Time-dependent Creep Model of the Central Creeping Section of the San Andreas Fault From 21 Years of InSAR, GPS and Repeating Earthquakes

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The proposed work will address the advanced analysis, full integration, and careful interpretation of space-geodetic and seismic data over the central creeping section of the San Andreas. To this end, three time series of the surface deformation, using C-Band, L-Band and X-band SAR data and spanning period 1992-2013, will be generated. The SAR images are acquired by ERS1, 2, Envisat and ALOS and Cosmo-SkyMed satellites, which will be jointly explored with a dense network of GPS data and catalogue of repeating earthquakes, through a time-dependent inverse modeling scheme. This modeling scheme allows resolving the 4-dimensional distribution of slip in the upper crust. It also enables us to conduct a systematic and detailed study of the spatial and temporal association of the aseismic slip pulses and events. This project, in particular, is focused on exploring the nature of interactions between seismic and aseismic deformation processes that occur in the fault zone and characterizing the kinematic models of creep pulses along the Central San Andreas Fault (CSAF). Characteristic repeating earthquakes will provide unique information on transient activity in the Earth?s crust. Fault slip is tied to the mechanical properties of the fault zone rocks and adjoining crustal blocks and the proposed activity can also evaluate the first order changes of crustal properties. The time-dependent kinematic model of transient slip will also allow investigating the possible relationships between long-term, and short-term transient behavior.An improved understanding of the spatially and temporally varying deformation field of fault zones to great depth is critically important for understanding active tectonics, fault-fault interaction and the occurrence of large earthquakes. To this end the results from this NSF funded project will allow us to assess the role of aseismic fault slip transients in earthquake occurrence and clustering. We anticipate long-term societal benefits from improved understanding of aseismic slip transients, their relation to regional strain anomalies, and improved models of the earthquake cycle that should improve earthquake forecasts and intermediate to longer-term predictions. This project will also provide partial support for an early-career scientist as well as valuable research experience for two graduate students who are planned to directly involve in this project. The issues and results obtained from this research project will be incorporated in undergraduate and graduate teachings.