CEOSEA '98 ProceerJiI1/IJ, Ceo/. Soc. !/1a/aY"la BII//. 45, December 1999; . 215-225

Ninth Regional Congress on Geology, Mineral and Energy Resources of Southeast Asia - GEOSEA '98

GEOSEA '98

17 - 19 August 1998 • Shangri-La Hotel, Kuala Lumpur, Malaysia

The use of electrical and seismic methods for imaging shallow subsurface structure of limestone at Batu Caves,

Kuala Lumpur, Malaysia

ABDUL RAHIM SAMSUDIN, MOHAMMED 1. ABu SHARIAH AND U MAR HAMZAH

Department of Geology Universiti Kebangsaan Malaysia

43600 UKM Bangi Selangor D.E., Malaysia

Abstract: Geoelectrical resistivity and seismic surveys were conducted to investigate subsurface structure of a selected limestone area at Batu Caves, Kuala Lumpur. The limestone in the area belongs to the Kuala Lumpur Limestone formation . The formation generally show two geomorphologic expressions, one above the ground and the other buried beneath alluvium. The buried limestone shows highly irregular karst topography with pinnacle structures. These features have caused a variety of geotechnical problems in both the design and construction of structural foundation in the area.

Two dimensional (2-D) geoelectrical imaging survey was carried out along two traverses by using ABEM SAS 300C Terrameter. The first traverse which comprises ofthree resistivity profiles with a total length of 144 meters was established by using Wenner configuration, and the second traverse was located on cavities at depth ranging from 15 to 26 meters below ground.

Result of the two dimensional resistivity inverse model of the first traverse indicates an anomalous area of low resistivity in the middle (approximately 50 m width) and high resistivity at both ends of the traverse. The subsurface low resistivity anomaly is interpreted as buried channel at shallow depth and the high resistivity is associated with massive pinnacle limestone bedrock. The second traverse has also detected the presence of water-filled cavities which are indicated as zones of low resistivity in the inversion model.

Seismic refraction and reflection surveys conducted on both of the traverses substantiate the presence of pinnacle structures and possible channel in the limestone of the first traverse and cavity filled up with water in the second traverse.

INTRODUCTION

Geophysical methods allow subsurface conditions to be examined indirectly, quickly, cheaply, and reliably with sufficient results. The methods utilize different physical properties of the earth materials to study subsurface structure. Two dimensional geoelectrical resistivity and seismic imaging are two geophysical techniques which are now widely used in geotechnical and environmental studies. The contrast in geoelectrical conductivity between the limestone bedrock and soil cover as well as water-filled cavities can produced a measurable change in the apparent resistivity especially for shallow bedrock. The seismic refraction method is the most widely used geophysical technique for shallow subsurface investigation (Burger, 1992; Abdul Ghani Rafek and Gred Duplitzer, 1988) whereas the seismic

reflection method has been used for underground exploration for deeper target (Miller et al., 1993; Steeples and Miller, 1993). Many case studies illustrate the use of shallow seismic reflection method in detecting fault, cavities, and alluvial deposit at shallow depth. The technique has been used successfully in mapping bedrock topography beneath alluvium in the vicinity of hazardous waste sites (Steeples and Miller, 1993).

Buried karstic limestone with pinnacles, cavities, and overhang structures can caused considerable geotechnical problems during constructions offoundation structures (Ting, 1986). It is therefore necessary to determine the nature of the subsurface structure of the limestone bedrock to ensure a proper design of foundation as well as for remedial work purposes. Geophysical and geological studies were conducted by Soepadmo and Hua (1971) and Jamaludin Othman (1995a) to

216 ABDUL RAHIM SAMSUDIN, MOHAMMED I. ABU SHARIAH AND UMAR HAMZAH

investigate the subsurface karstic feature of the limestone beneath alluvium at Batu Caves, Kuala LUlb.pur

This paper describes the results of seismic and geoelectrical resistivity imaging of subsurface structure oflimestone at an abandoned JKR quarry of Batu Caves, Kuala Lumpur.

GEOLOGICAL SETTING

The study area is located south of the Batu Caves limestone hill (Fig. 1). The site is relatively flat with the limestone bedrock covered by an alluvial deposit. The Batu Caves limestone has fOrnied a karstic topographic hill with the highest elevation at about 200 m (Ibrahim Komoo, 1989). Figure 2 shows the geological map of Kuala Lumpur and its surrounding area. The limestone in the Batu Caves area belongs to the Kuala Lumpur Limestone formation. Generally, it composes of fine to coarse-grained white to gray calcitic and dolomitic marble. Figure 3a shows a north-south section of the limestone hill and bedrock covered by the a:TIuvial deposits with thicknesses ranging from few to several tens of meters.

