1784 Peru earthquake
  | |
| Local date | 13 May 1784 |
|---|---|
| Local time | 07:35 |
| Magnitude | Mw 8.4 |
| Epicenter | 16°30′S 72°00′W / 16.5°S 72.0°W |
| 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
[edit]Off the coasts of Peru and Chile, the Nazca plate subducts underneath the South American plate along the Peru-Chile Trench. At the location of the earthquake, the convergence rate between the two plates is 6.0 cm (2 in) per year. Large earthquakes at the plate boundary are relatively common, with similar large events occurring in 1687, 1784, 1868, and 2001. In the area of the earthquake, the Nazca Ridge functions as a semi-persistent rupture barrier. This inhibits the ability for most earthquakes to continue rupturing through this area. As a result, this earthquake cycle is considered to be bimodal, which means that the recurring earthquake is either a large (up to Mw 8.5) or a truly giant (Mw 9.0) earthquake. Only the 1604 and 1868 events are considered to have been the latter truly colossal events.[1][2][3][4]
Earthquake
[edit]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.[5] The seismic intensity distribution was similar to that of a Mw 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.[3]
Impact
[edit]Damage occurred from Caravelí to Arica; destruction also occurred in Sihuas, Vitor, Huchumayo, and Camaná.[5] In Arequipa, the earthquake killed at least 54 people and injured 500, while the total number of deaths did not exceed 500.[6] Many buildings and homes sustained heavy damage; of the 2,069 homes in the city, only 72 resisted the shaking.[5] 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.[7]
See also
[edit]
References
[edit]- ^ Villegas-Lanza, J. C.; Chlieh, M.; Cavalié, O.; Tavera, H.; Baby, P.; Chire-Chira, J.; Nocquet, J.-M. (24 September 2016). "Active tectonics of Peru: Heterogeneous interseismic coupling along the Nazca megathrust, rigid motion of the Peruvian Sliver, and Subandean shortening accommodation". J. Geophys. Res. Solid Earth. 121 (10): 7371–7394. Bibcode:2016JGRB..121.7371V. doi:10.1002/2016JB013080. S2CID 132735222. Retrieved 26 July 2022.
- ^ Okal, E.A.; Borrero, J.C.; Synolakis, C.E. (2006). "Evaluation of Tsunami Risk from Regional Earthquakes at Pisco, Peru". Bulletin of the Seismological Society of America. 96 (5): 1634–1648. Bibcode:2006BuSSA..96.1634O. doi:10.1785/0120050158.
- ^ a b 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.
- ^ Loveless, J. P.; Pritchard, M. E.; Kukowski, N. (22 November 2010). "Testing mechanisms of subduction zone segmentation and seismogenesis with slip distributions from recent Andean earthquakes". Tectonophysics. 495 (1–2): 15–33. Bibcode:2010Tectp.495...15L. doi:10.1016/j.tecto.2009.05.008. ISSN 0040-1951. Retrieved 9 July 2024.
- ^ a b c 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.
- ^ "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.
- ^ 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.