Assembly of a large earthquake from a complex fault system: Surface rupture kinematics of the 4 April 2010 El Mayor-Cucapah (Mexico) Mw 7.2 earthquake
John M. Fletcher et al., Departamento de Geologia, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Carratera Tijuana-Ensenada No. 3918, Zona Playitas, Ensenada, Baja California, C.P. 22860, Mxico. Published online 25 June 2014; http://dx.doi.org/10.1130/GES00933.1.
In this paper, John M. Fletcher and colleagues document the styles of ground failure and faulting associated with the 4 April 2010 Mw 7.2 Mayor-Cucapah earthquake, which was the largest earthquake to strike northern Baja California, Mexico in more than 100 years. This earthquake was special in many ways. It produced a rupture 120 km long on a fault system that was not previously known to exist. The fault system is complex and composed of at least seven individual faults with distinct orientations and senses of slip. One of the faults is inclined at a very shallow angle (as low as 20 degrees) and is an example of a class of faults that is very controversial. The controversy centers on the fact that they violate basic theories of faulting for regions where the crust is being extended, which is the case for the northern Gulf of California. Additionally, slip on such faults is extremely rare in the historical seismic record. Thus this earthquake provides a unique opportunity to understand this controversial class of faults as well as to add to our know
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