1970 Colombia earthquake
|Date||July 31, 1970|
|Depth||651 km (405 mi)|
The 1970 Colombia earthquake occurred in Colombia on July 31.
Details and aftermath
The earthquake hit at 17:08 UTC on July 31, 1970. It registered 8.0 on the Richter scale, and it killed one person, injuring multiple others. Because it had a depth of 651 km (405 mi), it spread over an extensive area and caused shaking in San Juan, Bogotá, Caracas, Buenos Aires, and São Paulo; it was felt as far north as Mexico City. Its depth forestalled more serious casualties, and there were no aftershocks.
The depth of the earthquake prompted scientists in South America to install seismometer networks focused on long-period earthquakes. Until the 1994 Bolivia earthquake, the 1970 Colombia earthquake was famous among seismologists as the largest deep earthquake.
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; this was released to great controversy. 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. In 1997, Russakoff, Ekstrom, and Trump 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.
- IISEE. "IISEE Catalogue Search parameters page". Catalog of Damaging Earthquakes in the World. Retrieved August 18, 2013.
- "Historic Earthquakes: Colombia 1970". United States Geological Survey. November 1, 2012. Retrieved July 30, 2013.
- Karato, pg. 162.
- Russakoff, Ekstrom, and Trump, pg. 20423.
- Kennett and Simons, pg. 471.
- Russakoff, Ekstrom, and Trump, pg. 20424.
- Karato, Shun'ichiro (2003). The Dynamic Structure of the Deep Earth: An Interdisciplinary Approach. Princeton University Press. ISBN 978-0691095110.
- Kennett, L.N. and Simons, R.S. (1976). "An Implosive Precursor to the Colombia Earthquake 1970 July 31". Geophysical Journal International (Oxford University Press) 44: 471–482. Bibcode:1976GeoJI..44..471K. doi:10.1111/j.1365-246X.1976.tb03668.x.
- Russakoff, Daniel, Ekstrom, Goram, and Tromp, Jeroen (September 10, 1997). "A new analysis of the great 1970 Colombia earthquake and its isotropic component". Journal of Geophysical Research (American Geophysical Union) 102 (B9): 20,423–20,434. doi:10.1029/97jb01645.