1950 Calama earthquake
The 1950 Calama earthquake occurred near the Argentina–Chile border with an epicenter near Calama, Chile in the Atacama Desert on December 9. The event had a hypocenter depth of 113.9 km, beneath the Caichinque volcanic complex. It measured magnitude Mw 8.2 on the moment magnitude scale, making it the largest intermediate depth earthquake ever recorded on Chilean soil.[2][3] One person was killed and an unspecified number of people were injured in Calama.[1]
  | |
| UTC time | 1950-12-09 21:38:51 |
|---|---|
| ISC event | 896170 |
| USGS-ANSS | ComCat |
| Local date | December 9, 1950 |
| Local time | 18:38:51 (UTC-3) |
| Magnitude | Mw 8.2 |
| Depth | 113.9 km (70.8 mi) |
| Epicenter | 23.977°S 67.912°W |
| Type | Normal |
| Areas affected | Chile |
| Max. intensity | VII (Very strong)[1] |
| Casualties | 1 dead, "several" injured |
Tectonic setting
Earthquakes are frequent in Chile as it lies in the so-called Pacific Ring of Fire, where many of the world's active volcanoes and seismic activities are concentrated at. Off the coast of Chile, the Nazca Plate subducts beneath the South American Plate along the Peru–Chile or Atacama Megathrust, producing large earthquakes including the 1960 Chilean earthquake which had a magnitude of 9.5–9.6 on the moment magnitude scale.[4]
In some cases, intraslab earthquakes occur. These earthquakes do not occur on the subduction interface; rather they happen as a result of faulting within the downgoing Nazca Plate. Intraslab earthquakes can occur anywhere within the slab, which may be deeper than 600 km.
Earthquake
The quake was an intermediate-depth event which ruptured within the Nazca Plate. There, the plate dips at an angle of 20°–30° to the east, beneath the South American Plate.[5] This was the result of extensional stress acting on the Nazca Plate at an intermediate depth. It is the only earthquake with a rupture entirely beneath a continent rather than offshore. Based on its large seismic magnitude, the rupture area is estimated to be 6,000 km2, breaking through the thickness of the Nazca Plate along a vertically-dipping normal fault.[6][7]
References
- "Significant Earthquake Information". ngdc.noaa.gov. NOAA National Centers for Environmental Information. Retrieved 3 November 2021.
- "M 8.2 - 121 km SSE of San Pedro de Atacama, Chile". earthquake.usgs.gov. U.S. Geological Survey. Retrieved 3 November 2021.
- "Los terremotos en Chile (1570-2010)" [Earthquakes in Chile (1570-2010)]. memoriachilena.gob.cl (in Spanish). Retrieved 16 April 2022.
- Ruiz, Madariaga, Sergio, Raúl (February 2018). "Historical and Recent Large Megathrust Earthquakes in Chile". Tectonophysics. 733: 37–56. Bibcode:2018Tectp.733...37R. doi:10.1016/j.tecto.2018.01.015.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - S. Peyrat; J. Campos; J. B. de Chabalier; A. Perez; S. Bonvalot; M.-P. Bouin; D. Legrand; A. Nercessian; O. Charade; G. Patau; E. Clévédé; E. Kausel; P. Bernard; J.-P. Vilotte (28 November 2006). "Tarapacá intermediate-depth earthquake (Mw 7.7, 2005, northern Chile): A slab-pull event with horizontal fault plane constrained from seismologic and geodetic observations". Geophysical Research Letters. 33 (22). Bibcode:2006GeoRL..3322308P. doi:10.1029/2006GL027710. S2CID 53556522.
- Edgar Ka; Jaime Campos (1992). "The Ms = 8 tensional earthquake of 9 December 1950 of northern Chile and its relation to the seismic potential of the region". Physics of the Earth and Planetary Interiors. 72 (3–4): 220-235. Bibcode:1992PEPI...72..220K. doi:10.1016/0031-9201(92)90203-8.
- B. Delouis; T. Monfret; L. Dorbath; M. Pardo; L. Rivera; D. Comte; H. Haessler; J.P. Caminade; L. Ponce; E. Kausel; A. Cisternas (1997). "The Mw = 8.0 Antofagasta (Northern Chile) Earthquake of 30 July 1995" A Precursor to the End of the Large 1877 Gap". Bulletin of the Seismological Society of America. 87 (2): 427-445. CiteSeerX 10.1.1.1027.3805. doi:10.1785/BSSA0870020427.