SCEC Award Number 20177 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title Time-series InSAR analysis using ARIA standardized InSAR products in support of the Community Geodetic Model
Investigator(s)
Name Organization
David Bekaert National Aeronautics and Space Administration Gareth Funning University of California, Riverside
Other Participants Subcontract or JPL graduate-level internship for Simran Sangha from UCLA
SCEC Priorities 1a, 2a, 3e SCEC Groups Geodesy, SDOT, CXM
Report Due Date 03/15/2021 Date Report Submitted 05/10/2021
Project Abstract
 The SCEC Community Geodetic Model project is an attempt to produce a consensus set of processed InSAR and GNSS data that can be used by the scientific community for the purposes of constraining seismic hazard and tectonic behavior. We contribute to this effort using InSAR data from the Sentinel-1 satellites, processed routinely using a cloud-based system, under the Caltech-JPL Advanced Rapid Imaging and Analysis (ARIA) Center for Natural Hazards project (https://aria.jpl.nasa.gov/). The full archive of standardized Geocoded UNWrapped (GUNW) interferograms from 9 Sentinel-1 tracks that cover the entire state of California, is used to produce surface deformation velocity maps at a statewide scale. We validate these maps against GNSS velocity data, test the effectiveness of weather model-based troposphere corrections, and show some examples of deformation features apparent in the data, including subsidence of the San Joaquin Valley and shallow creep on the central San Andreas fault.
Intellectual Merit This project developed a robust work flow for routine estimation of regional-scale deformation velocities - in keeping with SCEC priorities to produce a Community Geodetic Model that can be used to measure strain accumulation and aseismic slip on faults, and also to identify and quantify off-fault deformation.
Broader Impacts This project supported a graduate student of color (Sangha). The methodologies devloped here could be used to study regional scale deformation in other regions. The statewide deformation velocity maps produced here could be used for many other applications beside seismic hazards - including study of subsurface fluid extraction (water, steam and hydrocarbons), magmatic processes, landsliding, infrastructure vulnerability and coastal subsidence - all of which would have potential societal benefits.
Exemplary Figure Figure 2: Line-of-sight surface velocities before (top row) and after (bottom row) applying tropospheric corrections. Left column shows velocities from ascending tracks; right column shows velocities from descending tracks. Velocities are referenced to a single GNSS station (black square) for each track; GNSS stations used for velocity comparisons are also marked (black dots) Note that as the Sentinel-1 tracks overlap at these latitudes by about a quarter to the east and west (see Figure 1) the different tracks are shown here in an ‘exploded view’ with the overlapping sections separated. Positive motions indicate motion of the ground towards the satellite, and vice-versa; thus the large negative velocity feature seen in the central tracks, corresponding to the San Joaquin Valley, is consistent with rapid subsidence – most likely due to groundwater extraction.