The 1982 Ometepec earthquake that struck Mexico's southwestern coast near Ometepec (Guerrero) on 7 June was a doublet earthquake that ruptured in two steps. The first happened at 06:52 UTC, the second five hours later at 10:59 UTC. Estimated magnitudes are 6.9 and 7.0 on the Ms scale, and 5.8 and 6.0 on the mb scale.[2][3][1] The maximum MM intensities were VII and VIII, respectively.Cite error: Invalid parameter in <ref> tagCite error: Invalid parameter in <ref> tag

1982 Ometepec earthquake
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UTC timeDoublet earthquake:    
 A: 1982-06-07 06:52:34
 B: 1982-06-07 10:59:38
ISC event 
 A: 596705
 B: 596720
USGS-ANSS 
 A: ComCat
 B: ComCat
Local date7 June 1982
Magnitude 
 A: 5.8 mb;Cite error: Invalid parameter in <ref> tag
6.9 Ms [1]
 B: 6.0 mb;Cite error: Invalid parameter in <ref> tag
7.0 Ms [1]
DepthA: 19.4 km[2]
B: 19.9 km;[3] 33.8 km[4]
Epicenter16°31′N 98°15′W / 16.51°N 98.25°W / 16.51; -98.25Coordinates: 16°31′N 98°15′W / 16.51°N 98.25°W / 16.51; -98.25
Areas affectedMexico

Mexico's southwestern coast is parallel to the 3,000 km (1,900 mi) Middle America Trench (MAT), where the oceanic Cocos plate (a remnant of the ancient Farallon plate) is being subducted under the North American plate, resulting in many major earthquakes.Cite error: Invalid parameter in <ref> tag Most earthquakes observed in this region are similar to earthquakes seen at other subduction zones, but in the vicinity of Ometepec they tend to occur as doublets.Cite error: Invalid parameter in <ref> tag This earthquake is unique in being (circa 2013) the "best documented doublet and for which near and teleseismic data are available", and has been extensively studied.Cite error: Invalid parameter in <ref> tag

The interruption of the main rupture that results in a doublet earthquake has been attributed to "asperities", patches in the fault where harder rock resists immediate rupture. However, study of this earthquake's aftershocks shows a discontinuity in their spatial distribution.Cite error: Invalid parameter in <ref> tag This has been interpreted as indicating a split in the subducting plate, where the plate is subducting at slightly different down angles on either side of the split.Cite error: Invalid parameter in <ref> tag

References

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  1. ^ Jump up to: a b c Astiz, Luciana; Kanamori, Hiroo (1984), "An earthquake doublet in Ometepec, Guerrero, Mexico." (PDF), Physics of the Earth and Planetary Interiors, 34 (1–2): 24–45 {{citation}}: Cite has empty unknown parameter: |1= (help).
  2. ^ Jump up to: a b Cite error: Invalid <ref> tag; no text was provided for refs named ISC 596705
  3. ^ Jump up to: a b Cite error: Invalid <ref> tag; no text was provided for refs named ISC 596720
  4. ^ ANSS, "Mexico 1982b: M 7.0 – Guerrero, Mexico", Comprehensive Catalog, U.S. Geological Survey{{cite encyclopedia}}: CS1 maint: postscript (link) .

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See also

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