SCEC Award Number 12154 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title Improving the Community Geodetic Model with GPS and InSAR
Investigator(s)
Name Organization
David Sandwell University of California, San Diego Yuri Fialko University of California, San Diego Javier Gonzalez Centro de Investigacion Cientifica y de Educacion Superior de Ensenada (Mexico) Bridget Smith-Konter University of Texas at El Paso Robert McCaffrey Portland State University Yuehua Zeng United States Geological Survey
Other Participants Xiaopeng Tong - UCSD grad student
Alejandro Gonzalez - CICESE grad student
SCEC Priorities 1d, 2d, 1e SCEC Groups Geodesy, SDOT, WGCEP
Report Due Date 03/15/2013 Date Report Submitted N/A
Project Abstract
 Surface crustal velocities are one of the key boundary conditions needed for developing 3-D quasi-static stress models. The quality and quantity of GPS and InSAR data are increasing rapidly and many groups are developing detailed crustal velocity models. We have identified two areas of weakness in these models - the southernmost SAF system in the Mexicali Valley and the small-scale deformation near faults having shallow interseismic slip. Our proposed role in this activity includes the following:
1. Collaborate with other SCEC and PBO scientists to develop a time-dependent Community Geodetic Model (CGM) at ~500 m resolution.
2. Work with CICESE scientists to acquire spatially dense GPS velocities across the Imperial and Cerro Prieto Faults in the Mexicali Valley to better constrain the velocity field of the southermost SAFS.
3. Participate in SCEC workshops related to the development of the Community Geodetic Model as well as the Community Stress Model.
Intellectual Merit One of the new priorities of SCEC4 is to investigate stress transfer from plate motion to crustal faults. Plates are driven by global scale forces mostly from subduction zones, asthenospheric drag, and ridge push. Away from plate boundaries the vector velocity and tensor stress fields are thought to have large scale (> 100 km) variations with position. However close to a plate boundary such as the San Andreas Fault System, velocity and stress become spatially variable over a variety of length scales ranging from the thickness of the lithosphere (~50 km) to the depth of the seismogenic zone (~10 km) to the thickness of the fault zone (~500 m) to the length scale of individual asperities (<100 m). Our proposed research will refine the surface velocity models to provide better data for constraining stress and stress rate models.
Broader Impacts More refined geodetic models derived from InSAR and GPS can constrain the rapid velocity gradients near the faults, which are critical for understanding the along-strike variations in stress accumulation rate and associated earthquake hazard.
Exemplary Figure Figure 3. The right figure shows the participants in our 2012 Mexicali Field survey from CICESE and SIO