude for the period of 200 years around the Masang2 project site

Relationship between Accumulated Frequency and Earthquake Magnitudefor 100 years around the Masang2 Project Site

1

10

100

1000

5 6 7 8

Earthquake Magnidude (M) Log(Nc)=6.6745 - 0.7539 (M)

Acc

umul

ated

Fre

quen

cy (N

c)

Relationship between Accumulated Frequency and Earthquake Magnitudefor 200 years around the Masang2 Project Site

1

10

100

1000

10000

5 6 7 8

Earthquake Magnidude (M) Log(Nc)=6.9755 - 0.7539 (M)

Acc

umul

ated

Fre

quen

cy (N

c)


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Table 2.3 Summary of the estimated peak ground accelerations Perk Horizontal Ground Acceleration (g)

Return period 100 years Return period 200 years Return period 500 years Cornell Formula 0.10 0.14 0.21 Estava Formula 0.18 0.25 0.38

Accordingly, the probable peak ground acceleration, which was estimated with widely used Cornell Formula at the weir site, was in a range of 0.10g to 0.14g for the return period of 100 and 200 years.

2.4.4 ESTIMATION OF DESIGN SEISMIC COEFFICIENT BY INDONESIA SEISMIC MAP (ISM)

The design seismic coefficient for the hydropower project can be generally estimated by local seismic code, the “PETA ZONA GEMPA INDONESIA, 2005” - Indonesian Earthquake Zone Maps published by Water Resource Development and Research Center in 2005, as follows:

vaZa cd ××= and gaRk dh /×= (4)

Where, ad: Design seismic acceleration on the ground surface (gal)

ac: Basic seismic acceleration (gal)

Z: Zone correction coefficient

v: Correction factor for type of foundation ground

kh: Design horizontal seismic coefficient

R: conversion factor

According to the ISM, the Msang-2 project site is located in Zone E, the zone correction coefficient, Z, was thus taken to be 1.3 (intermediate value) according to Table 2.4. The correction factor, v was given to be 0.80 for weir site for rock foundation and 1.10 for other structures for the soil foundation (Table 2.5). In addition, the conversion factor, R is generally in the range of 0.40 to 0.60 empirically and was intermediately set to be 0.50.

The design seismic coefficients (kh) for the return periods of 100 and 200 estimated by the above-mentioned formula are given in Table 2.7.

Table 2.4 Zone and zone coefficient Zone Zone Correction Coefficient, Z

A 0.0 – 0.3 B 0.3 – 0.6 C 0.6 – 0.9 D 0.9 – 1.2 E 1.2 – 1.4 F 1.4 – 1.6


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Table 2.5 Foundation type and correction factor

Foundation type Dominant Period Ts (sec)

Correction v

Rock Ts < 0.25 0.80 Diluvium 0.25 < Ts < 0.50 1.00 Alluvium 0.50 < Ts < 0.75 1.10 Soft Alluvium Ts > 0.75 1.20

Table 2.6 Return period and basic earthquake acceleration Return Period

T (Year) Basic seismic acceleration

ac (g) 10 0.127 20 0.155 50 0.196

100 0.227 200 0.255 500 0.289

1,000 0.313 5,000 0.364

10,000 0.385

Table 2.7 Design seismic acceleration estimated by ISM

Return Period (year)

Design seismic coefficient (g) Other structures (soil foundation)

Weir site (rock foundation)

100 0.16 0.12 200 0.18 0.13

2.4.5 RECOMMENDED DESIGN SEISMIC COEFFICIENT FOR THE PROJECT

These design seismic coefficients obtained above are summarized in Table 2.8. As seen from Table 2.8, the design seismic coefficients obtained by probabilistic method are consistent with that by Indonesia seismic map. They both are also parallel to those of existing similar projects within Sumatra. In addition, the Masang-2 project is located within highly seismically active zone, especially close to the active fault – the Sianok segment of the SFZ with an average slip rate of approximately 11 mm/year.

Table 2.8 Summary of obtained design seismic acceleration Approach Design seismic coefficient Remarks

1. Existing similar projects 0.12 – 0.15 2. Probabilistic method 0.10 – 0.14 Cornell formula

3. Indonesia seismic map 0.12 – 0.13 Rock foundation 0.16 – 0.18 Strongly weathered tuff

foundation

Accordingly, the design seismic coefficient for the prefeasibility study of the Masang-2 project is recommended conservatively to be 0.15 for design of the weir and intermediate pond dike.


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CHAPTER 3 GEOLOGICAL SURVEY RESULTS

3.1 GENERAL

The geological investigation conducted at the prefeasibility stage for the Masang-2 project included geological mapping, core drilling, seismic refraction survey, in-situ tests and laboratory tests for foundation rocks and construction materials. This chapter presents the geological survey results.

3.2 SITE RECONNAISSANCE AND GEOLOGICAL MAPPING

The surface geologic features through geological mapping are shown in Figure 3.1 and are summarized in the following section.

3.2.1 SURFACE GEOLOGICAL CHARACTERISTICS

Four geological units were identified and classified. They are in the order of geological time from old to young 1) Limestone with some interbedded slate and sandstone, 2) Greenstone and 3) Pumiceous tuff with some andesitic rock association.

(1) Limestone interbedded with slate and sandstone

The limestone belongs to the shallow marine sedimentary rocks and the bedrocks of the project site. The rock is exposed chiefly along the Masang River valley and at the southern part of the project site. The weir for Plan B, the intermediate pond dike and the powerhouse would be founded on the rocks.

The rock generally strikes N120E and dips 45 degrees toward northwest. The limestone at outcrops is generally gray to grayish white, highly to moderately fractured and highly jointed, and slightly weathered (Figure 3.2). The limestone was occasionally observed to be highly fractured or jointed especially associated with local faulting. The rock is occasionally intercalated with slate and sandstone (Figure 3.3).


