Bulletin of the Geological Society of Malaysia, Volume 43, Dec. 1999, pp. 215 – 225
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 of three 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.