Refining the Regional Aftershocks Catalog of the Ambon Earthquake MW 6,5 on 26th September 2019 using manual picking and a non-linear algorithm: Preliminary Result
B Kamaruddin(a*,d), A D Nugraha(b), D P Sahara(b), and Y Halauwet(c,e)

a) Master Program of Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Bandung Institute of Technology
*basri.kamaruddin[at]students.itb.ac.id
b) Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Bandung Institute of Technology
c) Earth Sciences Graduate Program, Faculty of Earth Sciences and Technology, Bandung Institute of Technology
d) Agency for Meteorology, Climatology, and Geophysics (BMKG), Ternate, Indonesia
e) Agency for Meteorology, Climatology, and Geophysics (BMKG), Ambon, Indonesia

Abstract

A destructive earthquake with magnitude MW 6.5 occurred in Ambon, Indonesia, on 26th September 2019. This earthquake generated an aftershock sequence. In this study, we determined the location of the aftershocks sequence using a non-linear algorithm from the Non-Linear Location (NonLinLoc) program. The catalogue and waveform data were collected using 11 seismographs from BMKG regional network located around Maluku archipelago. The data was recorded between 26th September till 18th October 2019. We have manually picked the P-and-S wave phase by using Seisgram2K software. In our preliminary results, we have located about 1,300 events of aftershock sequence with about 8,500 phases of P and S waves. Overall, the location of the focus depth of the aftershocks sequence is dominantly distributed in between 5 - 25 km. Approximately ~70% of the distribution of aftershock locations show a North-South (N-S) oriented pattern from west Seram to Ambon Islands. Meanwhile, about ~20% of the aftershock^s locations are distributed around Ambon Island. Our ongoing and future study is to determine accurate hypocentre location derived from double-difference hypocenter relocation with waveform cross-correlation.

Keywords: Ambon earthquake 2019- Repicking P & S- Non-linear algorithm- Hypocenter location- Waveform cross-correlation

Topic: Earth and Planetary Sciences