SCEC Award Number 17093 View PDF
Proposal Category Collaborative Proposal (Data Gathering and Products)
Proposal Title Production of InSAR data and secular line-of-sight velocities of Southern California for the Community Geodetic Model
Investigator(s)
Name Organization
Gareth Funning University of California, Riverside Zhen Liu University of California, Los Angeles
Other Participants Rachel Terry (UCR)
SCEC Priorities 1a, 2a, 3e SCEC Groups Geodesy, CXM
Report Due Date 06/15/2018 Date Report Submitted 11/12/2018
Project Abstract
 The objective of the project is to produce InSAR data and estimate average deformation velocities in support of the SCEC Community Geodetic Model (CGM) project. We process SAR interferograms using archival data acquired by the European ERS and Envisat missions, spanning the period 1992–2011, from seven descending tracks covering the southern California region. This processing effort aims to supply standard interferogram products, produced according to a ‘best practice’ specification, developed at past CGM workshops, to be used to test time series inversion methods and to ultimately produce a combined GPS/InSAR consensus deformation product. To facilitate this, interferogram data produced under this project will be archived in the InSAR Product Archive at UNAVCO (https://winsar.unavco.org/insar/) for use by other CGM participants and in future CGM products. We apply the small baseline subset method to our processed interferograms to estimate average line-of-sight (LOS) velocities for each track. We find that the majority of the deformation captured by our InSAR data is consistent with plate-boundary parallel shear at rates of 3–4 cm/yr (equivalent to 1.0–1.3 cm/yr in LOS velocity), in a zone including the San Andreas and San Jacinto faults.
Intellectual Merit The project aligns well with and advances SCEC5 science goals. Development of community models is a SCEC5 Thematic Area, and our project directly addresses the Tectonic Geodesy research priority: “Produce a consensus secular velocity InSAR product using the full archive of SAR data (ERS, Envisat, ALOS-1) for the SCEC region.” (2017 Science Collaboration Plan, pg 19). The data products (interferograms and line-of-sight velocity maps) produced within the project will be used to answer what the fault loading rates in southern California are, and to constrain locations and amounts of off-fault deformation (both are SCEC5 ‘Basic Questions of Earthquake Science’).
Broader Impacts SCEC Community Models are inherently infrastructure projects, creating data products that will be used broadly, and for multiple purposes. This project explicitly is targeted to produce data in support of the Community Geodetic Model (CGM) project. Within SCEC and the earthquake science community, such products may be used in the construction of earthquake hazard models, which themselves have a much broader potential reach than just the earthquake science community – to industry, local government and society as a whole. Deformation datasets like the CGM can also be potentially useful for monitoring other processes, such as groundwater withdrawal/change, landsliding, subsidence and changes to vulnerable infrastructure. Our results are thus of potential use to many other groups.
Exemplary Figure Figure 2: Examples of InSAR line-of-sight (LOS) velocity maps for four of the tracks processed (see Figure 1 for locations). Velocities are wrapped at a 2 cm/yr interval. In each case, deformation across the main plate boundary fault structures is in the range 1.0–1.3 cm/yr in LOS velocity; locally, larger amplitude velocity features (small ‘blobs’) are collocated with groundwater basins and oil production fields.