Very strong M7.3 earthquake hits Barat Daya Islands at intermediate depth, Indonesia

A major earthquake registered by the USGS as M7.3 hit Barat Daya Islands, Maluku, Indonesia at 18:25 UTC on December 29, 2021. The agency is reporting a depth of 166 km (102 miles). EMSC is reporting M7.3 at a depth of 170 km (105 miles). BMKG is reporting M7.4 at a depth of 210 km (130 miles).

The epicenter was located about 122 km (76 miles) NNE of Lospalos and 158 km (98 miles) NE of Baukau, Timor Leste.

There are about 80 000 people living within 100 km (62 miles).

140 000 people are estimated to have felt strong shaking, 365 000 moderate, and 3 084 000 light.

The USGS issued a Green alert for shaking-related fatalities and economic losses. There is a low likelihood of casualties and damage.

Overall, the population in this region resides in structures that are vulnerable to earthquake shaking, though resistant structures exist. The predominant vulnerable building types are unreinforced brick with concrete floor and precast concrete frame with wall construction.

Recent earthquakes in this area have caused secondary hazards such as tsunamis and landslides that might have contributed to losses.

Image credit TW/SAM, Google

In an update released at 07:34 UTC on December 30, BMKG said it received no reports of casualties and damage.

This earthquake did not cause a tsunami even though the epicenter of the earthquake was located at sea, because it did not cause underwater deformation that could trigger a tsunami.

Previously, the Southwest Maluku Regency had experienced two destructive earthquakes – M5.6 on December 11, 2021, at a depth of 10 km (6.2 miles), and another M5.6 on December 16, 2021, at a depth of 26 km (16 miles). The two destructive earthquakes were caused by active fault movements.

Estimated population exposure to earthquake shaking

Selected cities exposed

Regional seismicity

Featured image credit: TW/SAM, Google