Surface Wave Tomography Using Seismic Ambient Noise Data for Subsurface Imaging beneath Bandung Basin, West Java and Its Surrounding

Abstract

Seismic interferometry was applied to estimate the shear wave velocity structure beneath the Bandung Basin, West Java. The empirical Green’s function (EGFs) were obtained by cross-correlate each pairs of seismic stations from the temporary seismic network installed in the research area. In this research, we use Rayleigh wave dispersion data as the input for surface wave tomography. The obtained dispersion curves of Rayleigh waves are in the period range 1 - 12 s. The dispersion characteristics of EGFs was also analyzed to estimate the distribution of the ambient noise sources. Based on the symmetricity characteristics of the dispersive signals of EGFs from all two station pairs oriented relatively in N-S and W-E the seismic noise sources was originated from oceanic activity at the Coastline of Java Sea. Furthermore, the dispersion curves also show that the group velocities vary within range of 1.6–2 km/s. The inverted dispersion data into depth models provide the variation of shear velocity structures at depth 1–5 km in the range of 1–2.1 km/s. At depth 1–4 km, there appear high and low velocity contrast in the south of Mt. Tangkuban Perahu, which is may be related to the existence of Lembang Fault. Meanwhile, velocity models at depth 1–3 km show the lateral variation of shear wave’s velocity in the Bandung Basin. The high velocity structures within range 1.8–2.1 km/s lies in the Southwest toward Northeast in the middle of Bandung Basin. This structures divide Bandung Basin into two parts, Western part and Eastern part.