- © 2012
Online material: Figures containing the Fourier spectra and acceleration time histories recorded at rock sites and soil sites for stations used in the simulations.
The Mw = 7.2 El Mayor-Cucapah earthquake occurred on 4 April 2010 in northern Baja California, about 48 km south of the border between Mexico and the United States at shallow depth along the plate boundary between the North American and Pacific plates. This earthquake was felt in the states of Baja California and Sonora, Mexico, and in southern California and Arizona in the United States. The continental plate boundary in northern Baja California consists of a series of strike-slip faults oriented in the NW-SE direction that are separated by pull-apart basins (Figure 1). The Pacific plate has a convergence rate of 4.8 cm/yr with respect to North America (DeMets et al. 1994).
Southern California and the northern part of Baja California form a common region affected by a number of regional-scale active faults that are part of a complex lateral system (Goff et al. 1987). The main faults in the epicentral and adjacent areas are the Imperial fault, the Cerro Prieto fault, and the Laguna Salada fault system. The Imperial fault has a length of 75 km and its orientation is N42°W. This fault has generated major earthquakes like the 18 May 1940, El Centro, California earthquake (M = 7.1) and the 15 October 1979, Imperial Valley, Mexico earthquake (M = 6.6). The relative motion of the Imperial fault with respect to North America (NA) is 4.7 cm/yr (Frez and González 1991). The length of the dextral fault of Cerro Prieto is about 80 km with a 5.0 cm/yr relative motion on the fault with respect to NA. Major earthquakes have also taken place on the Cerro Prieto fault in 1852, 1875, and …