RELOCATION OF THE EARTHQUAKES SEQUENCE OF THE 26TH OF SEPTEMBER 2019 AMBON EARTHQUAKE MW 6,5 BASED ON WAVEFORM CROSS-CORRELATION ANALYSIS OF BMKG SEISMOGRAPH NETWORK (SEPTEMBER 18 TO OCTOBER 18, 2019)

• Main Author: Kamaruddin, Basri
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/63111
• Institution: Institut Teknologi Bandung

The earthquake relocation method is commonly used to improve the accuracy of earthquake location which could help us to understand the physical mechanism of earthquake. The aim of this research is to improve the accuracy of earthquake location and to understand the seismicity in Ambon Island and its surrounding area by relocating the 2019 Ambon earthquake sequence using the double-difference algorithm with waveform cross-correlation. The data that is used in this study came from earthquake data that recorded by 11 seismographs of the BMKG regional network located around Maluku archipelago. During the period from September 18 to October 18, 2019, 1377 earthquakes with total 8656 phases of P and S wave arrival times were successfully identified by manually repicked the arrival time of P and S waves. Then, by applying a non-linear algorithm, the initial hypocenter location of 1377 earthquakes could be determined. Waveform cross-correlation analysis had been used to all events waveform with correlation coefficient greater than equal 0.7. As a result, this study has succesfully relocated 716 out of 1377 earthquakes using the double-difference algorithm with waveform crosscorrelation data. This study found that the distribution of hipocenter location shapes three clusters, i.e one cluster in Ambon Island located near Ambon city with NW-SE oriented pattern and two clusters located in mainshock fault plane of Ambon earthquake 26 September 2019 MW 6,5 with N-S oriented pattern from Kairatu to Haruku Island. By analysing the result, it has been predicted that the NW-SE cluster in Ambon Island was a local fault which reactivated by stress transfer of mainshock of Ambon earthquake 26 September 2019. Further analysis of NW-SE cluster needs to be carried out for seismic hazard assessment considering it is located near to Ambon city, a crowded population urban area in Ambon Island.