Geologically, the limestone is interpreted to have been uplifted, compressed, folded, and heated into a mosaic of large crystals which had changed to marble in most places during the Triassic period (Soepadmo and Hua, 1971). The rock was deposited originally in shallow warm water and dry climatic condition:s.

Previous studies indicated that the carbonate rocks are karstifiable (Bogli, 1980) and those buried beneath the river alluvium usually forms high­relief karstic topography (Fig. 3b, Yeap (1986». The katstic topography with pinnacles and channels have created major foundation problems (Ibrahim Komoo, 1989) in the study area.

The Geological Survey Department of Malaysia has drilled several bore holes in the study area (Jamaludin Othman, 1995b). The drilling records (Fig. 4) indicate that the subsurface geology of the survey area is mainly made up of three layers. The first layer corresponds to a relatively thin humid s·oil and the second layer is alluvium which comprises slightly brownish to white clay, silty sand with traces of muscovite and fine quartz grains. The third layer corresponds to light grey limestone bedrock showing several cavities at depth of ranging from 15 to 26 meters under ground.

FIELD SURVEY

Geoelectrical resistivity and both seismic refraction and reflection surveys were conducted along two selected traverses. Location of the

traverses is shown in Figure 5. An ABEM Terraloc 24-Channel Seismograph

was used in the seismic data acquisition with geophone spacing of 3-meters. Geophones with natural frequency of 14 Hz, and a 10-kg sledgehammer source energy were used to perform the refraction and reflection surveys. Seismic refraction was carried out on both traverses using thirteen shots configuration system and common depth point (CPD) reflection survey was conducted with 15 meters offset shot.

ABEM SAS 300C Terrameter was used to collect the geoelectrical resistivity imaging data with 50-electrodes system connected to a multicore cable and switch box. The box switching unit was used to select electrode numbers and electrode spacing during measurements manually. Each measurement was made with Wenner array and the same measurement was repeated with increasing electrode spacing.

The first traverse which consists of three geoelectrical resistivity and three seismic profiles was established in an area of suspected subsurface pinnacles structure. Geoelectrical resistivity imaging was conducted along the first traverse with a total length of 144 meters. Figure 5 shows the first resistivity traverse which comprises of three overlapping electrical resistivity profiles AB, CD, and BC. The length of profiles AB and CD were 98 and 96 meters respectively with electrode spacing of 2 meters. The third profile BC was carried out on the middle ofthe traverse line with its mid point located at E. An electrode spacing of one meter was used for this profile with total length coverage of 49 meters.

Two seismic refraction profiles 88' and 8'8" were carried out along the first traverse line. The length of each profile was 69 meters. A common depth point (CDP) seismic reflection survey was also conducted along the same traverse line with first geophone located at 8 as illustrated in Figure 5. The total coverage length of the seismic reflection profile was 75 meters.

For the second traverse line, three different geophysical profiles were established. The first profile is a geoelectrical resistivity imaging profile with electrode spacing of2 meters and a total length of 98 meters. The second seismic refraction profile LL' was conducted with total length of 69 nieters. The third CDP seismic reflection profile was established along the same traverse line, where the location of the first geophone lies at L as illustrated in Figure 5. A total coverage length of the CDP seismic reflection profile was 75 meters.

The measured apparent resistivity values of the geoelectrical resistivity imaging profiles were interpreted by using two dimensional resistivity

GEOSEA '98 ProceeJillgJ (GSM Bllll. 45)

EECTRICAL AND SEISMIC METHODS FOR IMAGING SHALLOW SUBSURFACE STRUCTURE OF LIMESTONE AT BATU CAVES 217

. 4120COE

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...... scm ,. :25~006

Figure 1. Location map of the survey area.

LEGEND:

~ QUARTZ DYKE

[II GRANITE

B KENNY HILL FORMATION

~ KUALA LUMPUR LIMESTONE

IIIIII!II HAWTHORNDAN SCHIST

~ DINDING SCHIST

/" FAULT

r' ROCK BOUNDARY

/.}v STRIKE AND DIP

== ROAD

[4S FOLIATION

Figure 2. The geology of Klang Valley-Kuala Lumpur area (after Fatt and Pee, 1986).

