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Evidence for great tsunamigenic earthquakes (M 8.6) along the Mexican subduction zone

Gerardo Suarez and Paola Albini
Evidence for great tsunamigenic earthquakes (M 8.6) along the Mexican subduction zone
Bulletin of the Seismological Society of America (April 2009) 99 (2A): 892-896


A very large earthquake took place on 28 March 1787 along the Mexican subduction zone. A unique characteristic of the 1787 event is the large tsunami reported at various coastal locations in southern Mexico. The segment of the coast affected by the strong tsunami coincides with locations where high felt intensities (modified Mercalli intensity [MMI] >VIII) were reported. Assuming, as is generally the case for large and great earthquakes in Mexico, that the fault rupture of the 1787 earthquake encompasses the areas where intensities greater than VIII were reported and where a strong tsunami invaded land, the estimated length of the rupture is approximately 450 km long. This fault length would correspond to an earthquake of approximately M (sub w) 8.6. In the instrumental record there is no evidence of earthquakes of this magnitude in the Middle American subduction zone. This evidence indicates that the rupture area of the 1787 earthquake was at least three times longer that those normally observed for earthquakes that take place in the Mexican subduction zone. The 1787 earthquake appears to have ruptured a long fault segment that more recently broke in earthquakes of more moderate magnitude (M (sub w) 7-8) and relatively short recurrence times of about 30 to 40 yr. Examples of this mode of variable rupture length where great but infrequent earthquakes rupture the fault areas of relatively smaller and more frequent earthquakes have been observed in the Sumatra-Andaman and Colombia-Ecuador plate boundaries, among others.

ISSN: 0037-1106
EISSN: 1943-3573
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 99
Serial Issue: 2A
Title: Evidence for great tsunamigenic earthquakes (M 8.6) along the Mexican subduction zone
Affiliation: Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, Mexico City, Mexico
Pages: 892-896
Published: 200904
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 21
Accession Number: 2009-042651
Categories: SeismologyEnvironmental geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, sketch maps
N16°00'00" - N22°00'00", W105°00'00" - W94°00'00"
Secondary Affiliation: Istituto Nazionale di Geofisica e Vulcanologia, ITA, Italy
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200924
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