November 28, 2021 Earthquake: Amazonas, Peru

Ref #1053:

Tectonic Summary

The November 28th, 2021, M 7.5 northern Peru earthquake occurred as the result of normal faulting at an intermediate depth, approximately 110 km beneath the Earth's surface within the subducted lithosphere of the Nazca plate. Focal mechanism solutions indicate that rupture occurred on either a north-northwest or south-southeast striking, moderately dipping normal fault. At the location of the earthquake, the Nazca plate moves to the east relative to the South America plate at a velocity of about 70 mm/yr, subducting at the Peru-Chile Trench, to the west of the Peruvian coast and the November 28th earthquake. Earthquakes of northern Peru and most of western South America are due to strains generated by this ongoing subduction; at this latitude, the Nazca plate is seismically active to depths of about 650 km. This earthquake occurred in a segment of the subducted plate that has produced frequent earthquakes with focal depths of 100 to 150 km.

Earthquakes like this event, with focal depths between 70 and 300 km, are commonly termed “intermediate-depth” earthquakes. 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 large intermediate-depth earthquakes may be felt at great distance from their epicenters.

Large intermediate-depth earthquakes are reasonably common in this section of the Nazca slab, and five other intermediate-depth M 7+ events have occurred within 250 km of the November 28th earthquake over the past century. A M 7.5 earthquake on September 26th 2005, located at a similar depth but approximately 140 km to the south of the November 28th, 2021 earthquake, caused 5 deaths, about 70 injuries, and significant damage in the surrounding region. More recently, an M8.0 earthquake on May 26th 2019, approximately 230 km to the southeast of the November 28th 2021 earthquake, resulted in 2 deaths.

Ref #13089:

The people whose homes have been destroyed or uninhabitable totaled more than 13,200 this Tuesday, according to a report this Wednesday from the National Civil Defense Institute (INDECI). There are 223 houses destroyed, 772 uninhabitable and another 1,597 affected. In addition, a three-year-old boy from an indigenous community was crushed to death by falling wood. The landslides caused by the earthquake have caused the Utcubamba river to drain, which cut off the Fernando Belaunde highway, destroyed more than 100 houses and caused the death of livestock and poultry animals in two towns in the Amazon region. (Note: unofficial translation)

Ref #13090:

The strong earthquake destroyed highways in the Amazon and the roads that connect with other cities, leaving several areas isolated [...] The Ministry of Education indicated that 10 schools in Amazonas, two in Loreto and one in Piura have suffered damage to their infrastructure [...] earthquake left 17 injured and one minor died [...] around 45 health posts and centers that have been damaged, but only slightly. Two have suffered severe damage [...] 223 homes destroyed, 772 uninhabitable, and 1,597 affected. In addition to 65 affected schools and 42 affected health establishments. (Note: unofficial translation)

Ref #13238:

intensity VII in Santa Maria de Nieva. 3 injured, 488 houses destroyed, 1699 houses damaged. It was determined that the minor that died [ref #13089, 13090] was not due to earthquake.