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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS014 Oral Presentation 2252
Influence of the Along-Plate-Boundary rupturing on the subduction zone
earthquake intensity pattern: the january 21 (22), 2003, Colima, Mexico,
Across-Trench Earthquake (Mw 7.5)
Prof. Zobin Vyacheslav
Observatorio Vulcanologico Universidad de Colima, Mexico IAVCEI
The 2003 Colima earthquake (Mw 7.5) occurred along the across-trench structure of the El Gordo
Graben, which constitutes a boundary between the Cocos and Rivera oceanic plates near Mexican coast.
This earthquake was characterized by the downdip across-trench directivity of its rupture, as
reconstructed from seismic waveform modeling. It was a reason for the severe damage to buildings in
the localities situated at distances where usual along-trench rupturing subduction earthquakes of the
same magnitude do not produce any significant damage. A field investigation of residential house
damage in 83 localities of the Occidental part of Mxico allowed construction of macroseismic map of the
moment magnitude 7.5 2003 Colima earthquake. The macroseismic map of the 2003 earthquake shows
that the narrow (30 km wide) intensity VII MM zone was elongated (up to 60 km) in the NE direction
toward the continental part of Colima state. As a result, the intensity in Colima city was 1.5 grades
larger than would be expected for this magnitude according to the proposed attenuation of intensity
with distance relationship for earthquakes from the Mexican subduction zone.
Keywords: intensity, mexico, earthquake