1977 San Juan earthquake

Earthquake in Argentina 1977 San Juan earthquake Terremotosanjuan.jpg Argentina 1977-11-23 09:26:26 690743 iscgem690743 1977 11 23 yes 06:26:26 7.5 w y, 7.4 s y 15 km mi on 31.119 S 67.839 W region:ID_type:event inline,title Reverse X 65 deaths The 1977 San Juan earthquake, also known as Caucete earthquake, took place in the province of San Juan, Argentina, on 23 November at 06:26:26 AM. It measured 7.5 on the moment magnitude scale,ISC-GEM Global Instrumental Earthquake Catalogue (1900–2009) http://www.isc.ac.uk/iscgem/index.php 27 June 2022 International Seismological Centre Version 9.1 and had a maximum perceived intensity of X (Extreme) on the Mercalli intensity scale. The earthquake caused fatalities and severe damage to buildings throughout the province, especially in the city of Caucete, where at least 65 people died. It also caused slight damage in the north of the Greater Mendoza metropolitan area. Its were felt as far away as Buenos Aires, where people were awakened that Wednesday by the tremor. People left their houses at dawn in panic at the Argentinian capital, located at 1,000 km mi to the east southeast.February 2020 Tectonic setting San Juan Province lies in an area where the South American plate is affected by flat-slab subduction of the underlying Nazca plate, the so-called Pampean flat-slab. The very shallow angle leads to a much greater degree of coupling between the subducting and overriding plates. The increased coupling leads to shortening of the crust of the South American plate, causing active thrust tectonics and rapid uplift, forming the Sierras Pampeanas. The Pie de Palo range is one of the active structures, interpreted to be controlled by major thrust faults.Siame L.L. Sébrier M. Bellier O. Bourlès D. Costa C. Ahumada E.A. Gardini C.E. Cisneros H. 2015 Active basement uplift of Sierra Pie de Palo (Northwestern Argentina): Rates and inception from 10Be cosmogenic nuclide concentrations Tectonics 34 6 1129–1153 10.1002/2014TC003771 2015Tecto..34.1129S 55810378 https://hal-amu.archives-ouvertes.fr/hal-01458841/file/Modif.pdf The overall structure has been interpreted as both thin-skinned and thick-skinned. Earthquake The earthquake consisted of two sub-events, separated by about 20 seconds, treated by some seismologists as foreshock and mainshock.Langer C.J. Hartzell S. 1996 Rupture distribution of the 1977 western Argentina earthquake Physics of the Earth and Planetary Interiors 94 1–2 121–132 10.1016/0031-9201(95)03080-8 1996PEPI...94..121L The observed focal mechanism was reverse faulting, on a north–south trending structure. From the mainshock alone, it was not possible to decide whether the fault responsible dipped to the west or east. Analysis of the aftershock sequence suggests that two separate faults moved during the earthquake, the earlier event on a segment to the north and the later one to the south.Regnier M. Chatelain J.L. Smalley Jr R. Chiu J.-M. Isacks B.L. Araujo M. 1992 Seismotectonics of Sierra Pie de Palo, a basement block uplift in the Andean Foreland of Argentina https://www.researchgate.net/publication/236144911 Bulletin of the Seismological Society of America 82 6 2549–2571 The fault segments have been interpreted as both alternating west and eastward-dipping faults or as an east-dipping fault in the hanging-wall of a larger west-dipping fault.Bellahsen N. Sebrier M. Siame L. 2016 Crustal shortening at the Sierra Pie de Palo (Sierras Pampeanas, Argentina): near-surface basement folding and thrusting https://www.researchgate.net/publication/307955519 Geological Magazine 153 5–6 992–1012 10.1017/S0016756816000467 2016GeoM..153..992B free There was no surface rupture associated with the earthquake and it is an example of a blind thrust earthquake on thrust faults underlying the Pie de Palo range.Meigs A.J. Nabelek J. 2010 Crustal-scale pure shear foreland deformation of western Argentina Geophysical Research Letters 37 11 n/a 10.1029/2010GL043220 2010GeoRL..3711304M free Damage There was widespread damage in San Juan Province. The towns of Bermejo and Caucete were particularly badly affected. Many houses constructed of adobe or unreinforced masonry were either badly damaged or destroyed and very large areas were affected by liquefaction. More modern structures, built to earthquake resistant designs, in contrast showed little damage. At least 65 people were killed and a further 284 were injured. The extensive damage left many homeless, with estimates in the range 20,000 to 40,000.Rohjan C. https://pubs.usgs.gov/circ/1978/0762c/report.pdf Seismic engineering program report, September-December 1977 U.S. Dept. of the Interior, Geological Survey 1978 Porcella R.L. Geological Survey Circular 762-C 2–7 Preliminary Report on the San Juan Earthquake of November 23, 19777 The area's wine industry was heavily impacted due to damage to both buildings and particularly wine storage tanks, reducing the wine storage capacity of the affected area by about 10 million litres. See also List of earthquakes in 1977 List of earthquakes in Argentina References Keefer D. K. Youd T. L. T. Leslie Youd Liquefaction during the 1977 San Juan Province, Argentina earthquake (Ms = 7.4) Engineering Geology 211–233 37 3–4 1994 10.1016/0013-7952(94)90057-4 1994EngGe..37..211Y https://zenodo.org/record/1253864 International Handbook of Earthquake & Engineering Seismology Part A, Volume 81A A List of Deadly Earthquakes in the World: 1500–2000 T. R. Utsu 2002 Academic Press First 978-0124406520 683 External links Listado de Terremotos Históricos https://web.archive.org/web/20121002062655/http://www.inpres.gov.ar/seismology/historicos3.php 2012-10-02 es – Instituto Nacional de Prevención Sísmica 690743 1977 Category:Earthquakes in San Juan Province, Argentina San Juan, 1977 San Juan Earthquake, 1977 Category:Buried rupture earthquakes Category:November 1977 in South America