Source Mechanism Analysis of Aftershocks of the Mw 5.6 Cianjur, West Java Earthquakes Using Local Seismographic Networks
Muhammad Fikri Azhari (a*), Andri Dian Nugraha (b), Zulfakriza (b), Aditya Lesmana (b)

a) Faculty of Earth Sciences and Technology, Bandung Institute of Technology
Jalan Ganesha 10, Bandung 40132, Indonesia
*fikriazharimuhammad[at]gmail.com
b) Faculty of Mining and Petroleum Engineering, Bandung Institute of Technology

Abstract

On November 21, 2022, a significant earthquake shook the Cianjur area, West Java causing severe damage to the area. In this study we analyzed the seismicity by magnitude and hypocenter of the 2022 Cianjur Earthquakes. Twenty stations were deployed to monitor aftershocks from 22 November to December 2022. We determined earthquake locations through re-picking of the P- and S-waves arrival times recorded by the local network. The aftershock hypocenters were determined using a nonlinear approach and relocated using double-difference method. We also conducted focal mechanism analysis to estimate the type of fault slip. The results indicate improved hypocenter locations, where patterns of seismicity in Cianjur, West Java were delineated clearly. There were more than 400 aftershocks with the largest magnitude Mw 4.2 and the smallest Mw 1.2. Based on the results of the focal mechanism model, this earthquakes caused by a right strike slip mechanism. This earthquake cluster is outside the Cimandiri fault zone, there is a possibility that the source of the earthquakes was caused by a fault that has not been identified.

Keywords: Cianjur Earthquakes- Local Seismographic Networks- Source Mechanism.

Topic: Solid Earth Sciences