December 1999

1,000 It 1,000 It

BATU CAVES

500ft

SUBANG

Oft--- - ------------- ---- -- --- - ---- ------- --- ---- - - - - -- - ---- -Oft-LIMESTONE AREA

PROFILE THROUGH THE NORTH KUALA LUMPUR AREA - 300 It -300 It

Figure 3a. Profile illustrates the common karstic topography expression through Subang to Batu Caves, north Kuala Lumpur (after Yeap, 1986).

CLIFF OVERHANG

PINNACLE CAVITY

FLOATER

:::::::: :::: : ...... ..... .. .. ... ... .. , .. ... .. ....... . .. .... .... -... . ... ... ... .. .... .... .. ......... :ALLUVIUM:

.. ........... . ..

Figure 3b. Some features of subsurface karstic limestone bedrock in the Kuala Lumpur area (after Fatt and Pee, 1986).

Depth (m) (a) (b) Depth (m)

00.00 r'""""",,",,~""'~- Weathering soil (Humid soil) ---------F_:r;:;;;~~1;I! 8·0 .3

Brownish whity silty clay with trace of muscovite (Alluvium deposits)

15.1 0 ~.;;;;. __ Whitish gray with lines of pink fair to limestone

15.70 __ Cavity filled up with sediments

17.80 __ Light gray with pink lines fair to limestone ---.....g;

20.20 21.1 0 =~F§;~~~ __ Cavity 21.40 -- Whitish gray limestone

-- Cavity filled up with water

9.3

19.6

Figure 4. The geological log ofthe boreholes in the survey area, (a) borehole No.6 and (b) borehole No.2.

EECTRICAL AND SEISMIC METHODS FOR IMAGING SHALLOW SUBSURFACE STRUCTURE OF LIMESTONE AT BATU CAVES 219

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December 1999

220 ABDUL RAHIM SAMSUDIN, MOHAMMED I. ABU SHARIAH AND UMAR HAMZAH

inversion program "RES2DINV" (Loke, 1997). Whereas the seismic refraction and reflection data were interpreted by using "Biasan" an d "Eavesdropper" softwares respectively.

RESULTS AND DISCUSSION

First traverse line

Results of the interpreted 2D electrical resistivity profiles AB, CD, and CB along the first traverse line are shown in Figures 6, 7, and 8 respectively.

The measured apparent res istivity pseudosection and computer inverse model resistivity sections of profile AB are shown in Figure 6. The inverse model section shows a thin layer of low resistivity zone on the right side of section. The low resistivity anomaly is interpreted as corresponds to water saturated alluvial deposits . It is underlain by a high resistivity zone described as limestone bedrock with a sharp margin of the pinnacle structure at approximately below 50 meters mark. The resistivity on the left side of the section at 50 to 98 meter marks is relatively low with values between 30 Qm to 600 Qm. An elongated shape of

the anomalous low resistivity contour suggests the presence of water saturated buried channel.

The calculated apparent resistivi ty pseudosection and computer inverse model section of the second profile CD are shown in Figure 7. The low resistivity value (3 0 to 600 Qm) observed on the right side of the section is associated with alluvial deposits and possibly related to the buried channel. The inverse model also shows a possible small cavity filled up with water on the left side of the section approximately under 62 to 66 meter marks. The high resistivity limestone bedrock lies beneath the alluvial deposits at shallow depth with pinnacle structure located approximately below 50 meter mark.

The measured and inverse sections of the third profile BC are shown in Figure 8. The pseudosection and inverse model show resistivity values of less than 600 Qm which is related to the alluvial materials. The low resistivity anomaly ofless than 30 Qm represents the water saturated buried channel.

A single 2-D resistivity subsurface model was produced for the first traverse line by overlapping results of the two resistivity inverse models for profiles AB and CD as illustrated in Figure 9. The resistivity subsurface model shows high resistivity

A 98 meters --,--,----,-_---::-::-_-,--____ 8 ---Fle-rnical-' -Ls-u-b-·.-ity-Prafile--No.-l-, haw...., U- No.1. Bat.. c- -:r.'IraLqria

Pseudo Depth 9.9 16.0 32.0 48.0 64.9 80.0 96.9 N.

1.9 2.9 3.1 4.1 5.1 6.1 7.2 8.2 9.2

UI.2 11.3 12.3 13.3 14.3 15.4

MeasUPed Apparent Resistivity Pseudosection

Iteration 6 ~ error = 19.1 X Depth 9.9 16.0 32.0 48.9

9.5 1.5 2.8

4.3

6.3

8.7

11.7

15.5

Unit Electrode Spacing 2.9 M.

