SCEC Award Number 15170 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Estimating linear velocities, and earthquake and after slip parameters from continuous GPS time series
Investigator(s)
Name Organization
Robert McCaffrey Portland State University
Other Participants
SCEC Priorities 1d, 1e, 5b SCEC Groups Geodesy, SDOT, Seismology
Report Due Date 03/15/2016 Date Report Submitted 03/10/2016
Project Abstract
 The work performed was to extract from continuous and survey-mode GPS timeseries the linear velocities at the sites along with parameters that describe co-seismic slip and afterslip of recent earthquakes and volcanic deformation (1992-2016). From these parameters I developed steady-state and time-dependent deformation models for California. The time series were obtained from the CMM4 (Shen et al., 2011), the Plate Boundary Observatory, University of Nevada Reno continuous and survey-mode sites, San Bernardino survey sites from McGill et al. (2015) and the Pacific Northwest velocity field (McCaffrey et al. 2013). More than 2000 time series were inverted simultaneously to estimate the source parameters for 13 earthquakes (afterslip for 10 of them) along with volcanic deformation at Long Valley and Coso. The linear velocities estimated were then used to generate a steady strain rate map for California while the transient time histories provide a time-dependent strain rate map.
Intellectual Merit The work contributes to the seismic hazard assessment for California by improving fault slip rate estimates from geodetic data to be used in future hazard models. Development of time-dependent inversions will help uncover the long-term motions currently masked by transient signals. The work supports the goals of the SCEC Community Geodetic Model (an outgrowth of the Community Stress Model). The PI attended CGM workshops in September 2014 and January 2016 and the SCEC annual meetings in 2014 and 2015 where this work was presented.
Broader Impacts The work contributes to develop methods to enhance our understanding of earthquake hazards in California and vicinity. The software TDEFNODE was improved by this work and is made available freely to re-searchers upon request (web.pdx.edu/~mccaf/www/defnode).
Exemplary Figure Figure 5. Time snapshots of the second invariant of the time-dependent horizontal strain rate tensor derived from fitting transients to GPS time series. Each snapshot shows the strain rate averaged over 0.1 years.
Linked Publications

Add missing publication or edit citation shown. Enter the SCEC project ID to link publication.