SCEC Award Number 19189 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title Testing Structural Model Predictions Against Geodetic Data in the Western Transverse Ranges, Southern California
Investigator(s)
Name Organization
Thomas Rockwell San Diego State University Scott Marshall Appalachian State University
Other Participants Yuval Levy
SCEC Priorities 3a, 1a, 3b SCEC Groups Geology, Geodesy, SDOT
Report Due Date 03/15/2020 Date Report Submitted 03/21/2020
Project Abstract
 For the western Transverse Ranges of southern California, USA, several conflicting subsurface structural models have been presented. Despite this, none of these models incorporated the full range of available geological observations, satellite geodetic data, and geophysical data. In this work, we test a recently published structural model for this region against vertical velocities measured by continuous GPS stations, and compare the results to previous structural models. While well data and structural modeling constrain the shallow fault structure, we show that GPS data can be used to constrain the dip angle of a deep ramp proposed for this region. We reduce the range of plausible dips from 16-30 (not using GPS) to 25-30 degrees (including GPS velocities as a constraint), and for the first time, present a structural model for this region that is consistent with the full range of available data. We suggest that a similar interdisciplinary approach could be applied in other regions in order to improve earthquake hazard assessments.
Intellectual Merit The results of this work will provide a more consistent 3D model of the entire western Transverse Ranges for inclusion in the SCEC CFM, thereby providing a platform for modeling earthquakes in the Western Transverse Ranges. By doing so it will have a direct impact on an area in Califor-nia which is inhabited by two million people. An additional contribution is the furthering of our understanding of the 4D evolution of this region. This work also demonstrates the resolving power of geodetic data when coupled with a realistic and well-constrained deformation model. Many types of data can constrain the shallow structure of faults, but this study demonstrates the utility of using geodetic data to resolve deeper portions of fault structure. Given that geodetic data is broadly available, this type of work could help to constrain many other fault systems in southern California and worldwide.
Broader Impacts This has supported a collaboration between a scientist in an undergraduate-only department (Marshall) and a well-established scientist at a research institute (Rockwell). The work was domi-nantly performed by an international Ph.D. student (Levy).
We hope that this type of study will be applied to many other fault systems as we have demon-strated that geodesy has resolving power for deep fault structure, even in zones of complex fault-ing.
Exemplary Figure Figure 4