T41A-2845
Heterogeneous Earth Structure, Deformation, and Slip During the 2010 Mw 7.2 El Mayor-Cucapah Earthquake from Geodetic Data
Thursday, 17 December 2015
Poster Hall (Moscone South)
Mong-Han Huang1, Haylee Dickinson2, Eric Jameson Fielding3, Jianbao Sun4, Andrew Mark Freed2 and Roland Burgmann5, (1)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (2)Purdue University, West Lafayette, IN, United States, (3)Jet Propulsion Lab Caltech, Pasadena, CA, United States, (4)Institute of Geology, China Earthquake Administration, Beijing, China, (5)University of California Berkeley, Berkeley, CA, United States
Abstract:
The 4th of April 2010 Mw 7.2 El Mayor-Cucapah (EMC) earthquake in Baja California and Sonora, Mexico has primarily right-lateral strike-slip motion and a minor normal slip component. The surface rupture extends about 120 km west of the boundary between the Pacific and the North American plates. The EMC event initiated near the center and ruptured bilaterally into an east-dipping strike-slip fault zone to the north and a west-dipping strike-slip zone to the south. Here we use geodetic measurements including GPS, InSAR (SAR interferometry), and sub-pixel offset measurements to characterize the fault slip during the EMC event. We use dislocation inversion methods to determine fault geometry as well as sub-fault slip distribution based on geodetic measurements. We find that assuming layered earth elastic structure increased the inferred deep slip (10-15 km depth) by up to 1.6 m (60%) compared to assuming a homogeneous elastic structure. Inferred slip was also strongly (up to 2 m) influenced by the choice of observational constraints used in the inversion. The choice of constraints also influenced the inverted seismic moment from Mw 7.20 to 7.26, and the difference is equivalent to a Mw 6.5 event. Our results show that the outcomes of coseismic inversions can vary greatly depending on the methodology, something that needs to be considered both for characterizing an earthquake and when using such results in subsequent studies of postseismic deformation.