Analysis of Focal Mechanism Distribution in Northern Sulawesi

Abstract

Sulawesi has been known to have the complex condition of the geology and tectonics. It is indicated by natural phenomena such as volcanoes and earthquakes in Sulawesi. This study aimed to determine the latest tectonic order in Sulawesi based on the distribution focal mechanism. The locations of the study were in the Sulawesi 2º22’ N – 3º48’ S and 119º22’ – 124º22’. The earthquake data used were from BMKG since 2001 to 2015 with the criteria > M4.5. The strike, dip, and rake data were through Global-CMT for the earthquake in Sulawesi at the same time. An AB cross-section lies along the neck of Sulawesi which has strike-slip fault type of focal mechanism with a shallow depth allegedly caused by Palu Koro Fault activity. CD longitudinal section elongated in the eastern arm of Sulawesi to the ocean, which is dominated by the strike-slip fault showing the activity of Batui Fault at the shallow depths. Matano Fault activity was observed in EF cross-section dominated by a strike-slip fault on the land and at sea by a normal fault. This activity was observed at the shallow depths which shows Matano Fault activity. GH cross section was an event with depth with various subtypes of reverse fault which is relatively uniform turning into an indication of the Sulawesi Sea subduction activity.