64 . 9 89 . 9 96.9 ...

c:::J c=J c::J t ",,'1 t ····-·-·-·l !"",,) II/lIIlIII _ IIiIIII __ 15.1 52.7 184 643 2247

Inverse Model Resistivity Section OHM.M Unit Electrode Spaci n g = 2.9 M.

Figure 6. The pseudosection and the resistivity inverse model of profile AB carried out along the first traverse line.

CEOSEA '98 P,."C<,aJill.I},/ (CSIH BII II. -Dj

EECTRICAL AND SEISMIC METHODS FOR IMAGING SHALLOW SUBSURFACE STRUCTURE OF LIMESTONE AT BATU CAVES 221

C ___________ 96 meters ___ _ _____ _ D Pseudo l.Iecirio:alll.esiriiritr Pnfili, Ne.2, u....-e u- Ne. L Bat. c- -~

Depth Q . Q 16.0 32.0 48.9 64.0 89.9 ~6.Q M. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

1.0 2.& 3 . .1 4.1 5.1 6.1 7.2 8.2 9.2

1&.2 11.3 12.3 13.3 14.3 15.4

Measured Apparent Resistivity Pseudosection Unit Electrode Spacing = 2.& M.

Depth &.5 1.5 2.8

4.3

6.3

8.7

11.7

15.5

Iteration 6 RMS error = 29.8 Yo 0.0 16.0 32.0 48 .9 64.& 8&.& 96.& M.

c:::J c::J c::J ti ",' 1 1--.- .... ---1 1'''''3 _I11IIIliliiii __ 4.1 24.3 146 877 5267

Inverse Mo~J Resistivity Section OHM.M Unit £lectFOde Spacing = 2.9 M.

Figure 7. The pseudosection and the resistivity inverse model of profile CD carried out along the first traverse line.

C ~m~~ B --------------------------- ---------------------------BaedBral~ PI.fiIIo Ne.l, L-.- I.i:ne N...l. Bat.. C----JIalapia 9.0 17.0 25.9 33.9 41.& 49.9 M. Pseudo

Depth .1.9 ~-L~~-L~~~~~~~-L~~~~-L~~-L~~J-~-L~~-L~~J-~-L~~

&.5 1.& 1.5 2.0 2.6 3.1 3.6 4.1 4.6 5.1 5.6 6 . .1 6.7 7.2 7.7

Measu.ed Apparent Resistivity Pseudosection

Iteration 5 ~ error = 7.2 Yo Depth 1.9 9.0 17.0 25.9

&.2 &.8 1.4

2.2

3.1

4.3

7.7

. . . . . . . ... ....... .

Unit Electrode Spacing 1.11 M.

33.9 41.9 49.9 M.

[:=:J c::=J c:J 11 "",1 t·-·-·-·--! 1"'''4IIIIIIII Hal ..... __ 18.9 43.9 192 236 548

Inverse Model ResistiYity Section OHM.M Unit Electrode Spacing = 1.& M.

Figure 8. The pseudosection and the resistivity inverse model of profile CB carried out along the first traverse line.

Model Resistivity Section OHM. M

Buried Channel filled up with sediments

1 4

Unit Electrode Spacing = 2.0 M.

Figure 9. 2-D geoelectrical resistivity inverse model of the first traverse produced by overlapping of the profiles AB and CD.

s=:)

10910 10920 10930 10940 10950 10960 10970 10980. 0.0

o

.0

.0

Figure 10. CDP shallow seismic reflection section of the first traverse line.

D

I\) I\) I\)

» CD o c ,. :rJ :t> :r: ~ (J) :t> s:: (J) c o Z :s:: o :r: :t> s:: s:: m o

» CD C

(J) :r: :t> ::D l> :r: :t> z o C s:: :t> ::D

:r: :t> s:: N » :r:

EECTRICAL AND SEISMIC METHODS FOR IMAGING SHALLOW SUBSURFACE STRUCTURE OF LIMESTONE AT BATU CAVES 223

anomalies of limestone bedrock at both sides of the traverse line. The limestone bedrock shows highly irregular subsurface topography with pinnacle structures. A synclinal shape resistivity contours interpreted as swallow hole is observed on the left side of the model. The low resistivity zone at the middle of the model is likely corresponds to a possible water saturated buried channel within the alluvial sediments as a result of mining activities. High resistivity suggests that the limestone bedrock was exposed at shallow depth on both left and right sides of the section.

