Fault slip near the Earth’s surface directly impacts the built environment, including above-ground construction and buried lifeline infrastructure (e.g., water pipelines, telecommunications). Despite the significant risk resulting from shallow slip, knowledge of shallow fault processes and how they relate to deeper slip, remains extremely limited. This is problematic not only for forecasting the distribution of fault slip relative to the built environment (e.g., the emerging field of probabilistic fault displacement hazard analysis), but also for our basic understanding of how measurements of crustal deformation at Earth’s surface relate to fault zone processes. The latter is a critical component of two USGS flagship hazard products, the Uniform California Earthquake Rupture Forecast (UCERF) and the National Seismic Hazard Model (NSHM), that inform U.S. building code and insurance rates.
While our knowledge of shallow fault physics has up-to-now been limited by a lack of near-field geodetic data, development of new geodetic techniques over the last decade has led to spatially-coherent and high-resolution near-field datasets such as optical correlation images (e.g., SPOT) and point clouds from mobile laser scanning (MLS). Further, the co-seismic and post-seismic deformation field from several large earthquakes have now be captured with unprecedented spatial resolution, including the 2014 M6.0 South Napa, California, earthquake and the 2019 M7.1 and M6.4 Ridgecrest, California, earthquakes. These observations are supplemented by dense seismic network deployments that captured aftershock sequences and fault zone tomography, and coring into the South Napa fault structure.
Together, these datasets offer numerous opportunities for a post-doctoral fellow possessing originality, innovativeness, and independent research leadership skills to help the USGS and scientific community at-large better understand the physics of shallow deformation and hazards due to shallow fault rupture. Potential avenues of research include, but are not limited to, the following:
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Developing theoretical or geomechanical models of shallow rupture mechanics and validating them against observed near-field displacement observations.
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Developing new data processing or data mining techniques, to identify the rheology of shallow faults through models, post-earthquake geologic and geophysical investigations, shallow drilling and/or laboratory experiments.
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Developing kinematic or dynamic rupture models that embrace the high spatial resolution of these new geologic and geophysical data sets to image fault slip in detail.
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Designing new computational methods to accomplish any of the preceding.
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Analyzing samples in the laboratory to constrain mechanical properties and deformation mechanisms, or conducting analog laboratory experiments to investigate how the surface deformation responds to changes in subsurface loading and mechanical properties.
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Leading field experiments to identify time-dependent changes in fault structure and shallow post-seismic deformation.
Interested applicants are strongly encouraged to contact the Research Advisor(s) early in the application process to discuss project ideas.
Proposed Duty Station: Moffett Field, CA or Pasadena, CA
Areas of PhD: Geophysics, seismology, or related fields (candidates holding a Ph.D. in other disciplines, but with extensive knowledge and skills relevant to the Research Opportunity may be considered)
Qualifications: Applicants must meet the qualifications for: Research Geophysicist, Research Civil Engineer, Research Computer Scientist, Research Engineer (General), Research Geodesist, Research Geologist, Research Mathematician, Research Physicist, Research Statistician, Research Physical Scientist, Research Computer Engineer, Research Environmental Engineer, Research Mechanical Engineer
(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.)
Human Resources Office Contact: Beverly Ledbetter, 916-278-9396, bledbetter@usgs.gov