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Figure 3.2 Outcrops of limestone in the riverbed (A) and close view (B)

Figure 3.3 Interbedded slate (A) and sandstone (B) within limestone

(2) Greenstone (serpentinite)

The greenstone is of limited occurrence, mainly in the southern part of the project site around Kototinggi and Lariang and occasionally along the Masang River valley. The rock is tectonic rock and its original rock is probably andesite. The greenstone at outcrops is generally green to greenish grey, soft to extremely weak, highly fractured and sheared (Figure 3.4).

Figure 3.4 Outcrops of greenstone

A B

A B

A B

B

Limestone

Slate

Sandstone


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(3) Pumiceous tuff

Pumiceous tuff with some andesitic rock association is extensively distributed over the hill slopes in the project site. The pumiceous tuff can be subdivided into two rock types, fine-grained tuff and tuff breccia (Figure 3.5). The fine-grained tuff overlies the tuff breccia.

The fine-grained tuff is generally gray brown to brown and slightly consolidated, and consists of silt to sand with some glass and pumice materials. On the other hand, the tuff breccia is brown or gray brown (weathered color) to gray (fresh color), semi-consolidated and includes lots of andesitic and basaltic fragments.

Figure 3.5 Outcrops of fine-grained tuff (A) and tuff breccia (B)

(4) Recent deposits

The recent deposits were observed in the project site. They locally overlie the tuffs and limestone. , especially on the lower slopes of the project area. These deposits consist mainly of valley-fill alluvium, hillslope colluviums and reworked volcanic deposits. The thickness of these deposits is variable, generally in the order of 1 to 10 m.

The alluvial materials contain a large quantity of subangular to rounded gravel and boulder of andesite and basalt (Figure 3.6).

Figure 3.6 Distributions of alluvial deposits

A B

A B


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Figure 3.1 Geological Map


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3.2.2 SLOPE INSTABILITY

From topographical interpretation and field reconnaissance no slope instability or potential landslides were identified around the planned project structures. However, some steep slopes may be prone to limited and localized surficial instability in the form of shallow collapse involving weathered tuff and colluvial deposits.

3.3 SEISMIC REFRACTION SURVEY

The seismic refraction survey was performed to evaluate the subsurface conditions of the project facilities; including depth to and strength of the bedrocks, depth to groundwater and subsurface stratigraphy. Because of no borehole information available, the basic geological units were identified based on the interpreted seismic velocity and the site-specific information through geological mapping.

The locations of the seismic survey lines are shown in Figure 1.1 before. The interpreted seismic profiles are given in Appendix B. The interpreted seismic data indicate that four velocity layers underlie the project site. The interpreted geological classification is summarized in Table 3.1 below.

Table 3.1 Geological classification of seismic units Seismic velocity (m/sec) Interpreted geological classification Layer thickness (m)Weir site B, ML-1 and ML-2

1. 300 – 450 Surficial deposits (talus, alluvial, etc.) 0.6 – 3.7 2. 820 – 1,400 Highly weathered/fractured limestone 0.6 – 14.8 3. 1,800 – 2,800 Moderately weathered/fractured limestone 10.0 – 90.0 4. >4,300 Slightly weathered/fractured limestone -

Weir site C, ML-3 and ML-4 1. 300 – 450 Surficial deposits (talus, alluvial, etc.) 0.2 – 2.5 2. 820 – 1,100 Highly weathered fine-grained tuff 1.9 – 21.8 3. 1,600 – 2,100 Moderately weathered tuff breccia 10.3 – 66.8 4. 2,200 – 3,600 Slightly weathered rocks -

Inlet area of waterway route (Plan B/C), ML-5 and ML-6 1. 360 – 500 Surficial deposits (talus, alluvial, etc.) 1.0 – 3.8 2. 880 – 1,500 Highly weathered fine-grained tuff 0.0 – 6.6 3. 1,700 – 2,200 Moderately weathered tuff breccia 15.0 – 36.0 4. 3,800 – 4,600 Slightly weathered rocks -

Intermediate pond dike site (Plan B/C), ML-7 to ML-11, L-5 and L-6 1. 300 – 500 Surficial deposits (talus, alluvial, etc.) 0.6 – 9.0 2. 700 – 1,100 Highly weathered/fractured limestone 1.0 – 11.9 3. 1,100 – 2,500 Moderate weathered/fractured limestone 3.6 – 53.0 4. 3,700 – 3,800 Slightly weathered/fractured limestone -

Surge tank and powerhouse (Plan A/B/C), ML-12 to ML-14 and L-3 to L-4 1. 300 – 500 Surficial deposits (talus, alluvial, etc.) 0.2 – 6.0 2. 700 – 1,500 Highly weathered fine-grained tuff 1.4 – 8.2 3. 1,700 – 2,500 Moderately weathered limestone/ tuff breccia 5.6 – 76.0 4. >4,600 Slightly weathered limestone -


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Connection tunnel (Plan B/C), L-1 and L-2 1. 400 – 500 Surficial deposits (talus, alluvial, etc.) 1.0 – 9.3 2. 1,000 – 1,200 Weathered fine-grained tuff 0.9 – 6.2 3. 1,700 – 2,700 Highly fractured limestone/weathered tuff breccia 3.6 – 73.4 4. >3,300 Slightly weathered limestone -

3.4 BOREING INVESTIGATUON

The boring investigation together with field permeability test was conducted to explore and evaluate the subsurface conditions of the project site. The results of boring investigation is summarized in Table 3.2, while more detailed geological logs are given in Appendix C and boring core photos shown in Appendix D.

All strata or geological units encountered during drilling are the Quaternary alluvial and colluvial deposits, the Quaternary tuff/tuff breccia and andesite, as well as the Permian limestone with interbedded thin slate. The rock masses encountered were classified according to Japanese Rock Classification Standard, as shown in Appendix E. Because of mechanical breaking due to drilling machine the rock class from core observation was lower than that at outcrops.

