Imaging tectonic creep along active faults is critical for measuring strain accumulation and ultimately understanding the physical processes that guide creep and the potential for seismicity. We image tectonic deformation along the central creeping section of the San Andreas Fault at the Dry Lake Valley paleoseismic site (36.468°N, 121.055°W) using three data sets with varying spatial and temporal scales: (1) an Interferometric Synthetic Aperture Radar (InSAR) velocity field with an ~100‐km footprint produced from Sentinel‐1 satellite imagery, (2) light detection and ranging (lidar) and structure‐from‐motion 3‐D topographic differencing that resolves a decade of deformation over a 1‐km aperture, and (3) surface fractures that formed over the 3‐ to 4‐m wide fault zone during a drought from late 2012 to 2014. The InSAR velocity map shows that shallow deformation is localized to the San Andreas Fault. We demonstrate a novel approach for differencing airborne lidar and structure‐from‐motion topography that facilitates resolving deformation along and adjacent to the San Andreas Fault. The 40‐m resolution topographic differencing resolves a 2.5 ± 0.2 cm/yr slip rate localized to the fault. The opening‐mode fractures accommodate
Contemporary earthquake hazard models hinge on an understanding of how strain is distributed in the crust and the ability to precisely detect millimeter-scale deformation over broad regions of active faulting. Satellite radar observations revealed hundreds of previously unmapped linear strain concentrations (or fractures) surrounding the 2019 Ridgecrest earthquake sequence. We documented and analyzed displacements and widths of 169 of these fractures. Although most fractures are displaced in the direction of the prevailing tectonic stress (prograde), a large number of them are displaced in the opposite (retrograde) direction. We developed a model to explain the existence and behavior of these displacements. A major implication is that much of the prograde tectonic strain is accommodated by frictional slip on many preexisting faults.
more » « less- Award ID(s):
- 1834807
- NSF-PAR ID:
- 10199806
- Publisher / Repository:
- American Association for the Advancement of Science (AAAS)
- Date Published:
- Journal Name:
- Science
- Volume:
- 370
- Issue:
- 6516
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- p. 605-608
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract cm/yr of fault slip. A 90% ± 30% of the 1‐km aperture deformation is accommodated over the several meter‐wide surface trace of the San Andreas Fault. The extension direction inferred from the opening‐mode fractures and topographic differencing is 40°–48° from the local trend of the San Andreas Fault. The localization of deformation likely reflects the well‐oriented and mature fault. -
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