2015 Illapel earthquake explained

2015 Illapel earthquake
Timestamp:2015-09-16 22:54:32
Anss-Url:us20003k7a
Isc-Event:611531714
Local-Time:19:54:32 CST (UTC-3)
Duration:2 minutes
Magnitude:8.3–8.4 Mw
Depth:22.4 km (USGS)
Location:-31.57°N -71.654°W
Affected:Chile
Argentina[1]
Tsunami:Yes (4.5 m or 15 ft)
Aftershocks:31 of 6.0 Mw or higher, over 5,000 in total (as of June 2017)
Casualties:15 dead, 34 injured, 6 missing and 16,646 homeless in Chile
1 fatality and minor injuries in Argentina[2]

The 2015 Illapel earthquake occurred 46km (29miles) offshore from Illapel (Coquimbo region, Chile) on September 16 at 19:54:32 Chile Standard Time (22:54:32 UTC), with a moment magnitude of 8.3–8.4.[3] [4] [5] The initial quake lasted between three and five minutes;[6] it was followed by several aftershocks greater than magnitude six and two that exceeded 7.0 moment magnitude.[7] The Chilean government reported 15 deaths, 6 missing and thousands of people affected. In Buenos Aires, Argentina, a man died from a stroke while he was evacuating a building.[8]

Earthquake

The earthquake occurred on thrust faults along the boundary of the Nazca and South American plates. The region frequently produces large earthquakes, and 15 others of magnitude 7 or higher have taken place within 400 km of the epicenter over the past 100 years.[4] The last big quake that occurred in this region was the 1943 Ovalle earthquake, reaching a magnitude in the range 7.9–8.2; however, comparisons of the associated source time function (the time history of release of seismic moment) show that the 2015 event was significantly larger than the 1943 earthquake, in terms of duration, up-dip rupture extent and tsunami size.[9]

This earthquake had an unusual foreshock, just 20 seconds before the main 8.3 earthquake, reaching a magnitude of 7.2. This has been considered as one of the most complex earthquakes to be ever studied in Chile.

Damage and range

Illapel, an inland city of 30,000 residents, was reported immediately to be without electricity or drinking water.[10] Many towns and small cities in the Coquimbo region saw a lot of damage, where the earthquake was felt with an intensity of VIII Mercalli. The panic took over the great cities like La Serena, Valparaiso and the capital Santiago. Two days after the quake, about 90,000 people were still without electricity.[11] On September 21, officials were reporting over 9,000 people had been left homeless by the quake.[12]

Tall buildings swayed and car alarms were set off in Buenos Aires, away,[13] and the earthquake was felt in São Paulo, more than away.[14] The Argentine provinces of Mendoza, San Juan, Córdoba, Tucumán, La Rioja, San Luis and Santa Fe were also affected.[15]

Tsunami

Tsunami watches, warnings, and advisories were issued in Ecuador, Peru, New Zealand, Fiji, Solomon Islands, Hawaii, California and Japan.[16] The first tsunami waves arrived on the Chilean coast within minutes.[17] A series of waves reaching at least 4.5m (14.8feet) high were observed along the coast of Coquimbo and the cities of Coquimbo, Tongoy and Concón nearby to Valparaiso reported flooding; large fishing vessels were swept into the streets of Coquimbo, which reported heavy damage. The port of Coquimbo, along with the Costanera, was heavily damaged.[18] The tsunami also damaged the iconic La Serena monumental lighthouse.

In the coastal city of Tongoy, large areas along the sea front were destroyed, along with the Tongoy beach itself, which was heavily affected by both earthquake and tsunami. Across the region at least 500 buildings were destroyed, while dozens of beachfront homes in Los Vilos were damaged or destroyed. A state of emergency was declared in Coquimbo a day after the tsunami, with troops to be deployed to the area.

