MEASUREMENT DATA INTERPRETATION OF ELECTRICAL RESISTIVITY TOMOGRAPHY (ERT) AND SELF-POTENTIAL (SP) IN COLORADO SCHOOL OF MINES (CSM) INTRAMURAL FIELD NORTH RELATED TO THE PRESENCE OF AQUIFERS

• Main Author: Lail Fauzan, Lulu
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/60602
• Institution: Institut Teknologi Bandung

Measurement data of Electrical Resistivity Tomography (ERT) and Self-Potential (SP) in Colorado School of Mines (CSM) Intramural Field North has succeeded in showing the existence of shallow object as a metal pipe. The location is suspected to experience land subsidence caused by mining activities that results a seepage (water). Therefore, another interpretation is carried out from that data (secondary) related to the subsurface rocks layer. Based on the reprocessed data using RES2DINV and Surfer 13, the subsurface rocks layer that obtained is composed of silt-clay, sandstone, alluvium, clay, shale, and limestone with the range of apparent resistivity from 19.5 ?m to 240 ?m and the range of electric potential from - 15.3 mV to 5.3 mV. The presence of the aquifers is thought to be divided into two aquifers, the confined aquifer and the unconfined aquifer. The confined aquifer to be located at the depth of ± 3-6 m that consisting of alluvium with the water table is predicted at the depth of ± 3 m, while the unconfined aquifer to be located at the depth of ± 6.37-13 m that consisting of sandstone. Based on the result of SP data, the groundwater is predicted to flows from northeast to southwest. But, this result is not relevant to Darcy’s concept about groundwater flows. It occurs because the system of groundwater flow on the location is affected by the golden fault. That fault is a reverse fault with a moderate to steep dip to the west, including 35° - 50° to the southwest. Beside of that, it is affected by old mining activities that suspect to have changed the subsurface structure.