R.M. Sipayung1 , D. Sianipar2 , S. Prayoedhie2 , D. Daryono2
1National Seismological Center, Meterological and Geophysical Agency
2Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG), National Seismological Center, Jakarta, Indonesia
Abstract:
In early November 2018, an earthquake swarm took place in the Mamasa Region, West Sulawesi and resulted in moderate damage in the villages. BMKG reported more than 600 events within the first month with four of them having magnitude Mw > 5.0. The seismicity was accurately relocated by using double difference with cross-correlation data. A template matching technique was also utilized to provide catalog completeness for lower magnitudes. We show that the earthquakes concentrated on a 12-km length intensive plane and distributed irregularly along very shallow to about 15 km depth. This relocated seismicity suggests a ~90 km fault plane generated by the strike-slip fault. We propose it confidently as the source parameters of 29 earthquake (Mw > 4.0) using moment tensor inversions exhibit a dominant strike-slip mechanism trending NNE-SSW (average strike = ~200, average dip = ~80). Both our relocation and template matching techniques provided 4,170 events starting from 31 Oct – 27 Nov 2018 and from the westernmost part, moving gradually and diffusely to the east during early November 2018; eventually slowly decaying with time lasting for months. Our findings suggest the invaluable chance to elucidate the presence of active fault zone in this region.
