June 28, 2024 Earthquake: Arequipa, Peru

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Tectonic Summary

The June 28, 2024, M 7.2 earthquake offshore southern Peru occurred as the result of shallow thrust faulting on or near the boundary between the South America plate and the subducting Nazca plate. The Nazca plate subducts beneath the South America plate at the Peru-Chile Trench offshore of western South America, 90 km to the southwest of today’s earthquake, and dips east-northeast beneath the South American continent. At the location of the June 28, 2024 earthquake, the Nazca plate moves to the east-northeast with respect to the South America plate at a velocity of about 70 mm/yr. The location, depth and focal mechanism solution of today’s earthquake are consistent with it occurring on the megathrust interface between the two plates.

While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Thrust-faulting events of the size of the June 28, 2024 earthquake are typically about 55x30 km (length x width).

The plate boundary region between the Nazca and South America plates experiences many earthquakes. The region within 250 km of the epicenter of the June 28, 2024 earthquake has experienced 15 previous earthquakes of M 6.5 and larger over the preceding century. The largest of these, the M 8.4 earthquake of June 23, 2001, occurred along the plate boundary 95 km to the southeast (and ruptured from there ~ 200 km to the southeast). It resulted in at least 74 fatalities and destroyed more than 17,000 homes. More recently in January 2018 a M 7.1 earthquake struck about 30 km to the northwest of the June 28th earthquake. The 2018 quake killed two people and caused power outages and landslides that blocked roads in Acari, Atico and Caraveli.

At least 30 people injured; 11 homes destroyed; 3,000 homes, 11 public buildings, and 2 bridges damaged; power outages occurred and landslides blocked roads in Arequipa. Twelve people injured and 10 homes destroyed in Ica. Some homes destroyed, 11 public buildings damaged and rockfalls occurred in Ayacucho and one building damaged in Lima. A tsunami with a wave height of 20 cm was recorded at Chala.

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In the final report, the Civil Defense officials of the affected districts updated the figures with the following data: 14 people injured: five in Yauca, one in Atiquipa and 8 in Acari.; 05 people affected: three in Cahuacho and two in Bella Union.; 14 houses affected: six in Yauca, three in Cahuacho, three in Acari and two in Bella Union.; 02 bridges affected: one in Chala and another in Huanuhuanu.; 06 educational institutions affected: two in Yauca, two in Jaqui and two in Bella Union. Drinking water supply network affected by 20% in Jaqui.; Electrical service network affected in Atiquipa and Lomas. 0.4 kilometers of roads affected in Caraveli, Chaparra, Huanuhuanu, Jaqui and Acari.