May 2, 2025 Earthquake: Drake Passage, Chile

Reference #13456:

Tectonic Summary

The May 2, 2025 magnitude 7.4 earthquake off the southern coast of Chile and Argentina occurred as the result of reverse faulting at shallow depth. The earthquake occurred on either a northeast or southwest dipping reverse fault beneath the Drake Passage, consistent with relative plate convergence motions in the region. The May 2 earthquake occurred in a region of complex tectonic interactions. Here, the South America, Antarctic, and Scotia plates meet at a single point, termed a triple junction. The Antarctic and South America plates form a predominantly convergent boundary, with Antarctica converging eastward at approximately 16 mm/yr relative to the South America plate. The Antarctica-Scotia plate boundary is predominantly a convergent boundary in the north, as evidenced by focal mechanism solutions in the region, and transitions to an oblique-convergent boundary further to the south. The South America-Scotia plate boundary trends east-west across the southern tip of the South American continent, forming a transform plate boundary.

While commonly plotted as points on maps, earthquakes of this magnitude are more appropriately described as slip over a larger fault area. Thrust faulting events of the size of the May 2, 2025, event are typically about 60 km by 35 km (length x width).

Since 1900, 12 other earthquakes of magnitude 6 or larger have occurred within 350 km of this earthquake, including three magnitude 7 and larger earthquakes. Magnitude 7.7 and 7.6 earthquakes occurred on the same day in 1949 along the east-west trending boundary between the Scotia and South America plates in southern Argentina. Additionally, a magnitude ~7.1 earthquake occurred in 1910 south of the May 2, 2025 earthquake along the boundary between the Antarctic and Scotia plates.