Table 3.2 Summary of Boring Investigation Results Area Bore Location Geology Weathering/Fracturing Rock class

MW-1 Right bank 0-11.2m alluvial/colluvial 11.2- 50.0m tuff breccia

0-11.2m Completely 11.2-50.0m Highly

0-11.2m D 11.2-50.0m D/CL

Weir site A MW-2 Riverbed 0-4.8m alluvial/colluvial 4.8-20.0m tuff breccia


0-4.8m D 4.8-20.0m D/CL

MW-3 Left bank 0-9.8m alluvial/colluvial 9.8-40.0m tuff breccia


0-9.8m D 9.8-40.0m D/CL

Weir site B MW-4 Right bank 0-7.4m alluvial/colluvial

7.4-30.0m limestone

0-7.4m Completely 7.4-17.0m Completely 17.0-23.0m Moderately 23.0-30.0m Completely

0-7.4m D 7.4-17.0m D/CL 17.0-23.0m CM 23.0-30.0m D/CL

MW-5 Left bank 0-10.0m alluvial/colluvial 10.0-30.0m limestone


0-10.0m D 10.0-30.0m D/CL

Weir site C MW-6 Left bank 0-4.0m alluvial/colluvial 4.0-19.8m tuff 19.8-30.0m tuff breccia


0-4.0m D 4.0-30.0m D/CL

Intermediate pond site

MW-7 Right bank 0-4.0m alluvial/colluvial 4.0-30.0m limestone

0-4.0m Completely 4.0-7.8m Highly 7.8-30.0m Moderately

0-4.0m D 4.0-7.8m D/CL 7.8-30m CM/CH

MW-8 Riverbed 0-6.0m alluvial/colluvial 6.0-20.0m limestone

0-6.0m Completely 6.0-20.0m Moderately

0-6.0m D 6.0-20m CM/CH

MW-9 Left bank 0-3.0m alluvial/colluvial 3.0-40.0m slate

0-3.0m Completely 3.0-19.7m Moderately 19.7-40.0m Highly

0-3.0m D 3.0-19.7m CM/CH 19.7-40.0m D/CL

Headrace route MH-1 Plan A

0-10.0m alluvial/colluvial 10.0-19.7m tuff 19.7-69.0m tuff breccia 69.0-100.0m andesite

0-10.0m Completely 10.0-100.0m Moderately

0-10.0m D 10.0-100m CL/CH

Surge tank site MS-1 Plan A/B/C

0-0.5m alluvial/colluvial 0.5-28.5m tuff 28.5-41.0m tuff breccia 41.0-50.0m andesite


0-0.5m D 0.5-41.0m D/CL 41.0-50.0m CM/CH

Powerhouse site MP-1 Plan A/B/C 0-3.0m alluvial/colluvial

3.0-20.0m limestone


0-3.0m D 3.0-11.0m D/CL 11.0-20m CM/CH


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In addition, the results of field permeability tests are given in Table 3.3 together with underground water table measured at drilling. The permeability in the foundation rocks is generally in the range of 1.0×10-5cm/se to 1.0×10-3 cm/sec; thereby indicating moderately permeable foundation rocks.

Table 3.3 Summary of permeability test results Area Geology Permeability (cm/se) Groundwater (depth-m)

Weir site A Alluvial and colluvial deposits 3.63×10-4 - 4.94×10-3 MW-1: 3.0m Weathered tuff breccia 5.22×10-5 - 3.51×10-3 MW-3: 15.5m

Weir site B Alluvial and colluvial deposits 3.76×10-4 - 1.51×10-3 MW-4: 5.0m Fractured limestone 2.28×10-4 - 2.07×10-3 MW-5: 14.5m

Alluvial and colluvial deposits 5.00×10-3 MW-6: No water Weir site C Weathered tuff 2.99×10-3 - 1.37×10-2

Weathered tuff breccia 7.55×10-4 - 2.01×10-3 Intermediate

pond site Alluvial and colluvial deposits 1.00×10-4 - 1.56×10-3 MW-7: No water Fractured limestone 2.95×10-5 - 4.59×10-3 MW-9: No water

Headrace route

Alluvial and colluvial deposits 1.45×10-6 - 2.85×10-6 MH-1: No water Weathered tuff 1.53×10-5 - 3.73×10-5 Weathered tuff breccia 2.16×10-6 - 2.42×10-4 Weathered andesite 2.85×10-6 - 2.36×10-3

3.5 LABORATORY TESTS FOR CONSTRUCTION MATERIALS

The construction materials required for the construction of the project structures were fine and coarse aggregates, rock fill and impervious materials.

At the prefeasibility study stage the field reconnaissance (geological mapping) together with limited laboratory tests was carried out to examine the possible source, quantity and quality of construction materials.

3.5.1 SAND

Sand materials were needed for the fine aggregates of concrete, grout and mortar. Riverbed deposits around the Dukuh (SS-1 to SS-3), around the weir site (SS-4) and close to the powerhouse site (SS-5) were inspected. The Dukuh sites are in operation by local people. These sites are generally small in quantity.

Table 3.4 Location of sand source sampling Sample No. Coordinate Location

SS-1 00o 09.672’ 100o 14.874’ Dukuh 1, in operation SS-2 00o 10.22’ 100o 14.854’ Dukuh 2, in operation SS-3 00o 10.463’ 100o 14.857’ Dukuh 3, in operation SS-4 00o 08.804’ 100o 14.183’ Close to Weir Site for Plan A SS-5 Close to Powerhouse

The alluvial deposits are predominately coarse sand with some gravel. The content of fines is zero to 2 % only. Table 3.5 summarizes laboratory test results of the samples. Especially the absorption values of the alluvial sands are high and should be verified in a later survey stage if the materials are to be used in concrete.


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Table 3.5 Summary of laboratory tests for fine aggregate material Test Criterion SS-1 SS-2 SS-3 SS-4 SS-8

1. Specific gravity >2.5% 2.71 2.67 2.49 2.48 2.33 2. Absorption <3.0% 6.86 13.15 13.15 14.05 11.58 3. Soundness Na2SO4 12.0% 18.79 4.60 2.40 4.95 13.6 Mg2SO4 15.0% 4. Soft particle <1.0%

3.5.2 ROCK BLOCK

Several potential limestone quarries, RS-1 through RS-5 as shown in Table 3.6 around the project site were observed mainly as concreter coarse aggregate for the construction of project. Table 3.7 gives the results of laboratory tests. As seen from Table 3.7, the index properties are satisfactory for concrete aggregates except for compressive strength. The low strength values of the limestone quarries were presumably due to weathering because these samples were taken from surface outcrops. The strength property should be confirmed at next investigation stage.

