Seismic Activity in the Banda Sea: The November 2023 M7.1 Earthquake and Regional Tectonic Context

The Banda Sea region in eastern Indonesia represents one of the world's most seismically active zones, driven by the complex convergence of the Australian and Eurasian plates along the Banda Arc. This tectonic setting features subduction, collision, and strike-slip faulting, resulting in frequent moderate to great earthquakes. On 8 November 2023 at 04:53 UTC, a magnitude 7.1 earthquake struck the Banda Sea at a shallow depth of 6.0 km. The event occurred amid a documented sequence of strong shocks in the area since 2000. The Banda Arc's geology stems from the northward subduction of the Australian plate beneath the Eurasian plate, creating a curved trench system with associated volcanic islands. Shallow crustal earthquakes like the 2023 event often arise from thrust or normal faulting within the overriding plate or along the subduction interface. Historical data indicate recurrent large events, underscoring the region's high seismic hazard. Strong earthquakes since 2000 include:

• M 7.1 in the Banda Sea on 8 November 2023
• M 7.6 near Pulau Pulau Tanimbar, Indonesia, on 9 January 2023, located 87 km from the 2023 epicenter
• M 7.3 in the Banda Sea on 24 June 2019, 41 km distant
• M 7.1 in the Banda Sea on 10 December 2012, 33 km away
• M 7.1 in the Banda Sea on 2 March 2005, 44 km distant These events cluster within a limited epicentral area, reflecting persistent strain accumulation and release along local fault structures. Depths for recent shocks have remained predominantly shallow, increasing potential for strong ground shaking in nearby islands. The tectonic history of the Banda Sea encompasses multiple episodes of plate reorganization since the Miocene, leading to the current arcuate geometry. Volcanic activity accompanies seismicity, with several active volcanoes situated along the inner arc. Monitoring by regional networks continues to track aftershock sequences and deformation patterns following major events.

References

USGS Earthquake Catalog Global CMT Project Indonesian Meteorological, Climatological, and Geophysical Agency (BMKG) reports