March 31, 2022 Earthquake: Loyalty Islands, New Caledonia

Reference #13456:

Vila, Shefa, Vanuatu - CDI: 5; Tadine, Iles, New Caledonia - CDI: 5; Noumea, Sud, New Caledonia - CDI: 4; Bouloupari, Sud, New Caledonia - CDI: 3

Tectonic Summary

The March 31, 2022, M 7.0 earthquake occurred as the result of low angle thrust faulting on or near the plate boundary interface between the Australia and Pacific plates. Focal mechanism solutions indicate the earthquake occurred on either a shallow dipping fault striking to the northwest or on a steeply dipping fault striking to the southeast. The earthquake was preceded by an M6.9 foreshock about 8 hours earlier. At the location of this earthquake, the Australia plate converges with the Pacific at a rate of approximately 73 mm/yr. At the South New Hebrides Trench, Australia lithosphere sinks beneath the Pacific plate, descending into the mantle and forming the New Hebrides/Vanuatu subduction zone, stretching from New Caledonia in the south to the Santa Cruz Islands in the north.

While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Earthquakes of this size are typically about 40x20 km (length x width).

The Loyalty Islands region is very active seismically, and the region within 250 km of the March 31, 2022, earthquake has hosted 19 other M 7+ earthquakes over the preceding century. The largest prior events were an M7.7 on February 10, 2021, and an M 7.7 earthquake on May 16, 1995. Because of their remote locations, earthquakes in this region as less likely to create strong shaking in populated areas.