A CDP seismic reflection section of the first traverse (Fig. 10) shows a strong discontinuous reflector that is located approximately between 15 to 30 ms two-way time with an area of weak reflection between station 10,942 and 10,960. The poor reflection data quality coincides well with the resistivity interpreted buried channel. Another strong reflector is observed between 35 and 55 ms two-way time and a zone of poor reflector between station 10,920 and 10,940 which probably related to a possible cavity. The seismic section shows that the first and second reflectors have undergone some

displacement which probably associated with slow subsidence or sinkhole caused by chemical dissolution.

The interpreted seismic refraction sections of profile 88' and 8'8" observed three subsurface geological layers which agree well with the bore hole data. The top layer refers to a humid soil with compressional P-wave velocity ranges from 200 mI s to 600 mls. The thickness of this layer varies from 0.1 to 2.4 m . The P-wave velocity of the second layer ranges from 1,024-1,754 mls with layer thickness ranges from 0.2 to 15.2 m. This layer is associated with alluvial deposits. The bedrock was represented as the third layer with P -wave velocity ranges between 2,782 to 3,528 mls.

Second traverse line

A 2-D resistivity inverse model of the second traverse (Fig. 11) shows a relatively low resistivity anomaly which is interpreted to be a buried channel which extends beyond 15 meters depth. The model also shows a rounded shape of low resistivity anomaly which is related to swallow hole filled up with alluvial deposit . Elongated anomaly on the

Second Traverse Line ( 98 meters)

Ps d DATU CIWE, LINE flO . 2 n::t~ 9.~9~~~~~L6~.9~~~LL3~2~._9~~~~4~8_·L9~~~~6~4~·L9~~~~8L0~.0~~~~9~6~.~0 M.

1.9 2.1it 3.~ 4.~ 5.1. 6.1 7.2 8.2 9.2 ~9 . 2 11.3 12.3 13.3 14.3 15.4

Measured Apparent Resistivity Pseudosection

Iteration 4 RMS error = 20.8 Yo

Depth 9.9 16.9 32.9 48.9

0.5 1.5 2 . . 8

4 . 3

6.3

8.7 1 11. 7

15.5

Unit Electrode Spacing = 2.9 M.

64.9 80.0 96.0 M.

C=:I c::J c:::J 1"",,1 F·-"·-·-:J €""i) _ IBBB I11III __ 2.9 19.2 125 814 5393

Invell'Se Model Resistiuity Section OHM.M Unit Electrode Spacing = 2.1it M.

Figure 11. The apparent resistivity pseudosection section and the geoelectrical resistivity inverse model section of Wenner configuration carried out along the second traverse line.

Deccm f,u] 999

224 ABDUL RAHIM SAMSUDIN, MOHAMMED I. ABU SHARIAH AND UMAR HAMZAH

right side of the model is interpreted to be a small cavity filled up with water. High resistivity zone located under the cavity is interpreted as the limestone bedrock. The limestone bedrock in the left side of the inversion model shows the pinnacle structure at shallow depth.

A multifold CDP shallow seismic reflection section of the second traverse (Fig. 12) shows a strong and continuous first reflector between 18 and 25 ms two-way time. Second strong and discontinuous reflector of anticlinal structure is located approximately between 38 to 52 ms two­way time. The seismic section shows an absence of second reflector between station 10,840 and 10,860. The strong reflection event is interpreted as being the top uf' the limestone bedrock, whereas the underlying zone of no reflection illustrates the presence of cavity at shallow depth which is in good agreement with the resistivity model and boreholes information. Two short strong reflectors appear between 50 to 55 ms and 60 to 68 ms two-way time on the right side of the section. Below 65 ms two way time a zone of poor reflection is observed for a highly irregular subsurface layer of the karstic limestone bedrock. The seismic section shows the system of displacements that are located around station 10,835 to 10,855 and between 18 to 65 ms two-way time associated with sinkhole or slow subsidence.

The interpreted seismic refraction section indicates the compressional wave velocity of the top layer varies from 243 to 833 m/s. The thickness of this layer ranges from 0.1 to 2.3 meters and represents the top soil. The second layer having a compressional wave velocity of 1382 m/s with

L:=)

thickness of 0.2 to 14.6 meters is associated with alluvial deposits. The high velocity layer corresponds to limestone bedrock. The compressional wave velocity of the limestone bedrock is around 3,700 mls . The subsurface geological section shows no refraction between 36-42 meters marks and this is interpreted as cavity which is in good agreement with the previous results .

