SCEC Award Number 14216 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title AssessingUncertainties in Models of Postseismic Relaxation With Applications to the 2010 Mw 7.2 El Mayor Earthquake
Investigator(s)
Name Organization
Jean-Philippe Avouac California Institute of Technology
Other Participants John (Chris) Rollins, Grad Student
SCEC Priorities 1b, 1e, 2d SCEC Groups Geodesy, SDOT, SIV
Report Due Date 03/15/2015 Date Report Submitted N/A
Project Abstract
 SCEC4 funding has provided support for the development and testing of a new method to study the transient deformation following an earthquake, efficiently find a set of physical models that best fit the available data, and quantitatively assess the uncertainties and tradeoffs between relevant model parameters. This method represents a significant step towards directly inferring rheological parameters from geodetic data in a way that considers many deformation mechanisms simultaneously. We are applying this new method to the study of postseismic deformation following the 2010 M=7.2 El Mayor-Cucapah earthquake in Baja California, Mexico. This analysis not only sheds light on the properties of the crust and mantle in the Salton Trough - a region of great relevance to seismic hazard in southern California - but also produces models that can potentially be used directly within ongoing efforts to characterize the properties and state of stress on a regional scale such as the SCEC Community Stress Model.
Intellectual Merit This analysis not only sheds light on the properties of the crust and mantle in the Salton Trough - a region of great relevance to seismic hazard in southern California - but also produces models that can potentially be used directly within ongoing efforts to characterize the properties and state of stress on a regional scale such as the SCEC Community Stress Model. More generally, the method we have developed can be applied to any study of postseismic deformation and represents a significant step towards directly inferring best-fit rheological parameters from geodetic data in a way that considers many deformation mechanisms simultaneously.
Broader Impacts This project has built a collaboration between researchers at Caltech, the Earth Observatory of Singapore and the University of Cambridge and has been led by Chris Rollins, a former SCEC intern in the ACCESS program in 2009 and 2010. The project represents a significant step towards inferring properties of the Earth's lithosphere from geodetic data and its outputs can have a first-order impact on models of tectonic strain and seismic hazard.
Exemplary Figure Figure 3. a) Division of a 2D parameter space into Voronoi cells. Each sample (colored circles) is a dynamic forward model and its relative misfit to the data (color) defines that of the surrounding cell. b) Misfit to the data as a function of the viscosity of the asthenosphere in the model shown in Figure 2. This plot was produced from a four-dimensional sample set; the red boxes are the minimum value of the entire dataset for each viscosity value; the blue boxes are the maximum value of the entire dataset for each value; and the purple values are the values produced by integrating over the three dimensions not shown. Sampling is densest within the lowest-misfit region. c) Misfit to the data as a function of both the viscosity of the asthenosphere and that of the lower crust. The bottom, middle and top surfaces are the higher-dimensional versions of the red, purple and blue profiles in panel b, respectively. Figure constructed by Christopher Rollins.