Evacuations

Chilean authorities ordered the immediate evacuation of the coast due to tsunami risk,[19] with many people in coastal areas receiving automatic notices by cellphone shortly after the quake.[6] The undersecretary for the ministry of the interior and public security reported that the evacuation affected one million people across the country.[20]

Although causing significant damage, the Illapel earthquake's low death toll relative to the 525 casualties of the significantly more powerful 2010 Chile earthquake was credited, in part, to its occurrence in a less populated region, better coastal preparedness and an improved tsunami warning system, the longstanding enforcement of seismic building codes, and an improved emergency response.[21]

See also

Notes and References

  1. News: Tsunami warnings from California to New Zealand after 8.3 quake hits Chile . The Telegraph . Akkoc . Raziye . Alexander . Harriet . September 17, 2015 .
  2. Web site: Gobierno confirma que cifra de fallecidos por terremoto aumenta a 10. Ahora Noticias. September 17, 2015. September 17, 2015. Spanish. Government confirms that the number of deceased people by the earthquake increases to 10. August 6, 2016. https://web.archive.org/web/20160806051047/http://www.ahoranoticias.cl/chile/santiago/153575-gobierno-confirma-que-cifra-de-fallecidos-por-terremoto-aumenta-a-10.html. dead.
  3. Web site: Sismos Importantes y/o Destructivos (1570 a la fecha). Centro Sismológico Nacional. 6 December 2022.
  4. Web site: M 8.3 - 48km W of Illapel, Chile. United States Geological Survey. September 16, 2015.
  5. "Strong quake shakes Chile capital, causing buildings to sway", Associated Press, September 16, 2015. Accessed September 16, 2015
  6. News: Chile confronts major quake with fortified buildings, alerts . September 17, 2015 . September 17, 2015 . Associated Press . Luis Andres . Henao . Eva . Vergara . dead . https://web.archive.org/web/20150923062423/http://m.wsbradio.com/ap/ap/international/big-quake-rattles-north-chile-sets-off-small-tsuna/nngrp/ . September 23, 2015 .
  8. News: Onemi: aumentan a 13 los muertos y a seis los desaparecidos . es . September 18, 2015 . September 19, 2015 . . October 7, 2015 . https://web.archive.org/web/20151007204425/http://www.latercera.com/noticia/nacional/2015/09/680-647858-9-onemi-aumentan-a-13-los-muertos-y-a-seis-los-desaparecidos.shtml . dead .
  9. Tilmann. F. . Zhang. Y. . Moreno. M. . Saul. J. . Eckelmann . F. . Palo . M. . Babeyko. A. . Chen. K. . Baez. J.C.. Schurr. B.. Wang. R.. Dahm. T. . 2015 . The 2015 Illapel earthquake, central Chile: A type case for a characteristic earthquake? . Geophysical Research Letters . 43 . 2 . 574–583 . 10.1002/2015GL066963. free .
  10. News: Tsunami warning after powerful earthquake hits Chile. September 17, 2015. September 17, 2015. Collie Mail.
  11. Web site: Chile quake: State of emergency declared for Coquimbo . BBC News Online . September 17, 2015 . September 18, 2015.
  12. News: Thousands left homeless by Chile quake. September 21, 2015. SkyNews.
  13. News: Strong Chile earthquake sets off tsunami waves – BBC News. September 17, 2015. BBC News.
  14. Web site: Illapel to São Paulo: 2620 km. Wolfram Alpha . September 17, 2015.
  15. Web site: El sismo se sintió con fuerza en distintas provincias: los vecinos se autoevacuaron. The earthquake was strongly felt in several provinces: the neighbors self-evacuated. Spanish. Gabriela Origlia. Pablo Mannino. amp. September 16, 2015. La Nación . September 16, 2015.
  16. Web site: 〔チリ中部沖M8.3〕津波注意報発表中 太平洋沿岸で最大0.8mの津波観測(18日13時30分現在)（レスキューナウニュース） - Yahoo!ニュース . September 18, 2015 . dead . https://web.archive.org/web/20150921062842/http://headlines.yahoo.co.jp/hl?a=20150918-00000006-rescuenow-soci . September 21, 2015 .
  17. News: Eric. Holthaus. September 17, 2015. September 18, 2015. Slate. Small Tsunami Reaches Hawaii and California, Widespread Damage Reported in Chile.
  18. News: Chileans pick through debris after powerful quake; 10 dead. Reuters. Felipe. Iturrieta. September 17, 2015 . September 17, 2015.
  19. News: Chile Earthquake Strikes Coast, Forcing Residents to Evacuate . The New York Times . September 16, 2015 . September 17, 2015 . 0362-4331 . Pascale . Bonnefoy . Simon . Romero.
  20. Web site: Chile earthquake: massive 8.3 magnitude tremor strikes Santiago . The Guardian . September 17, 2015 . September 17, 2015 . Michael . Safi.
  21. News: Why Chile's Latest Big Earthquake Has a Smaller Death Toll . Pascale . Bonnefoy . Patrick J. . Lyons . The New York Times . September 17, 2015 . September 18, 2015.

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