Table 3.6 Location of potential rock quarry Sites Sample No. Coordinate Location

RS-1 00o 08.786’ 100o 14.053’ Lariang 1 RS-2 00o 09.148’ 100o 14.129’ Lariang 2 RS-3 00o 08.804’ 100o 14.183’ Weir Site Plan A RS-4 00o 08.381’ 100o 14.071’ Weir Site Plan B RS-5 00o 05.656’ 100o 11.112’ Powerhouse

Table 3.7 Summary of laboratory tests for coarse aggregate material

Test Criterion RS-1 RS-2 RS-3 RS-4 RS-5 1. Specific gravity >2.5% 2.76 2.71 2.58 2.71 2.71 2. Absorption <3.0% 1.00 0.89 2.89 0.59 0.32 3. Soundness Na2SO4 12.0% Mg2SO4 15.0% 4. Abrasion <40.0% 25.1 32.3 5. UCS >500kg/cm2 182 141 163 255 372

Notes: 1) UCS = Unconfined compressive strength, 2) 1 kgf/cm2 = 98.1kN/m2 (kPa).


4-1

CHAPTER 4 GEOLOGICAL AND GEOTECHNICAL CONDITION OF THE PROJECT SITE

4.1 GENERAL

At the prefeasibility study stage, three alternative layouts, Plan A, Plan B and Plan C were proposed for comparison assessment purposes. The general layouts of Plan A through Plan C were almost the same and included an intake weir, intermediate pond, connection and headrace tunnels, surge tank, penstock and a surface power station.

The following presents the preliminary geological conditions for the various project facilities including weir, intermediate pond dike, connection tunnel, headrace tunnel, surge tank, penstock and surface powerhouse.

4.2 INTAKE WEIR SITE

4.2.1 WEIR SITE A

Weir site A – The site is located approximately 300 m downstream of the confluence between the Cuntung river and the Sianok river. The Masang River at the weir site shows U-shaped valley with a riverbed width of about 30 m. The right and lift abutments are river terrace, which is used as agricultural lands.

The geological conditions at the site were investigated by three boreholes (MW-1 through MW-3). Figure 4.1 shows the geological section of the weir site A, which is based on the boring investigation and site reconnaissance. As shown in Figure 4.1, the overburden consisted mainly of alluvial deposits and their thickness was about 10 m at the abutments and 5 m in the riverbed. The underlying tuff and tuff breccia, especially its upper part was highly weathered into a poor quality of D class rock mass in Japanese Rock Classification Standard. The D class zone of the highly weathered tuff breccia is expected to be more 10 m in thickness. The rock classification system is given in Appendix E.

Accordingly the weir foundation at the site will require deep excavation up to over 10 to 20 m deep to remove the overlying loose deposits and highly weathered tuff breccia or a combination of pile foundation to improve the bearing capacity of foundation rocks.

In addition, because in-situ and laboratory test results are limited, the rock mass parameters, as shown in Table 4.1 for design were roughly determined from the conventionally adopted empirical table of


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design parameters (Table 4.2).

Table 4.1 Estimated rock mass parameters at the weir site B Item Riverbed, Left/Right abutment Remarks

Geological unit Slightly consolidated tuff breccia Rock classification (Japanese standard) D – CL class rocks Unit weight (ton/m3) 1.8 Unconfined compressive strength (MPa) 10 Internal friction anger (degree) 25° Cohesion (kPa) 500 Deformation Modulus (MPa) 500

Table 4.2 Japanese rock classification and empirically estimated rock parameters

Rock class

qu (kgf/cm2)

Es (kgf/cm2)

Ed (kgf/cm2)

c (kgf/cm2)

φ (degree)

V (km/sec)

A-B Over 800 Over 80,000 Over 50,000 Over 40 55 – 65 Over 3.7 CH 800 - 400 80,000 - 40,000 50,000 - 20,000 40 - 20 40 – 55 3.0 – 3.7 CM 400 - 200 40,000 - 15,000 20,000 - 5,000 20 - 10 30 – 40 1.5 – 3.0 D-CL Below 200 Below 15,000 Below 5,000 Below 10 15 - 30 Below 1.7

Source: Rock classification and its application, K. Yoshinaka, et al., Japanese Society of Civil Engineering, 1989.

Note: qu = Unconfined compressive strength, Es = Modulus of elasticity, Ed = Modulus of deformation, c = Cohesion, φ= Internal friction angle, V= Velocity of elastic wave, 1 kgf/cm2

= 100 kPa = 0.1 MPa.

4.2.2 WEIR SITE B

The weir site B for Plan B lies about 600 m downstream of the weir site A at the straight course of the river. The Masang River at the weir site shows wide V-shaped valley with a riverbed width of about 35 m.

Figure 4.2 shows the geological conditions of the weir site B. The thickness of the surficial deposits is in the order of 1 to 7 m. The underlying limestone is exposed in the riverbed and at the right abutment. From field reconnaissance and core observation the limestone is generally very hard and strong, moderately to highly fractured and can be classified into D to CM class rocks from Japanese Rock Classification Standard. Further, the interpreted seismic refraction indicate four velocity layers underlie the weir site B. The secondary layer with a seismic velocity of 820 to 1,400 m/sec is probably consistent with the highly weathered and fractured limestone. The layer has a thickness of 0.6 m to 15.0 m.

In addition, the permeability of the fractured limestone is in the range of 2.28×10-4cm/sec to 2.05×10-3 cm/sec and the limestone is thus considered to be moderately permeable rocks.

Accordingly the weir at the site B would be founded on the highly to moderately limestone. The foundation conditions at the weir are considered favorable with the weir structure founded in the limestone, however foundation treatment would be required to improve the permeability of the


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foundation rock.

Similarly, the rock mass parameters of the weir site B were empirically determined and given in Table 4.3.

