Microtremor array observation in Southern Part of the Bandung basin: deep 1d s-wave velocity structure

Abstract

Site amplification factor become crucial in seismic hazard microzonation, which depends on local geological condition, therefore identification of bedrock depth is very important related to sediment thickness. One of the Geophysical method that can be applied for subsurface investigation is microtremor array survey method (MAM). This method doesn’t require seismic source, so it is very possible to be applied in the urban area. Bandung basin is a research project for seismic hazard and risk study, where most of this area covered by high population and settlements that becomes the obstacle in this field survey. Geologically, Bandung basin consists of volcanic rock and floodplain, and we can find outcrop of Tertiary rock in some parts the basin. Seismicity in Bandung basin is very active because there are many seismic sources around it, such as shallow crustal and megathrust segment in the southern part. The microtremor array survey was conducted in Southern basin at 3 sites observation represent shallow and deep bedrock depth by using triangular array in shape. The result shows the bedrock depth in BB12 is 139 m, BB13 is 211 m and BB14 is 192 m. This condition represents the feature of bedrock position in Southern Bandung basin.