CONCLUSION

In conjunction with bore hole data , the geoelectrical resistivity and seismic techniques have been successfully used to image the complex subsurface karstic features ofthe limestone at Batu Caves, Kuala Lumpur.

The two dimensional geoelectrical resistivity images indicate the presence of buried channel running across the study area. The resistivity technique also detected the irregular subsurface topography ofthe pinnacle karstic limestone bedrock and swallow hole filled up with alluvial sediments as well as cavities.

The seismic technique on the other hand provide true depth of the limestone bedrock, subsurface geological profiles and location of the cavities and buried channel which are indicated as zone of no reflection in the seismic sections. However, these techniques require bore hole information before any meaningful interpretation can be made. The interpreted seismic section reveals that the limestone bedrock has been displaced probably due to the development of sinkhole or subsidence in the area.

10840 10850 10860 10870 10880 10890 10900

Rl- -

40.0

R3 60.0

80.0ms

Figure 12. CDP shallow seismic reflection section of the second traverse line.

GEOSEA '98 p,.ocecdin.9J (GS/y/ BllLL. 45)

EECTRICAL AND SEISMIC METHODS FOR IMAGING SHALLOW SUBSURFACE STRUCTURE OF LIMESTONE AT BATU CAVES 225

ACKNOWLEDGEMENT

The authors wish to thank Universiti Kebangsaan Malaysia for research grant No. S/l1/ 96. We are grateful to Mr. Tajul Arus Othman and undergraduate students for assistance in geophysical field data collection. We are thankful to Mr. Jamuldin Othman and Geological Survey Malaysia (GSM) for providing reports used in this study. We are grateful to Dr. Abdul Ghani Rafek (UKM), Dr. Shahrin Ibrahim (UPM), Dr. M.H. Loke (USM), Mr. B.H. Lee, and everybody involved for their help, time and advice in this study.

REFERENCES

ABDUL GHANI RAFEK AND GRED DUPLITZER, 1988. Determination of the Location and Extent of Karst in Limestone with Use of Geophysical Methods. ASEG/SEG Conference -Adelaide, 338-342.

BOCLl, A, 1980. Translated by: Schmid, June. Karst hydrology and physical speleology . Spring-Verlag Berlin Heidelberg, Germany.

BURGER, H.R, 1992. Exploration Geophysics of the Shallower Subsurface. Prentice Hill, UK.

FAIT, C.S. AND PEE, H.L., 1986. Pile Foundation in Limestone Areas of Malaysia. Paper in Foundation Problems in Limestone Areas of Peninsular Malaysia, 25-36.

IBRAHIM KOMoo, 1989. Engineering Geology of Kuala Lumpur,

Malaysia. Proceedings of the international conference on engineering geology in tropical terrains, 262-273.

JAMALUDIN OrHMAN, 1995a. Regional Gravity Survey of the Batu Caves Area, Selangor (Component 1). Report No. GF 07/95, Geological Survey Malaysia, Ipoh-Malaysia.

JAMALUDIN OrHMAN, 1995b. Microgravity Survey for Cavity Detection in Limestone at Batu Caves Area, Selangor (Component 2). Report No. GF 08/95, Geological Survey Malaysia, Ipoh-Malaysia.

LaKE, M.H., 1997. Electrical Imaging Surveys for Environmental and Engineering Studies. Universiti Sains Malaysia.

MILLER, RD., STEEPLES, D.W., HILL, RW., JR., AND GADDIS, B.L., 1993. Identifying Intra alluvial and bedrock structures shallower than 30 meters using seismic reflection technique. Paper in Geotechnical and Environmental Geophysics, VIII, Society of Exploration Geophysics -USA 2nd edition, 89-97.

SoEPADMO, E. AND HUA, H.T., 1971. A guide to Batu Caves. Art Printing Works, Kuala Lumpur-Malaysia.

STEEPLES, D. AND MILLER, RD., 1993. Seismic Reflection methods applied to Engineering Environmental and Ground Water. Paper in Geotechnical and Environmental Geophysics, VI, Society of Exploration Geophysics - USA 2nd edition, 1-30.

TING, W.H., 1986. Foundation Problems in Limestone Areas. The Geotechnical Engineering Division of Institution of Engineer-Malaysia.

YEAP, E.B., 1986. Irregular Topography of Subsurface Carbonate Bedrock in the Kuala Lumpur Area. Paper in Foundation Problems in Limestone Areas of Peninsular Malaysia, 1-12.

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Mallllscript received 14 December -1998

December 1999