Community Geodetic Model


The Community Geodetic Model (CGM) is being developed by the SCEC community to assist in the understanding of the interseismic, coseismic, postseismic, and hydrologic processes associated with the earthquake cycle along the complex fault network of the Southern San Andreas system. This activity supports several of the SCEC5 science questions including: How are faults loaded across temporal and spatial scales? What is the role of off-fault inelastic deformation on strain accumulation, dynamic rupture, and radiated seismic energy?

The CGM is built on the complementary strengths of temporally dense GPS data and spatially dense InSAR data. Much of the SCEC4 activity was focused on the assembly of GPS and InSAR data sets for measuring secular motions, comparing geodetically inferred fault slip rates with geological rates based on paleoseismic studies (e.g. UCERF3), and using geodetic observations to detect and investigate transient deformation. The quality and quantity of both GPS and InSAR data is rapidly improving to enable a breakthrough in the spatial and temporal resolution of the CGM. In particular, reprocessing of long GPS time series has provided high accuracy vertical measurements that reveal a wide range of new hydrologic and tectonic signals. In addition, two new C-band InSAR satellites (Sentinel-1A and B) are providing highly accurate systematic coverage of the entire SCEC region every 12 days from two look directions. Developing methods to integrate and update these dense spatiotemporal datasets will be a major task in SCEC5.

The CGM will include the following components:
- Time series and average velocities from continuous GPS sites.
- Time series and average velocities from campaign GPS sites.
- Consensus horizontal velocity and strain rate grids based on GPS.
- Line of sight (LOS) velocities at 500 m spatial resolution from archive of InSAR data (1992-2011).
- Time series from Sentinel-1 InSAR with 500 m spatial resolution, and better than seasonal temporal sampling.
-  A consensus vertical time series at better than seasonal resolution based on GPS and InSAR.

The SCEC CSM is a community effort informally steered by researchers with a range of tectonic and geodetic expertise including David Sandwell (UCSD), Willian Barnhart (U. Iowa), Peter Bird (UCLA), Brendon Crowell (UW), Gareth Funning (UCR), Eric Lindsey (EOS, Singapore), Rowena Lohman (Cornell), Rob McCaffrey (PSU),  Jessica Murray (USGS),  Zheng-Kang Shen (UCLA), Tom Herring (MIT), Wayne Thatcher (USGS), Xiaopeng Tong (UW), and Yuehua Zeng (USGS). For questions about this web page, please contact dsandwell@ucsd.edu.

If you're interested in participating in the CGM, you can request to be added to our e-mail list.

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