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USGS Mendenhall Postdoctoral Research Fellowship Program

17-4. From slip rates to hazard models

Geologic slip rates are an essential input in seismic hazard models, including the USGS National Seismic Hazard Model (NSHM) and the Uniform California Earthquake Rupture Forecast 3 (UCERF3). However, confidence in hazard models depends on robust slip rate measurements, such as those derived from multiple sources with uncertainty ranges that encompass possible spatial and temporal variations. Incorporation of slip rates into hazard models can be problematic without a complete inventory of the sources of uncertainty that are often deeply hidden or ignored in reported slip-rate measurements.

We seek a Mendenhall Fellow who can make fundamental contributions toward broadening our understanding of geologic slip rates and improving methods for incorporating these measurements in seismic hazard models. Applicants are expected to be able to apply elements of geology, geodesy, geophysics, statistics, and modeling toward addressing this challenging problem. A focus on the Basin and Range Province or the San Andreas fault system of North America is welcome but not required. Proposals that leverage existing geologic, geodetic, and geophysical datasets are encouraged.

Key questions that may be addressed by research into slip rate include (but are not limited to): Are geologic slip rates more uncertain than typically reported? What are the most significant sources of uncertainty in geologic slip rate measurements? Which statistical measures of uncertainty are most useful for hazard modeling? How do temporal variations in slip rate (secular variation in slip) contribute to this uncertainty? How do spatial variations in slip rate (e.g. slip rate variations along strike) affect hazard models? What is the optimal number of earthquake cycles that should be sampled for a robust/stable slip rate measurement to use in seismic hazard models? What are the implications for NSHM- and UCERF3-style models that seek to capture the full range of uncertainties?

Research topics of interest include:

  1. Modeling studies based on existing or synthetic data to quantify statistical confidence in geologic slip rate and explore the temporal and spatial stability of slip rates for faults with varying recurrence intervals and slip-per-event. Use these modeling efforts to identify the “best” slip rate measurements and uncertainties for seismic hazard modeling.
  2. Documentation of the methods and approaches that can best be employed by the research community to encapsulate a robust geologic slip rate. Establish standard methods for reporting uncertainty.
  3. Assessment of statistical confidence of changing slip rates on faults and an exploration of the number of independent measurements needed to constrain these variations.
  4. Are there parameters other than slip rates that can provide essential constraints on hazard models? If so, what are realistic approaches to the problem?
  5. Determine how to best combine geologic and geodetic rates, given the complementary but wide range in earthquake cycle timescales and spatial coverage they provide.

The above are intended to be illustrative and are not intended to preclude other innovative research topics. Interested applicants are strongly encouraged to contact the Research Advisors, below, early in the application process to discuss project ideas.

Proposed Duty Station: Golden, CO or Pasadena, CA

Areas of Ph.D.: Geology (paleoseismology, neotectonics, Quaternary geochronology), geodesy, geophysics, 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 one of the following qualifications: 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.)

Research Advisor(s): Ryan Gold, (303) 273-8633,; Rich Briggs, (303) 273-8465,; Chris DuRoss, (303) 273-8544,; Kate Scharer, (626) 583-7240,; Peter Powers, (303) 273-8467,; Eileen Evans (California State University Northridge), (818) 677-5026,

Human Resources Office Contact: Melissa Barnhart, mabarnhart@usgs.govv, 916-278-9412

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