Indonesia, M7.5 Earthquake in Maluku

OVERVIEW:

At 0047 HRS UTC+7 of 10 January 2023, a M7.9 tectonic earthquake, corrected to M7.5 with epicentre at 7.37S, 130.23E and a depth of 130km (located 136 km Northeast of Maluku Tenggara Barat) rocked Maluku, Indonesia (BMKG).
Considering the location of the epicentre and the depth of the hypocentre, the earthquake is a result of subduction activity in Banda Sea. Analysis of Indonesia’s Badan Meteorologi, Klimatologi dan Geofisika (BMKG) shows that the earthquake have a thrust fault mechanism.
Further, according to BMKG, the shock of this earthquake was felt in Saumlaki Town (Taninbar Islands Regency) MMI V (felt by almost all residents, waking up many people); Dobo Town (Aru Islands Regency) and Tiakur Town(Southwest Maluku Regency) MMI IV (crowds can feel the earthquake from indoors and outdoors. Some pottery could break, windows and doors rattle, and walls produce sound); and Sorong City, Kaimana, Alor, Waingapu, Waijelu, and Lembata Regencies MMI III-IV (many people felt it in the house during the day).


PRELIMINARY ANALYSIS: This is a very strong earthquake. Based on the preliminary data, earthquakes of this depth and magnitude are expected to result in moderate to severe shaking within 95.0 km from the epicenter. It is estimated that 121,540 people, 30,385 households, and $779 Million (USD) of infrastructure (total replacement value) are concentrated within this radius.



ANALYSIS: Modeling results show that this earthquake DOES have a TSUNAMI POTENTIAL. At 0343 HRS UTC+7, TSUNAMI WARNING HAS BEEN ENDED by BMKG. Pacific Tsunami Warning Center (PTWC) further assessed this earthquake and mentioned that there is NO TSUNAMI THREAT. However, strong currents and dangerous sea level fluctuations are still possible.



AFTERSHOCKS: BMKG monitoring results show that there are FOUR (4) aftershocks as of 0400 HRS UTC+7, with a maximum magnitude of M5.1 and minimum magnitude of M4.1.



IMPACTS AND DAMAGES:

According to Badan Nasional Penanggulangan Bencana (BNPB), the earthquake is felt strongly in Southwest and Southeast Maluku, Ambon City, Tanibar Islands, Tual City, and Western Seram Regency.
According to the report from the BNPB, as of 10 Jan at 1030 HRS UTC+7, this earthquake have caused 1 person injured and 44 households affected. Reports of damages includes 33 houses (19 slightly, 3 moderately, 11 heavily) and 4 schools.



PREPAREDNESS AND RESPONSE:

Local Disaster Management Authority (BPBD) in Southwest and Southeast Maluku, Ambon City, Tanibar Islands, Tual City, and Western Seram Regency continue to coordinate with relevant agencies and conducts monitoring. Impact and damage assessments are ongoing by relevant authorities.
BMKG advised people on the coast of the affected cities / regencies are advised to do normal activity as well as advised communities in all affected areas to remain calm and ensure the building condition before entering the building.


The AHA Centre will continue to monitor for further developments and issue necessary updates.