SCEC Award Number 14206 View PDF
Proposal Category Travel Only Proposal (SCEC Annual Meeting)
Proposal Title Development of a Workflow for Using Finite Element Models for Geodetic Inversions
Investigator(s)
Name Organization
Charles Williams GNS Science (New Zealand)
Other Participants
SCEC Priorities 1e, 1b, 5d SCEC Groups SDOT, Geodesy, Transient Detection
Report Due Date 10/10/2014 Date Report Submitted N/A
Project Abstract
 The overall goal of this project was to provide a simple workflow to allow the use of finite element models in geodetic inversions. This will allow the representation of factors such as variable material properties and topography that are not possible with the elastic half-space models typically used. The initial plan was to develop a generalized inversion framework using the PyLith finite element code (Aagaard et al., 2013); however, the most direct method turned out to be the development of a workflow that allowed the use of PyLith with the Defnode geodetic inversion code (McCaffrey, 1995; 2002). We have successfully used this workflow to invert for slow slip events (SSEs) along the Hikurangi subduction margin, New Zealand (Williams and Wallace, 2015).
Intellectual Merit This research contributes to our ability to perform more realistic geodetic inversions for fault slip, which is a primary source of information for slip models and fault behavior. Our initial results have shown that incorporating realistic material properties can have a significant effect on slip estimates inferred from geodetic data. Our results thus far are applicable to SSE inversions; however, we anticipate that similar differences will be encountered for both coseismic and interseismic studies. Providing more accurate slip estimates is fundamental to all branches of seismic studies.
Broader Impacts The software and workflow developed as part of this project may be used by other scientists for either research or teaching. They will also be incorporated into future Crustal Deformation Modeling workshops, which are co-sponsored by SCEC. The improved fault slip estimates provided by this project should enhance our understanding of seismic hazards.
Exemplary Figure Figure 2. SSE inversion results. (left column) The slip magnitudes predicted by OKGF inversions. The color and line contours are the slip magnitude. (middle column) The slip magnitudes predicted by PHomGF models. The line contours are the predicted slip, and the colors indicate PHomGF solution minus OKGF solution. (right column) The slip magnitudes predicted by PHetGF models. The line contours are the predicted slip, and the colors indicate the PHetGF solution minus OKGF solution. (first row) The September to December 2010 Manawatu event. (second row) The January to July 2013 Kapiti event. (third row) The March to April 2010 Gisborne event. (fourth row) The February 2013 Hawke’s Bay event. The black arrows are the observed horizontal GPS displacements, and the white arrows are predicted from the slip model shown. The depth contours are shown for the upper left plot. Figure is from Williams and Wallace (2015).