M 7.3 - 24 km WNW of Port-Vila, Vanuatu

Tectonic Summary

On December 17, 2024, a magnitude 7.3 earthquake occurred as the result of oblique normal faulting. The earthquake's depth places it beneath the boundary of the Australia and Pacific plates in the Coral Sea region, within the subducting Australia plate. Earthquakes that occur within a subducted plate, as opposed to at the interface of the plate, are termed intraslab earthquakes. In this region, the Australia plate moves east-northeast at approximately 85 mm/yr relative to the Pacific plate. The Australia plate descends eastward beneath the Pacific at the Vanuatu Trench.

The area where the Australia and Pacific plates meet is among the world’s most seismically active. In the century leading up to the December 17, 2024, earthquake, there were 24 earthquakes of magnitude 7 or larger within 250 km of this event. Most of these seismic events occurred along the plate boundary rather than as intraslab earthquakes within the subducted slab. Because of the different depths and locations within and around the subducted slab, earthquakes in this region can exhibit a range of faulting types that include reverse faulting, normal faulting, and oblique faulting. The largest recorded event in this region was a magnitude 7.9 earthquake approximately 86 km to the southwest in December 1950.