Another USGS Mendenhall postdoctoral opportunity

Earthquake physics in the near-source region

As part of EarthScope, the San Andreas Fault Observatory at Depth, SAFOD,
is being built directly within the San Andreas Fault to measure the
physical and chemical conditions under which earthquakes occur. SAFOD lies
just north of the rupture of the 2004 Parkfield earthquake, where the fault
is moving through a combination of aseismic creep and repeating
microearthquakes. The SAFOD borehole begins 1.8 km west of the San Andreas
Fault, and passes through the entire fault zone into relatively undisturbed
rock on the east side.

An array of instruments, including accelerometers, seismometers,
tiltmeters, pressure transducers and thermistors will be installed in SAFOD
within or very near the rupture patch of several magnitude 2 and smaller
earthquakes at a depth of about 3 km. The key scientific objectives for
the instruments will be to monitor, in the near-field, the processes
associated with nucleation, propagation and arrest of earthquakes.
Specific goals include:

. Monitoring tilt, pore pressure and temperature during the cycle of
repeating microearthquakes.
. Observing earthquake nucleation and rupture processes in the near
field.
. Modeling stress transfer and earthquake interaction between repeating
earthquake sources.

In addition, SAFOD will 1) obtain physical samples (cores, cuttings, and
fluids), 2) measure stress, heat flow, fluid pressure and physical
properties within and adjacent to the San Andreas Fault Zone, and 3) make
repeated measurements of casing deformation to document the locations,
widths and rates of shearing associated with active faults crossing the
borehole. This combination of physical samples, in-situ measurements, and
long term observation of earthquake activity will provide a fundamentally
new and comprehensive view of earthquake processes.

The incumbent will be expected to develop a research plan utilizing SAFOD
data to formulate and test dynamic theories of earthquake nucleation and
rupture propagation.

Understanding the non-linear processes that lead to earthquake nucleation
has been recognized as a critical step along the path to determine the
limits of predictability for earthquakes. SAFOD provides the best
opportunity anywhere in the world to understand how earthquakes work. As a
full partner with the National Science Foundation and Stanford University in
SAFOD, the USGS has already made substantial investments in every phase of
the SAFOD experiment. This postdoctoral opportunity will continue our
leadership and deep involvement as the observatory moves into its most
critical and potentially rewarding period.

Proposed Duty Station: Menlo Park, CA

Areas of Ph.D.: Geophysics, physics

Qualifications: Applicants must meet one of the following qualifications:
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 Personnel specialist.)

Research Advisor(s): William Ellsworth, (650) 329-4784, ellsworth@usgs.gov;
Steve Hickman, (650) 329-4807, hickman@usgs.gov; Mark Zoback, Stanford
University, (650) 725-9295, zoback@pangea.stanford.edu

Personnel Office contact: Cathy Shahan, (650) 329-4109, cshahan@usgs.gov