SCEC Award Number 17156 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title Estimation of time varying strain rate in southern California: Detangling postseismic deformation from GPS measurements
Investigator(s)
Name Organization
Eric Hetland University of Michigan
Other Participants Trever Hines (graduate student at UM)
SCEC Priorities 2a, 1e, 1a SCEC Groups Geodesy
Report Due Date 06/15/2018 Date Report Submitted 11/12/2018
Project Abstract
 The project’s goal was to determine time-varying horizontal strain rates and vertical deformation gradients, complete with their uncertainties, from GPS/GNSS displacement series in southern California. We proposed to use our recently developed code PyGeoNS (Python-based GEOdetic Network Smoother), which is built upon a Gaussian process regression (GPR). GPR is a non-parametric, Bayesian method, resulting in a posterior estimate of time-varying strain-rates using a prior which describes the level with which transient deformation is expected to covary spatiotemporally. Due to a series of turnovers in graduate students, coupled with an administrative oversight in the project’s end-date, the work was not conducted. The original graduate student slated to work on the project accepted a job prior to the notification of the award of the project. A junior graduate student was then preparing to work on the project, when they unexpectedly had to leave the program. A newly recruited graduate student was preparing to start working on the project, when we learned that the project had already expired. We are still motivated to complete the project as proposed, but the timing just did not work out on this particular grant.
Intellectual Merit The project’s ultimate goal was to quantify transient strain-rates, complete with an estimate of their uncertainties, throughout Southern California. Determination of the strain-rates associated with postseismic deformation has the potential to further understand the secular strain rates and vertical deformation gradients, which can then be used to further constrain strain-accumulation models (P1.a & P1.b). Additionally, time-varying strain rates may yield insight into stress evolution in the upper crust (P1.e) and postseismic transient deformation. We proposed to use the postseismic strain rates to further constrain the mechanisms of postseismic deformation (P2.a related to relaxation of inelastic processes).
Broader Impacts It was our ultimate intention that the estimated time-dependent strain-rate data products would be of use to other researchers, for instance to constrain mechanical models of strain accumulation or postseismic deformation (P1.a & P1.b). To that end, we proposed to disseminate the derived data products widely. The PyGeoNS code is available for barrier-free access from the github.com code sharing repository.
Exemplary Figure N/A
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