Table 4.3 Estimated rock mass parameters at the weir site C Item Riverbed, Left/Right abutment Remarks

Geological unit Highly fractured limestone Rock classification (Japanese standard) D – CM class rocks Unit weight (ton/m3) 2.0 Unconfined compressive strength (MPa) 20 Internal friction anger (degree) 30° Cohesion (kPa) 1,000 Deformation Modulus (MPa) 2,000

4.2.3 WEIR SITE C

Weir site C – the site is located further 500 m downstream of the weir site B. The Masang River at the weir site shows wide V-shaped valley with a riverbed width of about 30 m.

The geology of the site, as shown in Figure 4.3, consists mainly of tuff, tuff breccia and limestone. The thickness of the highly weathered tuff and tuff breccia is over 30 m at the abutments. The underlying limestone crops out solely in the riverbed and is expected to be encountered at a depth of 35 to 40 m at the abutments. Because of poor quality of the weathered tuff and tuff breccia at the abutments, deep excavation or foundation treatment for the weir foundation would be required at the abutments.

4.3 INTERMEDIATE POND DIKE SITE

The intermediate pond site is located at the lower course of a small stream, a tributary of the Masang River close to Kototinggi village. The width of the streambed at the pond site is about 5 m. The left abutment is a thin ridge and the right abutment is a mountainous hillslope.

The geology of the intermediate pond site consists mainly of limestone and contains intercalated thin shale beds, as shown in Figure 4.4. Alluvial and colluvial deposits as well as tuff locally overlie the limestone mainly along the stream valley. The thickness of these superficial layers is in the range of 1 to 4 m at the abutments and in the range of 1 to 6 m in the streambed.

The limestone is generally hard, moderately fractured and jointed and can be classified as CM to CH class rock in Japanese Rock Classification Standard. On the other hand, the interbedded slate is moderately to highly fractured and sheared and can be classified as D to CM class rock.

The limestone and interbedded slate at the intermediate pond site has moderate to low permeability with a permeability of 2.95×10-5cm/se to 4.59×10-3 cm/sec. In addition, no groundwater was observed


4-4

during borehole drilling around the abutments, indicating that groundwater level around the abutments was very low.

Accordingly, the intermediate pond dike will be expected to be founded on the limestone, which is considered favorable in terms of bearing capacity. Leakage, however, would be likely to be encountered around the abutments and foundation rocks, especially from the right abutment of thin ridge.

In addition, according to the conventionally adopted empirical table of design parameters, as shown in Table 4.2 above, the rock mass parameters for the design of the proposed pond dike embankment were roughly determined and summarized in Table 4.4 below.

Table 4.4 Estimated rock mass parameters at the intermediate pond dike site B Item Riverbed and right abutment Left abutment

Geological unit Limestone Slate Rock classification (Japanese standard) CL to CM class rocks D to CL class rocks Unit weight (ton/m3) 2.0 1.8 Unconfined compressive strength (MPa) 20 10 Internal friction anger (degree) 35° 25° Cohesion (kPa) 1,000 500 Deformation Modulus (MPa) 2,000 500

4.4 CONNECTION AND HEADRACE TUNNELS (PLAN B)

In Plan B it is planned to construct 1,060 m long connection culvert, 1,630 m long connection tunnel and 4,550 m long headrace tunnel along the left side of the Masang River. The thickness of the overburden along the connection and headrace tunnel alignment is over 100m. No deep mountainous streams pass through the tunnel alignment.

The connection and headrace tunnels will be located mostly in limestone interbedded with slate and locally in tuff and tuff breccia. No detailed geological data are available from the rock masses along the most part of the tunnel alignment at surface and at the tunneling depth. The geological conditions considered are based mainly on surface geological mapping and boring information obtained in the vicinity of the tunnel alignments, as shown in Figure 4.4.

As seen from Figure 4.4, the foundation of the connection and headrace tunnels is expected to mostly be CM to CH class limestone with interbedded slate as well as tuff/tuff breccia, and locally D to CL class rocks over several tens meters relating to the interbedded slate and highly fractured limestone. Consequently the general rock mass conditions are considered favorable from the viewpoint of tunneling and no major geological problems are to be expected during heading of the tunnels.

The rock mass quality along the connection and headrace tunnels are expected to be classified in Japanese Standard in the following table.


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Rock type Rock class Length (m) Percentage (%) Remarks

Limestone/slate CM to CH 3,780 60% Total length: 6,180m D to CL 600 10%

Tuff/tuff breccia CM 1,800 30%

In addition, according to the conventionally adopted empirical table of design parameters, as shown in Table 4.2 above, the rock mass parameters for the design of the proposed tunnels were roughly determined and summarized in Table 4.5 below.

Table 4.5 Estimated rock mass parameters for the waterway route Item Headrace tunnel Connection tunnel

Geological unit Limestone interbedded with slate Tuff /tuff breccia Rock classification (Japanese standard) CM to CH D to CL CM Unit weight (ton/m3) 2.0 1.8 2.0 Unconfined compressive strength (MPa) 20 10 20 Internal friction anger (degree) 35° 25° 30° Cohesion (kPa) 2,000 500 1,500 Deformation Modulus (MPa) 3,000 500 1,500

4.5 SURGE TANK AND PENSTOCK AREA

The surge tank and penstock areas are located at the right side of the Masng River immediately downstream of the confluence between the Masang River and the Alahan Panjang River. Here slope stability and foundation conditions are the major topics of the geological investigations. The boring investigation of MS-1 revealed that the tuff and tuff breccia, about 40-m thick, is highly weathered with a rock quality of D to CL class in Japanese Rock Classification Standard and the underlying moderately weathered andesite is moderately weathered with a rock quality of CM to CH class. The surge tank will be expected to be founded on moderately weathered andesite.

Similarly, the penstock will be located on the hillslope underlain by highly weathered tuff and tuff breccia. The rocks are expected to be D to CL class rock mass in Japanese Rock Classification Standard. For the foundation of fix points of the penstock the foundation tuff might be very poor with a rock quality of D class. If such foundation condition would be encountered foundation treatment such as mortared rockbolts should be implemented to guarantee stable foundations.

