BMKG: M 5.8 Mamuju Earthquake From Uncharted Shear Fault

JAKARTA - The Coordinator for Earthquake and Tsunami Mitigation of the Meteorology, Climatology and Geophysics Agency (BMKG) Daryono explained that the 5.8 magnitude earthquake that rocked Mamuju Regency, West Sulawesi (Sulbar) originated from an uncharted shear fault.

According to Daryono in a written statement received in Jakarta, Wednesday, the difference between today's Mamuju earthquake and the Mamuju Earthquake that occurred in January 2021 lies in the location of the epicenter and the mechanism of its source.

The epicenter of this earthquake is located at coordinates 2.77° South Latitude - 118.56° East Longitude, precisely at sea at a distance of 26 kilometers west of West Tapalang, Mamuju, West Sulawesi with a depth of 10 km.

"The mechanism of the earthquake this afternoon was a strike-slip fault, while in January 2021 the mechanism was a thrusting fault. The epicenter of today's earthquake is located at sea or offshore, while the epicenter of the January 2021 Mamuju Earthquake is located on land," Daryono said as quoted by Antara, Wednesday, June 8th.

Daryono said that today's Mamuju earthquake tends to be a type 2 earthquake, with characteristics of an opening earthquake (foreshocks) - a main earthquake (temporary main shocks) - aftershocks. Today's opening earthquake occurred yesterday, Tuesday 7 June 2022 at 16.21.41 WITA with a magnitude of 2.8.

The January 2021 Mamuju Earthquake also had an opening-Main-Aftershock type because it was preceded by an opening earthquake with a magnitude of 5.9 on January 14, 2021, at 14:35 WITA. Then, it was followed by a main earthquake with a magnitude of 6.2 on January 15, 2021, at 02.28 WITA. followed by a series of aftershocks.

The earthquake was felt very strongly in Mamuju and caused damage to a number of houses and other buildings.

This earthquake was also felt in Majene, Pinrang, Palopo, Palu, Sidrap, Pangkep, Makassar and Masamba. The Mamuju earthquake was also felt far away in Paser and Samarinda in Kalimantan.

"We should be grateful that the modeling results show that the Mamuju earthquake does not have the potential for a tsunami because in addition to the shear mechanism, the magnitude is not strong enough to cause deformations that can disrupt the seawater column," said Daryono.