Abstract

Complexities in the rupture process during a megathrust earthquake can be attributed to the combined effect of inhomogeneous distribution of stress accumulated during the interseismic period and inhomogeneous rheology of the seismogenic contact. We modeled the free-air gravity field of the southern Central Chile convergent margin along five 2-D profiles that cross the patch of highest slip during the Chilean 2010 megathrust earthquake in order to analyze variability in the density and shape of the continental wedge and its relationship with seismotectonics. We also analyzed the bathymetry to derive the long-term interplate friction coefficient. The results show that the high slip patch during the Maule earthquake corresponds to a segment of the margin characterized by (1) low densities in the continental wedge, (2) low vertical loading over the inter-plate contact, (3) a well-developed shelf basin and, (4) low taper angles consistent with a low effective basal friction coefficient. We interpret the correlation between these parameters in terms of the total potential energy change during the earthquake and conclude that if the normal stress or frictional coefficient are low, then a large slip does not necessarily imply a large amount of coseismic work. Heterogeneities in density of the continental basement can therefore be related to complexities in the pattern of coseismic slip and in the aftershock distribution. Locally, a subducted seamount or seaward spur of high-density continental crust may be present near the high slip patch.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.