The probability, size, and effects of potential earthquakes on the faults in and near California’s Sacramento–San Joaquin River Delta (“Delta”) are poorly understood. The Delta is home to an extensive levee network critical to the success of a billion-dollar restoration and water supply reliability effort for the State of California and the safety of individuals living in the Delta region. Earthquake ground shaking may exacerbate vulnerabilities or cause catastrophic failure of Delta levees already susceptible to flooding and subsidence damage. Recent attempts to synthesize Delta hazards are not comprehensive, and many faults that may cause damaging earthquakes are not well-studied and have not been included in existing hazard analyses. This project seeks to reduce the uncertainty in seismic hazard within the Sacramento-San Joaquin Delta through the improvement in understanding of local earthquake sources.
In the Delta, potentially seismogenic faults and the effects of potential earthquake shaking are poorly constrained because the Delta sits farther from the largest Bay Area population centers than the principal faults of the San Andreas Fault system. Furthermore, the geologic setting in the Delta is difficult to study. The proximal seismic sources include reverse, thrust, and oblique faults that have lower slip rates than the dextral faults of the San Andreas fault system. These may deform the Earth’s surface without rupturing all the way to the surface or be buried by Delta sediments. These issues may require the use of innovative and sophisticated methods to characterize these faults. Given the geologic setting of the Delta, there may be several approaches taken to study hazard associated with potential seismic sources. These may include the study of: 1) faults that uplift and offset geomorphic markers such as river and fan terraces; 2) blind faults that are expressed as folds and growing anticlines; and 3) faults that are amenable to paleoseismic trenching investigation. Less direct methods including geophysical surveys and assimilation of various well log and geotechnical borings have the potential to help understand fault geometry and behavior on buried structures.
Applicants may choose to employ methods from paleoseismology, tectonic geomorphology, geophysics, geodesy, and/or other innovative approaches to reducing uncertainty in seismic hazard analyses in the Delta region. The overall goal will be to provide scientific products that seismic hazard modelers can use to constrain hazard models, and to provide scientific information useful to a wide range of decision-makers and infrastructure managers in the Delta region. These products may include fault locations, slip rates, and/or earthquake recurrence information.
Interested applicants are strongly encouraged to contact the Research Advisor(s) early in the application process to discuss project ideas.
Proposed Duty Station: Menlo Park, CA
Areas of PhD: Geology, geophysics, or related disciplines (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 Geologist, Research Geophysicist
(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: Audrey Tsujita, 916-278-9395, atsujita@usgs.gov
