1970 Colombia earthquake

The 1970 Colombia earthquake occurred in Colombia on July 31.

1970 Colombia earthquake
UTC time1970-07-31 17:08:05
ISC event794176
USGS-ANSSComCat
Local dateJuly 31, 1970 (1970-07-31)
Local time12:08:05
Magnitude8.0 Mw [1]
Depth645 km (401 mi) [1]
Epicenter1.6°S 72.53°W / -1.6; -72.53 [1]
Areas affectedColombia
Casualties1 dead, several injured [2]

Details and aftermath

The shock killed one person and injured several others. Because it was a deep-focus earthquake, shaking occurred over an extensive area, including San Juan, Bogotá, Caracas, Buenos Aires, and São Paulo; it was felt as far north as Mexico City.[3] Its depth forestalled more serious casualties,[3] and there were no aftershocks.[4]

The depth of the earthquake prompted scientists in South America to install seismometer networks focused on long-period earthquakes.[3] Until the 1994 Bolivia earthquake, the 1970 Colombia earthquake was famous among seismologists as the largest deep earthquake.[5]

Analysis

A study completed by Dziewonski and Gilbert (1974) determined that the earthquake had featured isotropic compression, or an increase in density near the rupture point similar to an implosion;[6] this was released to great controversy.[5] They also claimed that the compression had been initiated 80 seconds before the actual earthquake's short-period shaking. Many studies have reached differing conclusions including a dearth of isotropic movement, and many scientists feel that resolution created errors in Dziewonski and Gilbert's findings.[7] In 1997, Russakoff, Ekstrom, and Tromp reassessed their findings utilizing more advanced equipment that factored in shear wave splitting and coupling (the measure of how tightly locked two sides of a fault or plate are) and confirmed that there was very little isotropic compression.[5]

See also

References
  1. ISC (2015), ISC-GEM Global Instrumental Earthquake Catalogue (1900–2009), Version 2.0, International Seismological Centre
  2. IISEE. "IISEE Catalogue Search parameters page". Catalog of Damaging Earthquakes in the World. Retrieved August 18, 2013.
  3. "Historic Earthquakes: Colombia 1970". United States Geological Survey. November 1, 2012. Retrieved July 30, 2013.
  4. Karato, Shun'ichiro (2003). The Dynamic Structure of the Deep Earth: An Interdisciplinary Approach. Princeton University Press. p. 162. ISBN 978-0691095110.
  5. Russakoff, Ekstrom, and Tromp, pg. 20423.
  6. Kennett, L.N.; Simons, R.S. (1976). "An Implosive Precursor to the Colombia Earthquake 1970 July 31". Geophysical Journal International. 44 (2): 471. Bibcode:1976GeoJI..44..471K. doi:10.1111/j.1365-246X.1976.tb03668.x.
  7. Russakoff, Ekstrom, and Tromp, pg. 20424.

Bibliography
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