A 2006 Colima Rift Earthquakes Series and Its Relationship to the Rivera-Cocos Plate Boundary
2015; Science Publishing Group; Volume: 4; Issue: 1 Linguagem: Inglês
10.11648/j.earth.20150401.12
ISSN2328-5982
Autores Tópico(s)High-pressure geophysics and materials
ResumoFrom 31 July through 13 August 2006 a series of fourteen earthquakes (M 3.9 to 6.1) occurred in the western end of the Central Mexican Volcanic Belt (CMVB) in a twenty-five days period. The most prominent earthquake (Mw 6.1) occurred on 11 August 2006 at 14:30 UTC (9:30 local time) approximately at 18.37° N, 101.25° W and 81 km depth. The epicenter was less than 40 km from Huetamo, Michoacan a 41,250-inhabitant city and 60 km from the El Infiernillo dam embayment the third largest hydroelectric plant in Mexico. This earthquake was widely felt with minor to moderate reported damage. In Mexico City 250 km away from the epicenter the earthquake produced alarm among the population and several buildings were evacuated. The earthquakes series developed into two activity clusters one centered in the coast and separated about 300 km from a second inland cluster. The initial coastal cluster consisted of a nearly linear activity distribution, which includes shallow-depth earthquakes of reverse and normal faulting mechanisms. The inland cluster shows more compact and deeper hypocenters distribution. Earthquakes first-motion polarities indicate that ruptures occurred as a normal faulting, which is a characteristic of the CMVB earthquakes. The overall trend of earthquakes distribution shows two branches, one, along the El Gordo-Colima graben system direction (~N45°E) nearly perpendicular to the coast and another along an east-west direction parallel to the southern border of the CMVB. Our results indicate that these two branches might constitute part of the continental extension of the Rivera-Cocos plate boundary.
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