AQUIFER IDENTIFICATION IN OPAK FAULT ZONE AFTER YOGYAKARTA EARTHQUAKE 2006 WITH SCHLUMBERGER CONFIGURATION GEOELECTRIC METHOD

Abstract

This research was aimed to determine resistivity values of aquifer constituent rocks, and to
determine aquifer characteristics and hydrostratigraphy in Opak fault zone. The location of research
was at Opak fault line Paten subvillage, with geographical coordinate of 7°55'18,39'' S to 7°57'09,72''
S and 110°19'22,26'' E to 110°22'56,06'' E. The method used was Schlumberger configuration
geoelectric method. Geoelectric method was one of the geophysics method which study earth
electricity based on the Ohm’s Law, by injecting a current through two current electrodes, the
potential different appeared from two potential electrodes can be measured. The data acquisition used
Naniura NRD 22S resistivitymeter. Number of sounding point were 3 points spaced by 10 meters and
measurement line length was 160 meters. Measurement results were analized using curve matching
method by IPI2win software determine subsurface layers based on resistivity. Results showed that
resistivity aquifer constituent rocks are about 19,3-300 Ωm which are sands, gravels, sandstones rock
types at 5-30 meters depth.
Keywords: Geoelectric Method, Aquifer, Paten Subvillage