Hypocenter Relocation of Local Earthquake using Double Difference Method in Central Sulawesi from BMKG Network Data: Time Periods of July 26 - August 18, 2021

Last July 2021, a destructive earthquake occurred in the northern Ampana area, Central Sulawesi, with the epicenter at sea. We investigated the earthquake and found 101 hypocenter points with a magnitude of 2-6 Mw from 26 July to 18 August 2021 using the BMKG network. Of the 101 earthquakes, we relocated the hypocenter using the multiple difference method and obtained 75 earthquake events resulting from the relocation. The results obtained from the relocation are that several earthquake events with a fixed depth of 10 km have been updated. To validate the results, we used a histogram of travel time results, which depict the relocation results as good, and some close to zero. The results of the hypocenter relocation have a depth of 5 to 30 km and are collected in one location. The shift's direction and angle from the relocation results show that most of them are in a dominant direction to the north. It is interpreted that the earthquake was caused by force activity caused by the Balantak thrust, which is in the east and has a north direction towards the study site.