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1784 Peru earthquake

Local date	13 May 1784 (1784-05-13)
Local time	07:35
Magnitude	Mw 8.4
Epicenter	16°30′S 72°00′W / 16.5°S 72.0°W / -16.5; -72.0
Areas affected	Colonial Peru
Max. intensity	MMI X (Extreme)
Tsunami	Yes
Casualties	400

The 1784 Peru earthquake occurred at 07:35 local time on 13 May with a moment magnitude of 8.4 and maximum Mercalli intensity of X (Extreme). It affected southern Peru and generated a tsunami of 2–4 m (6 ft 7 in – 13 ft 1 in); the region was previously affected by magnitude 8.0 or greater earthquakes in 1604 and 1687.

Tectonic setting

Peru lies above the destructive boundary where the Nazca plate is being subducted beneath the South American plate along the line of the Peru–Chile Trench. The two plates are converging towards each other at a rate of about 78 mm (3.1 in) annually. Southwestern Peru has a history of very large earthquakes. The June 23 shock originated just southeast of the source of a magnitude 7.7 earthquake that occurred in 1996, and it appears to have involved rupture of part of the plate boundary segment that produced an earthquake of magnitude approximately 9.0 in 1868. The 1868 earthquake was destructive in towns that were heavily damaged in the June 23 earthquake. The 1868 earthquake produced a tsunami that killed thousands of people along the South American coast and also caused damage in Hawaii and the only recorded tsunami deaths in New Zealand.

Earthquake

The earthquake ruptured about 300 km (190 mi) of the subduction zone in southern Peru with an estimated moment magnitude of 8.4. The earthquake was smaller in magnitude with the events of 1604 and 1868. The seismic intensity distribution was similar to that of a M_w  8.4 earthquake in the same area on 23 June 2001, suggesting both earthquakes ruptured the same segment of the subduction zone with comparable rupture areas.

Impact

Damage occurred from Caravelí to Arica; destruction also occurred in Sihuas, Vitor, Huchumayo, and Camaná. In Arequipa, the earthquake killed at least 54 people and injured 500, while the total number of deaths did not exceed 500. Many buildings and homes sustained heavy damage; of the 2,069 homes in the city, only 72 resisted the shaking. Within 100 km (62 mi) of the city, many towns also experienced destruction. It was preceded by foreshocks at 02:00 and 05:00, and many aftershocks followed. The mainshock produced 4.5 to 5 minutes of shaking that occurred in a south to north direction, and three shocks were felt. The first phase, lasting 2 minutes, was a strong swaying motion; many people managed to escape from their buildings during this phase. The next phase, described as a swirling motion, lasted 1 minute, causing buildings to collapse and stones dislodged form the middle of walls. The final shock destroyed what buildings remained after the second phase.

See also

• Peru portal
• List of earthquakes in Peru
• List of historical earthquakes

References

1. ^ ANSS. "M 8.4 - 6 km SSW of Atico, Peru 2001". Comprehensive Catalog. U.S. Geological Survey.
2. Curtis L. Edwards, ed. (2002). Atico, Peru Mw8.4 Earthquake of June 23, 2001. Reston, VA: ASCE, TCLEE. ISBN 9780784406618. Archived from the original on 2013-04-14.
3. Morton, Jamie (13 August 2018). "NZ's only killer tsunami: What it means today". The New Zealand Herald. ISSN 1170-0777. Retrieved 2018-08-13.
4. ^ Dorbath, L.; Cisternas, A.; Dorbath, C. (1990). "Assessment of the size of large and great historical earthquakes in Peru" (PDF). Bulletin of the Seismological Society of America. 80 (3): 551–576. doi:10.1785/BSSA0800030551.
5. Giovanni, Melissa K.; Beck, Susan L.; Wagner, Lara (2002). "The June 23, 2001 Peru earthquake and the southern Peru subduction zone". Geophysical Research Letters. 29 (21): 14-1 – 14-4. doi:10.1029/2002GL015774.
6. "Significant Earthquake Information". National Geophysical Data Center / World Data Service (NGDC/WDS): NCEI/WDS Global Significant Earthquake Database. NOAA National Centers for Environmental Information. 1972. doi:10.7289/V5TD9V7K.
7. Ferro, Enrique Silgado (1978). Historia de los sismos mas notables ocurridos en el Perú (1513-1970): Geofísica Panamericana (PDF). Vol. 2. Boletín del Instituto de Geología y Minería. p. 32.