4.6 POWERHOUS SITE

The powerhouse is planned at the right bank of the Masang River. From field reconnaissance and boring investigation (MP-1), the overburden is about 1 to 3 m thick and the underlying limestone is very hard, highly to moderately fractured with a rock quality of D to CH class in Japanese Rock Classification Standard. The limestone, although highly fractured, is considered to have a sufficient bearing capacity for foundation support of the planned powerhouse.


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Accordingly, because the foundation limestone is hard and strong and the overburden is thin, no major foundation problems will be expected. The limestone in the foundation area is suitable for the founding of the powerhouse.

Project for Master Plans Study of H

ydropower D

evelopment V

olume IV

, Geology

In Indonesia Geological Survey for M

asang-2 HPP

4-7

Figure 4.1 Geological Section of the Weir Axis Alternative A


ydropower D

evelopment V

olume IV

, Geology


asang-2 HPP

4-8

Figure 4.2 Geological Section of the Weir Axis Alternative B


ydropower D

evelopment V

olume IV

, Geology


asang-2 HPP

4-9

Figure 4.3 Geological Section of the Weir Axis Alternative C


ydropower D

evelopment V

olume IV

, Geology


asang-2 HPP

4-10

Figure 4.4 Geological Section of the Intermediate Pond Axis


4-11

Figure 4.5 Geological Section along the Connection and Headrace Tunnel Alignment Alternative B


5-1

CHAPTER 5 CONCLUSION AND RECOMMENDATIONS

5.1 SUMMARY AND CONCLUSIONS

The preliminary geological and geotechnical investigations conducted at the pre-feasibility study stage mainly included site reconnaissance, geological mapping, seismic refraction survey and laboratory tests of potential construction materials. On the basis of the preliminary geological and geotechnical investigations results the topographical and geological conditions of the project site were considered suitable for the development of the project.

The mainly investigation results are summarized as follows:

- The basement rocks of the project site are Permian limestone rocks with some thin intercalations of slate. The limestone rock is extensively covered by Quaternary tuff and tuff breccia from the volcanic activity of the Maninjau Volcano.

- In comparison with the weir sites A and C the weir site B is more suitable for founding of the weir construction because at the site the overburden is shallow and the foundation rock of limestone is hard and strong enough to support the planned weir foundation.

- The intermediate pond site was favorable in terms of bearing capacity; however the permeability and leakage of the foundation rocks should be considered especially leakage from the right abutment of thin ridge.

- The planned connection and headrace tunnels would be expected to be founded mostly on CM to CH class rock masses. No major geological problems are to be expected at tunneling.

- Limestone quarry sites around the project site appeared available in quality and quantity as potential construction material sources but the strength characteristics should be confirmed at next survey stage.

- No major slope instability are to be expected around the planned project structures, however, small and shallow soil collapses my be expected during the development the project, especially associated with the highly weathered tuff and tuff breccia.

- The project site is located in a region of high seismic activity close to the active Great Sumatra Fault, which is the major seismic source around the project site. The design seismic coefficient for the per-feasibility study of the Masang-2 project is recommended conservatively to be 0.15 for design of the weir and intermediate pond dike.


5-2

5.2 GEOLOGICAL HAZARD AND RECOMMENDATIONS

5.2.1 POTENTIAL GEOLOGICAL HAZARD

As stated before the geological and geotechnical conditions of the project site are suitable for the development of the project. However some potential geological hazards are expected to be encountered during the construction and subsequent operation of the project, as listed below:

- Leakage from the planned intermediate pond and its reservoir area.

(1) Leakage from the planned intermediate pond dike foundation and its reservoir area

The intermediate pond dike and its reservoir area are underlain by limestone. As mentioned above, the limestone is generally highly fractured and thus not watertight. In addition, although no sinkholes and settlements due the soluble property of limestone were found at the geological mapping, the limestone would be expected to highly fractured and jointed with numerous cavities and solution channels. The foundation limestone would be expected to have a complicated foundation and abutment problems – leakage of water below and around the foundation rock as well as from reservoir area.

Accordingly the expected geological hazard with the foundation limestone in the intermediate pond dike site is watertight and leakage of the foundation rocks and proper treatment method.

5.2.2 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION OF THE PROJECT

(1) Rock Mass Parameters

Because laboratory and in-situ test data for foundation rocks are limited, it is thus difficult to evaluate the rock mass conditions and mechanical properties of the foundation rocks. For the purpose of preliminary design of the project structures, it is recommended to use the roughly estimated rock mass parameters according to the conventionally adopted empirical table of design parameters, as given in Chapter 4, Geological and Geotechnical Conditions of the Project Site.

(2) Cut Slope Stability

The main cut slopes in the project site will be excavated at the following locations:

- In the area of intake weir abutments

- In the area of connection culvert route

- In the area of intermediate pond dike

- In the areas of the inlet and outlet of the connection tunnel

- In the areas of the inlet of the headrace tunnel


5-3

- In the area of the surge tank

- In the area of the powerhouse

These cut areas or slopes will be associated with the following geological units:

- Tuff and tuff breccia – Highly weathered, slight consolidated pumiceous tuff - soft rock

- Limestone – Highly to moderately jointed and fractured hard rock

- Interbedded slate – Highly fractured and sheared, soft rock

Because no geotechnical data are available for determining the strength properties of these rocks to give a reasonable factor of safety for the design of the cut slopes, empirical geometric standards for cut slopes are referred to determine the stable cut slopes.

The slope inclinations adopted for the various geological units are as follows:

- Tuff /tuff breccia: 1:0.8 (Vertical to Horizontal)

- Slate: 1:0.5 (Vertical to Horizontal)

- Limestone/Slate: 1:0.3 to 1:0.5 (Vertical to Horizontal)

In addition, for design of cut slopes, especially within the tuff B, measures are taken in order to drain the slopes and take care of the surface water. Diverting water away from the slope by introducing ditches is often recommendable.

5.2.3 FURTHER GEOLOGICAL AND GEOTECHNICAL SURVEYS

Further geological and geotechnical investigation works for next stage – Feasibility Study are suggested to be conducted in order to further evaluate the foundation conditions and slope stability along and around the proposed project structure areas, as shown briefly below.

