RELOKASI HIPOSENTER GEMPABUMI DONGGALA TAHUN 2018 MENGGUNAKAN METODE HYPORELOCATE
Keywords:
Hiposenter Gempabumi Donggala, Relokasi hiposenter, HyperelocateAbstract
On Friday, September 28th, 2018 at 17.02.44 WIB, a large earthquake that has the potential to cause a tsunami occurs in the Donggala area. BMKG release the earthquake parameters with magnitude 7.7, location 0.18 LS and 119.85BT or 26 km from the North Donggala Central Sulawesi. An earthquake that has depth 10 km was clarified as a strike-slip fault mechanism due to the Palu-Koro fault activity and followed by hundreds of aftershocks. The Palu-Koro fault crossing from the Makassar Strait to the northern coast of Bone Bay cuts the heart of Palu city to the Lariang River, Donggala. This study will relocate Donggala earthquake both foreshock, mainshock, and aftershock using the Hyporelocate method. This relocation uses the absolute travel time of 599 earthquakes, the relative travel time of 2492 earthquake pairs and 11-time coda cross-correlogram which are inverted with simulated annealing. This method has the advantage by reducing reliance on relocation results in absolute catalog locations by combing absolute travel time, restricting the relative distance between earthquakes based on the differential travel time of earthquake pairs, and of inter-earthquake distance correction based on stacking coda cross-correlogram. The results of relocation show that earthquake epicenter was more collected or focused than the initial position and formed a cluster in the form of a field with an area of about 250 km × 85 km. Most of the epicenter after being relocated shifted with a distance of 15‒20 km and the change in the depth of the dominant earthquake was less than 10 km. The direction of shifting the epicenter is spread evenly at random but the west is less dominant. Relocation using hypoRelocate showed a good improvement in quality with a decrease in total residual values after relocation results of the validation of hypoRelocate relocation with maps of ALOS-2 mode ScanSAR and ALOS-2 PALSAR-2 satellite images show that the results of the relocation are in the plane of the fault moving due to the main earthquake.
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