Abstract
The Mw 7.5 Palu earthquake that occurred in Palu-Central Sulawesi, Indonesia, on September 28, 2018, accompanied by the tsunami and liquefaction caused casualties and building damage in the city of Palu and its surroundings. One month later, a series of earthquakes swarm occurred in Mamasa, West Sulawesi. In this study, coulomb stress were calculated using a half-space elastic model in a square plane which is assumed to be homogeneous isotropy to analyze whether there is a relationship between earthquakes that occur in Palu and earthquakes swam in the coulomb stress field changes. The results show that the area that experienced a stress reduction predominantly towards the north and south of the mainshock hypocenter, while the aftershocks were at an increase in coulomb stress changes, so that the Mamasa earthquakes swarm probably have been triggered by the Palu earthquake.
Highlights
Abstrak: Gempabumi yang terjadi di Palu-Sulawesi Tengah, Indonesia, pada tanggal 28 September 2018 dengan magnitudo Mw. 7.5 yang disertai tsunami dan likuifaksi telah menyebabkan korban jiwa dan kerusakan bangunan di kota Palu dan sekitarnya
The results show that the area that experienced a stress reduction predominantly towards the north and south of the mainshock hypocenter, while the aftershocks were at an increase in coulomb stress changes, so that the Mamasa earthquakes swarm probably have been triggered by the Palu earthquake
New empirical relationships among magnitudo, rupture length, rupture width, rupture area, and surface displacement, Bulletin of the Seismological Society of America, v. 84, p. 974-1002
Summary
Berdasarkan katalog Badan Meteorologi Klimatologi dan Geofisika (BMKG), gempabumi Palu terjadi pada pukul. Rigiditas efektif dalam penelitian stress coseismic bervariasi antara 0.01 hingga 0.75, dengan nilai rata-rata μ = 0.4. Kalkulasi ∆CF F yang disebabkan oleh gempabumi bergantung kepada geometri dan distribusi slip, asumsi magnitudo, orientasi stress regional, dan nilai dari asumsi rigiditas. Sedangkan jika ∆CF F < 0 (bernilai negatif), artinya sesar pertama mendorong sesar kedua mengalami relaksasi sehingga peluang terjadinya failure semakin kecil, daerah ini sering disebut dengan daerah stress shadow. Garis hijau adalah Sesar Palu-Koro dan garis merah adalah sesar aktif lain di Sulawesi yang diperoleh dari Irsyam dkk. Gkan data parameter bidang sesar (strike = 348o, dip = 57o, danrake = −15o) diperoleh dari katalog Global CMT (Gambar 1) untuk menentukan panjang dan lebar sesar dengan menggunkan perhitungan Wells dan Coppersmith (1994).
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