GEOELECTRICAL METHODS FOR GEOTHERMAL EXPLORATION IN ENDUT GEOTHERMAL PROSPECT AREA, BANTEN PROVINCE, INDONESIA

Abstract

Gunung Endut, which is located in Banten Province, Indonesia, holds considerable geothermal
energy potential. Besides the existence of the Cikawah (CKW) and Handeuleum (HDL) hot springs, alteration
mineral revealed on the surface as a result of contact with heat source are scattered in a relatively wide area to
the west of the peak of the volcanic mountain. A geoelectrical method is an essential tool for mapping low
resistivity distributions that infers the distribution of mineral alteration. Such an investigation had been
conducted in 2006, however, the interpretation of the DC resistivity method was only based on its apparent
results which could not precisely image the actual subsurface situation. In this study, we perform audiomagnetotelluric (AMT) technique to obtain resistivity variations at deeper depths. Based on the interpretation
results of all the geoelectrical methods, the distribution of impermeable zone with low resistivity is detected in
the eastern part of the study area, approximately 3 km to the west of Gunung Endut’s peak and 2 km east of
the CKW hot spring. The discovery of alteration minerals in these regions supports the interpretation results.
The existence of this strong alteration is likely to be controlled by a trending NW-SE fault structure, estimated
from the striking analysis and is augmented with both geochemistry analysis and relative gravity study carried
out previously. These facts lead to the conclusion that the existence of a geothermal reservoir is estimated
between the manifestations of the CKW hot spring and peak of Gunung Endut.