IDENTIFICATION OF SOFT SOIL THICKNESS USING SHEAR WAVE (S-WAVE) REFLECTION SEISMIC METHOD IN INDRAMAYU AREA, WEST JAVA

Abstract

Indramayu Regency, West Java, geologically has the potential for land subsid-ence due to the dominance of Young Quaternary deposits as the main constituent rocks. To identify the geometry of geological structures and the physical charac-teristics of rocks at shallow depths, a subsurface survey was conducted using the shear-wave reflection seismic method. This survey employed a 48-channel Geode instrument with a vibroseis source (ELVIS III), with a 2-meter spacing be-tween source points and a 1-meter spacing between geophones. The processed data produced 24 seismic sections with a penetration depth of up to 60 meters. The shear wave velocity (Vs) values in the soft soil layer range from 50 to 200 m/s. Spatially, the thickness of the soft soil layer tends to increase toward the north and east of the study area, reaching a maximum thickness of 35 meters.