M 7.4 Earthquake – 12 km SSW of Santa María Zapotitlán, Mexico

2020-06-23 15:29:05 (UTC) | 16.029°N 95.901°W | 26.3 km depth

Tectonic Summary

The June 23, 2020, M 7.4 earthquake near Oaxaca, Mexico occurred as the result of reverse faulting on or near the plate boundary between the Cocos and North American plates. Focal mechanism solutions for the event indicate rupture occurred on either a shallowly dipping thrust fault striking towards the west or on a steeply dipping reverse fault striking towards the ESE. The depth and focal mechanism solutions of the event are consistent with its occurrence on the subduction zone interface between these plates, approximately 100 km northeast of the Middle America Trench, where the Cocos plate begins its descent into the mantle beneath Mexico. In the region of this earthquake, the Cocos plate moves approximately northeastward at a rate of 60 mm/yr.

While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Reverse faulting events of the size of the June 23, 2020 earthquake are typically about 70 x 35 km in size (length x width).

Source: M 7.4 – 12 km SSW of Santa María Zapotitlán, Mexico