1) To explore and evaluate subsurface conditions of the project sites for the development of the ROR-type hydropower projects.

2) To provide geotechnical data and parameters necessary for geotechnical analyses and design of the proposed projects in the Feasibility Study.

3) To confirm and provide solution against geological hazards or problems that may arise due to subsurface conditions.

The geological and geotechnical investigation works is suggested to consist main of 1) Detailed geological mapping around the main project structure sites, 2) Boring investigation and related in-situ tests, and 3) Laboratory test for foundation rocks. Table 5.1 gives the recommended boring investigations and relevant in-situ tests.


5-4

Table 5.1 Recommended quantity of boring investigation for feasibility study

Area/Site Borehole No.

Drilling depth (m)

Lugeon test (section)

SPT test (time)

Rock core sample

BW-1 20 4 10 3 Weir BW-2 20 4 5 3

BW-3 20 4 10 3

Intermediate pond dike

BD-1 30 5 15 3 BD-2 20 3 10 3 BD-3 30 5 15 3

Connection tunnel alignment

BC-1 40 5 - 4 BC-2 60 15 - 5

Headrace tunnel alignment

BH-1 80 15 0 4 BH-2 80 15 0 5 BH-3 80 15 0 5

Surge tank - - - - -

Penstock BP-1 20 - 10 3 BP-2 20 - 10 3

Powerhouse BP-3 20 - 5 3 Total 13 bores 400 90 90 50

Appendix A

List of Earthquakes around the Project Site

Appendix A List of Earthquakes around the Masang-2 Project

Latitude Longitude Focus Depth DistanceS E (Km) (Km)

1 1973 -1.70 99.68 33 5.9 Ms 1832 1973 -1.76 99.66 33 5.3 Ms 1903 1973 -1.75 99.66 33 5.0 mb 1894 1973 -1.47 99.85 51 5.9 mb 1535 1973 -1.35 100.63 33 5.0 mb 1416 1974 0 41 98 66 33 5 0 mb 186

MagnitudeNo. Year

6 1974 0.41 98.66 33 5.0 mb 1867 1975 -1.65 99.72 18 5.4 mb 1768 1975 -1.47 99.74 33 5.1 mb 1579 1976 -1.76 99.45 33 5.0 mb 199

10 1976 -1.36 100.04 33 5.2 mb 13611 1977 1.58 99.86 178 5.6 mb 19612 1977 0.45 100.02 22 6.0 Ms 7013 1977 0.67 98.68 40 5.5 mb 19514 1977 0 48 98 73 13 5 5 b 18114 1977 0.48 98.73 13 5.5 mb 18115 1978 -1.68 99.71 33 5.3 mb 18016 1979 0.69 98.91 72 5.3 mb 17417 1979 0.54 98.78 72 5.8 mb 17918 1979 -1.08 100.96 131 5.4 mb 13119 1979 -1.93 100.40 50 5.1 mb 19920 1980 0.61 100.10 158 5.1 mb 8521 1980 -1.75 100.51 65 5.1 mb 18122 1981 -1.01 100.29 54 5.2 mb 9623 1981 -1.53 100.59 76 5.4 mb 15824 1983 -1.80 99.60 27 5.3 mb 19725 1983 1.11 100.06 209 5.1 mb 14126 1984 -0.91 100.01 101 5.2 mb 8827 1984 -1.07 99.95 75 5.4 mb 10728 1984 -0.96 99.82 80 5.0 mb 10129 1984 0.96 98.91 109 5.0 mb 19230 1986 -0.85 99.90 82 5.3 mb 8631 1986 -0.68 99.97 90 5.3 mb 6632 1986 0.11 100.24 46 5.3 Ms 2933 1987 -1.33 99.61 45 5.2 Ms 14934 1988 0.93 99.10 116 5.0 mb 17435 1988 0.58 98.60 60 5.1 mb 19936 1988 -1.10 99.94 77 5.0 mb 11137 1988 -1 34 100 75 104 5 0 mb 14437 1988 -1.34 100.75 104 5.0 mb 14438 1989 0.50 100.11 176 5.0 mb 7339 1989 1.01 98.87 110 5.1 mb 19940 1990 -0.36 99.14 68 5.0 mb 12441 1990 -0.12 99.52 111 5.1 mb 8042 1990 -1.60 99.48 57 5.2 mb 18243 1990 -1.90 100.10 68 5.4 mb 19544 1990 -0.23 99.14 73 5.0 mb 12245 1991 1 88 100 40 67 5 0 b 19345 1991 -1.88 100.40 67 5.0 mb 19346 1991 -0.35 99.32 63 5.2 mb 10447 1991 -1.07 99.84 53 6.2 Ms 11148 1992 0.17 98.65 75 5.0 mb 18049 1993 -1.63 99.61 31 6.5 Mw 17950 1993 -1.68 100.57 68 5.3 mb 17451 1994 -0.59 98.60 29 5.6 Mw 18852 1994 -1.05 100.36 102 5.1 mb 10153 1994 -1.72 99.79 41 5.1 mb 18154 1994 -0.52 99.16 64 5.1 mb 12655 1994 -1.08 100.29 86 5.2 mb 104



