Application of Geophysical Method in Engineering and Environmental Problems

Abstract

Geophysical surveys (2‐D resistivity imaging and seismic refraction) were conducted in Tanjung Tokong, Penang and Gunung Keriang, Kedah. Tanjung Tokong is a reclaimed area which is under construction for building 24 floors moderate apartment. Subsurface boulders and unknown materials in reclaimed layer have caused problems in construction of the structural foundation in the area. The objective of the study at Tanjung Tokong is to obtain subsurface information that include the depth to bedrock, boulders, composition of subsurface structures and to map the flow of subsurface water by using 2‐D resistivity imaging and seismic refraction method. Gunung Keriang is a limestone area with karst characteristics such as cavity and pinnacle. These features may be a threat to human’s life and could cause damage to properties. The objective of the study at Gunung Keriang is to detect cavities, pinnacles, fractures and void that may formed in limestone area by using 2‐D resistivity imaging method. In Tanjung Tokong, the subsurface consist of two layers. The first layer refers to the reclaimed land with mixture of boulder. The second layer has saltwater intrusion and granite bedrock at 17 meter depth. In Gunung Keriang, the cavity was detected at 180 meter in survey Line 2 while two pinnacles were detected at 80 meter and 170 meter in survey Line 3. Both geophysical methods were used successfully in providing subsurface information to the engineers.