January 14, 2021 Earthquake: Mamuju, Majene, Sulawesi, Indonesia

Ref #1053:

Tectonic Summary

The January 14, 2021, M 6.2 earthquake near Mamuju, Indonesia occurred as a result of reverse faulting at shallow depths on or near the boundary between the Sunda plate and Banda Sea microplate. Focal mechanism solutions for the earthquake indicate rupture occurred on either a shallowly dipping oblique reverse strike-slip fault striking towards the northwest or on a steeply dipping reverse fault striking towards the south, both of which indicate roughly east-west oriented compression. 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 January 14 earthquake, the Sunda plate moves east with respect to the Banda Sea microplate at a velocity of about 21 mm/year.

Shallow earthquakes of this size can often have a deadly impact on nearby communities. Historically, the island of Sulawesi in Indonesia where the January 14 earthquake occurred has hosted 119 earthquakes of M 6.0 or greater since 1900. The most recent prior significant earthquake was a M 7.5 strike-slip earthquake and associated tsunami in September 2018 that occurred ~300 km north of the January 14 event and led to severe impacts in the city of Palu and surrounding regions. The earthquake in 2018 contributed to approximately 4000 fatalities. The largest documented earthquake on the island of Sulawesi was a M 7.9 earthquake in January 1996. The 1996 earthquake – a shallow thrust faulting earthquake likely to have occurred on the regional subduction zone system at depth beneath the shallow crust - resulted in approximately 10 fatalities, over 60 injuries, and significant building damage in the local region. The January 14 M 6.2 earthquake was preceded by a M 5.7 earthquake 12 hours prior in the same location with a similar reverse faulting focal mechanism.

Ref #1250:

Deaths 110; Injured 826; Total damages USD 58.7 million

Ref #13727:

108 fatalities, 3369 injured, 92 USD million in economic losses

Ref #12829, 12830, 12831, 12832, 12838, 12839:

total number of victims who died in Mamuju and Majene Districts was 105, 3 missing victims, 19 survivors, 6,489 injured (mild to severe category) and 92,075 displaced.

[...]damaged at least 300 houses in Majene, BNPB said. Other buildings have also been badly damaged, including a military command office in Majene, and hotels and government buildings in Mamuju.

Nearly 10,000 people have been displaced in West Sulawesi, with over 1,150 houses destroyed as well as three hospitals.

Temporary data from BNPB as of January 26, 2021 recorded that the total damage and losses caused by the earthquake reached IDR 829.1 billion.

Damage data in Majene includes 4,122 houses, 32 units of economic and office facilities, 17 health facilities and 1 unit military office.

Damage data in Mamuju includes 3,741 houses, 5 health facilities, 3 units of bridges, 1 port, 1 mini market, 1 office building and 1 hotel.