RESISTIVITY AND REFRACTION SEISMIC MAPPING IN PRAMBANAN TEMPLE AREA

Abstract

Due to the Yogyakarta’s earthquake of 5.9 Richter scale in May 2006, the Prambanan temple (Siwa temple) has deformation up to 5 cm in the body stone, and some of the surface rocks in the upper, middle, and foot of the temple body are collapsed. The effect of the earthquake will influence the stability of the rock or soil in the subsurface. Thus, It is very importance to study the condition of the subsurface rock of the Prambanan site by geophysical method, i.e., geo-electric and seismic technique. The acquisitions of resistivity and seismic data are carried out in January 16-17, 2007. Five seismic and resistivity lines have been measured and the Hagiwara method has been applied to estimate the interface depth and velocity from the seismic data. The resistivity configuration system of in line position is dipole-dipole arrangement. The processing and the modeling use RES2DMOD and RES3DMOD. Two points are measured by vertical electrical sounding (VES) in Schlumberger configuration (between Siwa and Nandi temples) to know the resistivities distribution of soil vertically. The Progress 3.0 software was used for data processing. The results show that the bodies of temples are supported by hard rock velocity is 400-500 m/s and the resistivity is > 200 ohm-m, whereas the depth of the hard rock is (4-8) m from the surface. The thickness of the seal soil is about 8 m in the south area and 4 m in the north area. The low resistivity in front of the Siwa, Wisnu and Brahma temple at east side, was estimated as a drainage system of the Prambanan temple area. For more than 13 m depth finds water saturated sandstone.

Keywords: Prambanan Temple, VLF, Seismic