2015 Illapel earthquake

The 2015 Illapel earthquake occurred 46 km (29 mi) 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.[5][1][6] The initial quake lasted between three and five minutes;[7] it was followed by several aftershocks greater than magnitude six and two that exceeded 7.0 moment magnitude.[8] 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.[3][4][9]

2015 Illapel earthquake
USGS ShakeMap of the earthquake
UTC time2015-09-16 22:54:32
ISC event611531714
USGS-ANSSComCat
Local dateSeptember 16, 2015 (2015-09-16)
Local time19:54 CST (UTC-3)
Duration2 minutes[1]
Magnitude8.3–8.4 Mw[1]
Depth22.4 km (USGS)[1]
Epicenter31.570°S 71.654°W / -31.570; -71.654 (earthquake)[1]
Areas affectedChile
Argentina[2]
Max. intensityIX (Violent)[1]
TsunamiYes (4.5 m or 15 ft)
Aftershocks31 of 6.0 Mw or higher, over 5,000 in total (as of June 2017)
Casualties15 dead, 34 injured, 6 missing and 16,646 homeless in Chile[1]
1 fatality and minor injuries in Argentina[3][4]

Earthquake
The process of subduction of the Nazca plate under the South American plate.

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.[1] 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.[10]

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.[11] 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.[12] On September 21, officials were reporting over 9,000 people had been left homeless by the quake.[13]

Tall buildings swayed and car alarms were set off in Buenos Aires, 1,110 kilometres (690 mi) away,[3][14] and the earthquake was felt in São Paulo,[15] more than 2,600 kilometres (1,600 mi) away.[16] The Argentine provinces of Mendoza, San Juan, Córdoba, Tucumán, La Rioja, San Luis and Santa Fe were also affected.[17]

Tsunami

Tsunami watches, warnings, and advisories were issued in Ecuador, Peru, New Zealand, Fiji, Solomon Islands, Hawaii, California and Japan.[18] The first tsunami waves arrived on the Chilean coast within minutes.[19] A series of waves reaching at least 4.5 m (15 ft) high were observed along the coast of Coquimbo and the cities of Coquimbo, Tongoy and Concón nearby to Valparaiso reported flooding;[3] 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.[20] 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,[12] while dozens of beachfront homes in Los Vilos were damaged or destroyed.[20] A state of emergency was declared in Coquimbo a day after the tsunami, with troops to be deployed to the area.[12]

Evacuations

Chilean authorities ordered the immediate evacuation of the coast due to tsunami risk,[15] with many people in coastal areas receiving automatic notices by cellphone shortly after the quake.[7] The undersecretary for the ministry of the interior and public security reported that the evacuation affected one million people across the country.[3]

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]

Damage in Coquimbo
  • Ships on land
    Boats stranded in Coquimbo after the tsunami
  • Damaged and collapsed buildings
    Street scene near the coast in Coquimbo in the quake and tsunami aftermath.
  • Interior of library with scattered books
    Coquimbo municipal library, after the tsunami

See also

References
  1. "M 8.3 - 48km W of Illapel, Chile". United States Geological Survey. Retrieved September 16, 2015.
  2. Akkoc, Raziye; Alexander, Harriet (September 17, 2015). "Tsunami warnings from California to New Zealand after 8.3 quake hits Chile". The Telegraph.
  3. Safi, Michael (September 17, 2015). "Chile earthquake: massive 8.3 magnitude tremor strikes Santiago". The Guardian. Retrieved September 17, 2015.
  4. "Gobierno confirma que cifra de fallecidos por terremoto aumenta a 10" [Government confirms that the number of deceased people by the earthquake increases to 10] (in Spanish). Ahora Noticias. September 17, 2015. Archived from the original on August 6, 2016. Retrieved September 17, 2015.
  5. "Sismos Importantes y/o Destructivos (1570 a la fecha)". Centro Sismológico Nacional. Retrieved 6 December 2022.
  6. "Strong quake shakes Chile capital, causing buildings to sway", Associated Press, September 16, 2015. Accessed September 16, 2015
  7. Henao, Luis Andres; Vergara, Eva (September 17, 2015). "Chile confronts major quake with fortified buildings, alerts". Associated Press. Archived from the original on September 23, 2015. Retrieved September 17, 2015.
  9. "Onemi: aumentan a 13 los muertos y a seis los desaparecidos" (in Spanish). La Tercera. September 18, 2015. Archived from the original on October 7, 2015. Retrieved September 19, 2015.
  10. 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. doi:10.1002/2015GL066963.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. "Tsunami warning after powerful earthquake hits Chile". Collie Mail. September 17, 2015. Retrieved September 17, 2015.
  12. "Chile quake: State of emergency declared for Coquimbo". BBC News Online. September 17, 2015. Retrieved September 18, 2015.
  13. "Thousands left homeless by Chile quake". SkyNews. Retrieved September 21, 2015.
  14. "Strong Chile earthquake sets off tsunami waves – BBC News". BBC News. September 17, 2015.
  15. Bonnefoy, Pascale; Romero, Simon (September 16, 2015). "Chile Earthquake Strikes Coast, Forcing Residents to Evacuate". The New York Times. ISSN 0362-4331. Retrieved September 17, 2015.
  16. "Illapel to São Paulo: 2620 km". Wolfram Alpha. Retrieved September 17, 2015.
  17. Gabriela Origlia & Pablo Mannino (September 16, 2015). "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] (in Spanish). La Nación. Retrieved September 16, 2015.
  18. "〔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". Archived from the original on September 21, 2015. Retrieved September 18, 2015.
  19. Holthaus, Eric (September 17, 2015). "Small Tsunami Reaches Hawaii and California, Widespread Damage Reported in Chile". Slate. Retrieved September 18, 2015.
  20. Iturrieta, Felipe (September 17, 2015). "Chileans pick through debris after powerful quake; 10 dead". Reuters. Retrieved September 17, 2015.
  21. Bonnefoy, Pascale; Lyons, Patrick J. (September 17, 2015). "Why Chile's Latest Big Earthquake Has a Smaller Death Toll". The New York Times. Retrieved September 18, 2015.

Further reading
  • Easton, G.; González-Alfaro, J.; Villalobos, A.; Álvarez, G.; Melgar, D.; Ruiz, S.; Sepúlveda, B.; Escobar, M.; León, T.; Carlos Báez, J.; Izquierdo, T.; Forch, M.; Abad, M. (2022), "Complex Rupture of the 2015 Mw 8.3 Illapel Earthquake and Prehistoric Events in the Central Chile Tsunami Gap", Seismological Research Letters, 93 (3): 1479–1496, doi:10.1785/0220210283, ISSN 0895-0695, S2CID 247375743
  • Guo, Rumeng; Zheng, Yong; Xu, Jianqiao; Riaz, Muhammad Shahid (2019), "Transient Viscosity and Afterslip of the 2015 Mw 8.3 Illapel, Chile, Earthquake", Bulletin of the Seismological Society of America, 109 (6): 2567–2581, Bibcode:2019BuSSA.109.2567G, doi:10.1785/0120190114, S2CID 210625395
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