Analysis of the Mw 6.5 Ambon Earthquake (September 26, 2019) based on the aftershocks hypocenter relocation

Abstract

On September 26, 2019, an earthquake (Mw 6.5) occurred in the northern part of Ambon Island, Molucca, East Indonesia. The National Authority show this earthquake caused infrastructures damage and 28 fatalities. Up to October 31, 2019, the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG) seismic network had recorded 479 aftershock events. We have relocated 463 out of the 479 aftershocks using the double-difference method. Our results show that some improvements in the hypocenter locations, where the focal depths of initial earthquakes fixed at 10 km have been updated to ∼9.8 km depth on average. There are two aftershock clusters in a North-South direction of ∼35 km length between Ambon Island and Haruku Island and in a West-East direction of ∼30 km length in the Ambon Island, each with a width of ∼8 km.