March 18, 2023 Earthquake: Tumbes, Azuay, El Oro, Guayas, Peru, Ecuador

Reference #13456:

Tectonic Summary

The March 18th, 2023, M 6.8 southern Ecuador earthquake occurred as the result of oblique faulting at an intermediate depth, approximately 66 km beneath the Earth's surface near the subduction interface of the Nazca and South America plates. The faulting mechanism and depth suggest the event may have occurred within the subducted lithosphere of the Nazca plate. Focal mechanism solutions indicate that rupture occurred on either a near vertically dipping fault striking to the southeast or a moderately dipping fault striking to the southwest. At the location of the earthquake, the Nazca plate moves to the east relative to the South America plate at a velocity of about 73 mm/yr. Earthquakes in Ecuador and most of western South America are caused by the strains generated by ongoing subduction.

The depth of this earthquake places near the upper end of what are termed intermediate-depth earthquakes, with depths between 70 and 300 km. Intermediate-depth earthquakes represent deformation within subducted slabs rather than at the shallow plate interface between subducting and overriding tectonic plates. They typically cause less damage on the ground surface above their foci than is the case with similar-magnitude shallow-focus earthquakes, but they can still be destructive. Large intermediate-depth earthquakes may be felt at large distances from their epicenters.

Large earthquakes are common in this region of Ecuador. In the past century, 32 earthquakes M6.0 and larger have occurred within 250 km of this event. Significantly, on April 16, 2016, a magnitude 7.8 earthquake on the subduction zone interface ~350 km to the north resulted in over 700 deaths and over 27,000 injuries.

Reference #13486, #13488, #13708:

14 deaths (12 El Oro and 2 Azuay), 494 injured, 972 houses impacted, 291 houses destroyed, impacted infrastructure: 331 educational, 57 health facilities

Reference #1250:

15 deaths (14 Ecuador, 1 Peru); 495 injured (494 Ecuador; 1 Peru)