MagnitudeNo. Year

56 1996 0.86 99.46 110 5.0 mb 14157 1997 -1.87 99.74 33 5.4 Mw 19958 1998 -0.54 99.26 55 7.0 Mw 11759 1998 -1.68 99.56 33 5.1 Mw 18660 1999 1.28 100.32 211 6.2 Mw 15961 1999 -0.45 99.63 79 5.3 mb 7561 1999 0.45 99.63 79 5.3 mb 7562 2000 -1.23 98.88 33 5.0 mb 19363 2000 -1.71 100.58 47 5.0 mb 17864 2001 -0.20 99.25 77 5.6 Mw 11065 2001 0.88 98.94 80 5.2 Mw 18466 2001 0.29 98.54 33 5.1 Mw 19467 2002 -0.50 98.68 33 5.1 Mw 17768 2003 0.54 98.60 45 5.5 Mw 19769 2003 0 54 100 82 144 5 7 Mw 7869 2003 -0.54 100.82 144 5.7 Mw 7870 2003 -1.38 99.79 21 5.0 mb 14671 2004 -0.47 100.65 55 5.1 Mw 5872 2004 -1.56 100.49 42 6.0 Mw 15973 2004 -1.55 100.54 65 5.5 Mw 15974 2004 0.11 98.73 59 5.2 Mw 17075 2005 -0.13 98.73 47 5.8 Mw 16776 2005 -1.57 99.42 17 5.3 Mw 18277 2005 -1.65 99.45 20 5.0 mb 18878 2005 -1.64 99.61 19 6.7 Mw 18079 2005 -1.61 99.58 30 5.3 mb 17880 2005 -1.61 99.62 30 5.7 mb 17681 2005 -1.46 99.26 30 5.0 mb 18282 2005 -1.68 99.78 27 5.2 mb 17883 2005 -1.71 99.78 30 6.5 Mw 18184 2005 -1.62 99.59 30 5.5 mb 17985 2005 -1.71 99.72 29 5.8 Mw 18386 2005 -1.71 99.87 25 5.0 mb 17887 2005 -1.63 99.64 23 5.6 Mw 17788 2005 -1.64 99.70 21 5.3 mb 17689 2005 -1.78 99.93 32 5.5 Mw 18490 2005 -1.62 99.64 30 5.3 Mw 17691 2005 -1.65 99.62 30 5.3 Mw 18092 2005 -1 83 99 78 27 5 2 Mw 19492 2005 1.83 99.78 27 5.2 Mw 19493 2005 -1.59 99.72 30 6.4 Mw 17094 2005 -1.70 99.80 23 5.0 Mw 17995 2005 -1.64 99.80 28 5.0 Mw 17396 2005 -1.69 99.86 23 5.0 mb 17697 2005 -1.71 99.74 30 5.4 mb 18298 2005 -1.66 99.64 30 5.0 mb 18199 2005 -1.76 96.85 33 5.1 Mw 416

100 2005 1 59 99 45 22 5 2 Mw 182100 2005 -1.59 99.45 22 5.2 Mw 182101 2005 -1.76 99.80 30 5.2 Mw 185102 2005 -1.71 99.85 30 5.2 Mw 179103 2005 -1.71 99.88 31 5.0 Mw 178104 2005 -1.91 99.95 33 5.7 Mw 198105 2005 -1.77 99.94 29 5.0 Mw 183106 2005 -1.63 99.62 21 5.4 Mw 178107 2005 0.35 98.57 30 5.0 Mw 193108 2005 0.45 98.67 40 5.0 mb 186109 2005 -1.66 99.62 29 5.0 Mw 181110 2005 -1.20 99.78 30 5.2 mb 127111 2006 1.12 99.59 14 5.3 mb 158



MagnitudeNo. Year

112 2006 0.63 99.86 30 5.8 Mw 96113 2007 -0.49 100.50 19 6.4 Mw 48114 2007 -0.49 100.53 11 6.3 Mw 50115 2007 -0.40 100.91 20 5.0 Mw 80116 2007 -1.90 99.82 16 5.7 mb 200117 2007 -1.88 99.72 29 5.1 mb 201117 2007 1.88 99.72 29 5.1 mb 201118 2007 -1.69 99.67 28 6.5 Mw 182119 2007 -1.61 99.64 29 5.1 mb 175120 2007 -1.72 99.64 32 5.5 mb 187121 2007 -1.76 99.72 35 5.0 Mw 188122 2007 -1.80 99.54 30 5.0 mb 199123 2007 -1.57 100.07 35 5.4 Mw 159124 2007 -1.77 100.46 35 5.3 Mw 182125 2007 1 79 99 49 26 6 1 Mw 200125 2007 -1.79 99.49 26 6.1 Mw 200126 2007 -1.85 99.78 35 5.1 mb 196127 2007 -1.74 99.48 27 5.9 Mw 196128 2007 0.76 98.75 75 5.0 mb 193129 2007 -0.55 99.47 35 5.5 Mw 96130 2007 -0.88 100.69 107 5.0 Mw 96131 2007 -1.63 100.44 35 5.3 mb 166132 2008 -0.16 99.19 81 5.3 mb 116133 2008 -1.07 99.79 84 5.3 Mw 114134 2008 -0.25 100.14 126 5.1 Mw 16135 2009 -1.59 99.73 35 5.0 mb 170136 2009 0.07 100.04 127 5.0 Mw 32137 2009 0.48 98.55 35 5.4 Mw 200138 2009 -1.20 98.79 44 5.0 mb 199139 2009 -1.05 100.33 35 5.1 Mw 101140 2009 -1.48 99.49 20 6.7 Mw 170141 2009 -1.55 99.42 10 5.4 mb 180142 2009 -1.45 99.43 21 5.8 Mw 170143 2009 -1.57 99.43 10 5.0 mb 182144 2009 -1.46 99.40 10 5.2 mb 173145 2009 -1.38 99.55 30 5.0 Mw 157146 2009 -1.44 99.45 10 5.0 mb 168147 2009 -1.37 99.37 10 5.5 Mw 166148 2009 -1 42 99 48 10 5 0 Mw 164148 2009 1.42 99.48 10 5.0 Mw 164149 2009 -1.65 99.57 18 5.4 Mw 182150 2009 -1.36 99.47 10 5.2 mb 159151 2009 -0.72 99.87 81 7.5 Mw 75152 2009 -0.73 100.13 83 5.4 mb 66153 2009 -1.74 100.54 73 5.0 mb 180154 2009 -1.43 99.39 19 6.0 Mw 171155 2010 -0.32 99.09 63 5.2 mb 129156 2010 0 74 99 79 88 5 4 mb 82156 2010 -0.74 99.79 88 5.4 mb 82157 2010 1.00 99.54 42 5.3 mb 149158 2010 -1.35 99.53 35 5.0 mb 155

Appendix B

Interpreted Seismic Profiles

part 14 geological survey for masang-2 heppgeological mapping was conducted with a topographical map...

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