7.5 Earthquake Near Sulawesi Indonesia Triggers Tsunami (see video below) – On Friday, September 28, 2018, at 2:00 p.m. local time, a 7.5 earthquake with an epicenter located 78 kilometere north of Palu Indonesia triggered a tsunami. Dozens of aftersocks ranging from 5.8 to 4.7 continue to shake the region.
The tsunami swept away houses, with entire families families reported missing and a ship washed ashore. At least one person has been killed and numerous were reported injured. Indonesia sits on the Pacific Ring of Fire and is often hit by earthquakes.
The earthquake was caused by the Palu Karo thrust, which stretched from Palu to Teluk Bone.
The September 28, 2018, M 7.5 earthquake near Sulawesi, Indonesia occurred as a result of strike-slip faulting at shallow depths within the interior of the Molucca Sea microplate, part of the broader Sunda tectonic plate. Focal mechanism solutions for the earthquake indicate rupture occurred on either a left-lateral north-south striking fault, or along a right-lateral east-west striking fault. Eastern Indonesia is characterized by complex tectonics in which motions of numerous small microplates are accommodating large-scale convergence between the Australia, Sunda, Pacific, and Philippine Sea plates. At the location of the September 28th earthquake, the Sunda plate moves south with respect to Molucca Sea plate at a velocity of about 30 mm/year.
While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Strike-slip events of the size of the September 28, 2018 earthquake are typically about 120×20 km in size (length x width); modeling of this earthquake implies dimensions of ~80×30 km, predominantly down-dip and south of the hypocenter.
Direction data (below) indicate the position of the event relative to the place.
- Donggala, Indonesia 55.8 km (34.7 mi) NNE – Population: 0
- Palu, Indonesia 80.8 km (50.2 mi) N – Population: 282,431
- Poso, Indonesia 168.7 km (104.8 mi) NW – Population: 47,110
- Bontang, Indonesia 264.4 km (164.3 mi) E – Population: 101,691
- Mamuju, Indonesia 296.4 km (184.2 mi) NNE – Population: 15,000
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Video: 7.5 Earthquake Near Sulawesi Indonesia Triggers Tsunami