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1985 Rapel Lake earthquake
	Pichilemu
UTC time	1985-04-09 01:56:59
ISC event	527122
USGS-ANSS	ComCat
Local date	8 April 1985
Local time	21:56:59 UTC-4
Magnitude	7.2 Mw; 7.5 Ms
Depth	37.8 km (23 mi)
Epicenter	34°07′S 71°31′W / 34.12°S 71.51°W
Areas affected	Chile, Argentina
Max. intensity	MMI VI (Strong)
Tsunami	No
Casualties	2 killed

The 1985 Rapel Lake earthquake^[4]^[5] occurred on 8 April at 21:56:59 local time with a moment magnitude of 7.2 and a maximum perceived intensity of VI (Strong).^[6] The shock was centered 75 kilometres (47 mi) southwest of Santiago, Chile,^[3] with a focal depth of 37.8 km (23 mi).^[7]

Earthquake

The 9 April 1985 earthquake occurred in the same fault area as the 2010 Pichilemu earthquakes, and is considered by University of Chile Seismological Service a thrust fault-type interplate earthquake.^[8]

The earthquake, measured in the Modified Mercalli intensity, reached magnitude VI in Curacaví, La Calera, Los Andes, Peñaflor, San Antonio, Valparaíso, and Viña del Mar; and magnitude V–VI in Concón, Constitución, Curicó, La Ligua, Melipilla, Papudo, Pichilemu, Puchuncaví, Quilpué, and Villa Alemana.^[3] The earthquake was felt throughout much of central Chile from La Serena to Osorno. It was also felt in Mendoza, San Juan, San Luis, Córdoba, Tucumán, and Santa Fe provinces in Argentina.^[2] According to national radio networks, the tremors "were felt along a 1,000-mile stretch of Chile from Copiapó in the north to Valdivia in the south and across the Andes mountains in Argentina".^[9]

Although it has been considered by the news media as an aftershock of the 3 March 1985 earthquake,^[8] according to Rosa Urrutia de Hazbún and Carlos Lanza Lazcano's book Catástrofes en Chile 1541–1992, this earthquake was a different and separate event.^[10]

Mario Pardo, the director of the Chilean Seismological Service, told international press in April 1985 that it was "apparently an aftershock from the 3 March earthquake that killed 177 in central Chile" and that "the quake was centered in the ocean off the coast near Pichilemu, a city 100 miles southwest of Santiago".^[9]

According to national radio networks, the tremors "were felt along a 1,000-mile stretch of Chile from Copiapó in the north to Valdivia in the south and across the Andes Mountaines in Argentina".^[9]

Damage and effects

Two people died of heart attacks after the earthquake; one in Santiago and another in Chillán.^[2]^[11] The earthquake lasted approximately three minutes according to The New York Times.^[11]

It created damage in addition to that already caused by 3 March earthquake in the Santiago-Valparaíso area.^[2]

Hundreds of people panicked into the streets, while radio stations reported some brief power blackouts. In Valparaíso, the roof of a house collapsed, while other houses fell down in Curacaví. No injuries were reported.^[9]

Previous events

A magnitude 8.0 earthquake was registered on 3 March 1985 offshore Valparaíso, Valparaíso Region.^[1] It reached a maximum intensity of IX on the Mercalli intensity scale. 177 people were killed, 2,575 injured, 142,489 houses were damaged and about a million people were left homeless.^[12] There was a long interruption on basic services, and the damage provoked by that earthquake was estimated to be more than 1,046 million US dollars.^[13]

References

^ ^a ^b "SISMOS IMPORTANTES Y/O DESTRUCTIVOS (1570 – Mayo 2005)" (in Spanish). Sismología Universidad de Chile. Archived from the original on 31 December 2006. Retrieved 8 September 2010.
^ ^a ^b ^c ^d "Historic Earthquakes". United States Geological Survey. Archived from the original on 4 November 2012. Retrieved 8 September 2010.
^ ^a ^b ^c "Sismo del 8 de abril de 1985" (in Spanish). Santiago de Chile: University of Chile Geological Service. 1985. {{cite journal}}: Cite journal requires |journal= (help)
^ "Terremotos de Chile (Historia)".
^ ":: SISMO24.CL :: Principales Terremotos en Chile, la noticias". Archived from the original on 3 December 2010. Retrieved 21 May 2016.
^ Luis Valenzuela (14 April 2010). "Planificación Urbana en Zonas de Riesgo" (PDF) (in Spanish). Universidad Católica de Chile. Archived from the original (PDF) on 12 March 2012. Retrieved 11 September 2010.
^ "Análisis de la sismicidad registrada por redes terrestres y submarinas" (PDF). Universidad de Chile (in Spanish). 1 July 2007.
^ ^a ^b "Estudio comparativo de los terremotos de subducción chilenos con los terremotos de subducción del norte, centro y sur de América" (PDF) (in Spanish). Concepción, Chile: University of Chile Seismological Service. 16–19 November 2005. Archived from the original (PDF) on 27 February 2013. Retrieved 12 September 2010.
^ ^a ^b ^c ^d "Powerful quake shakes up Chile". The State. Columbia, South Carolina. 9 April 1985. p. 2. Pardo said the quake was centered in the ocean off the coast near Pichilemu, a city 100 miles southwest of Santiago.
^ Urrutia de Hazbún, Rosa; Lanza Lazcano, Carlos (1993). Catástrofes en Chile, 1541–1992 (in Spanish). Santiago de Chile: Editorial La Noria. Retrieved 13 September 2010.
^ ^a ^b "Strong quake jolts Chile". The New York Times. Associated Press. 8 April 1985. Archived from the original on 27 February 2013. Retrieved 8 September 2010.
^ "Terremoto de 1985" (in Spanish). Angelfire. Archived from the original on 4 August 2010. Retrieved 12 September 2010.
^ "Grandes Terremotos en Chile". El Mercurio. Santiago de Chile. Archived from the original on 7 February 2012. Retrieved 12 September 2010.