ESTIMATION OF RAYLEIGH WAVE GROUP VELOCITY STRUCTURE IN CIANJUR EARTHQUAKE ZONE 2022 (M 5.6), WEST JAVA USING AMBIENT SEISMIC NOISE TOMOGRAPHY METHOD

• Main Author: Adelia Putri, Dwista
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/76775
• Institution: Institut Teknologi Bandung

The shallow earthquake with a magnitude of 5.6 that occurred in Cianjur, West Java on November 21, 2022, caused a lot of damage and casualties. The earthquake was located north of the Cimandiri Fault in the Rajamandala segment and was followed by many aftershocks located to the northeast relative to the mainshock. This earthquake was triggered by a nearby fault and the underlying rock structure, so a study of the subsurface structural profile is needed. One of geophysical method that can be applied to image the subsurface profile is ambient seismic noise tomography. This study utilizes Rayleigh waves, which are surface waves that are easily extracted from the results of cross-correlation in vertical components. The data used are the recording results of 19 seismometers installed by ITB around the earthquake source zone from November 28 to December 21, 2022. The inversion results of the Rayleigh wave group velocity map for the period of 2.0 s - 6.0 s that have been obtained show a low-velocity contrast that has a soft rock structure at low to medium periods and a high-velocity contrast that has a hard rock structure at medium to high periods in the mainshock area and its surrounding