[unav_all] Postdoc announcement from USGS

Jaime Magliocca magliocca at unavco.org
Tue Oct 27 10:21:32 MDT 2009


UNAVCO Community,

The U.S. Geological Survey (USGS) Mendenhall Research Fellowship Program
(http://geology.usgs.gov/postdoc/) provides opportunities for recent PhD
graduates (within 5 yrs since receipt of PhD) to conduct concentrated
research with members of the USGS professional staff.  Mendenhall
Fellowships are 2-year appointments with competitive salaries, benefits
packages, and project expense funds appropriate to the scope of research.

A research opportunity of particular interest to the UNAVCO community is:
33.  

Cascadia Subduction Zone Transient Aseismic Deformation and Its Possible
Relationship with Time-Dependent Earthquake Hazards

The Cascadia subduction zone, extending from northern California to
Vancouver Island, Canada, has a 10,000-year record of producing earthquakes
of M8.5 or greater at intervals of several hundred years. The last major
event, in 1700, was likely of magnitude 9, although paleoseismic data
indicate that past great Cascadia earthquakes have had a range of magnitudes
(Nelson and others, 2006). The subduction interface has remained seismically
quiet at about the magnitude 5 level for the duration of modern seismic
recording, but transient accelerations of aseismic slip downdip of the
anticipated megathrust rupture are now known to occur frequently throughout
the Cascadia forearc. These aseismic deformation episodes, which generally
occur simultaneously with low-frequency tectonic tremor, are increasingly
well documented by the greatly expanded networks of continuous GPS stations
and borehole strainmeters of the National Science Foundation funded Plate
Boundary Observatory, a component of the Earthscope initiative.

The relationship of aseismic slip events in Cascadia with time- dependent
earthquake hazard is an active topic of research. It has been argued that
episodes of accelerated aseismic slip are times when  the probability of a
megathrust rupture is elevated (Mazzotti and Adams, 2004). Spatial and
temporal correspondences between crustal  seismicity and slip events have
also been noted. There is a need for fundamental research on the
relationship of seismic and aseismic activity in Cascadia and this issue may
be illuminated by comparison with other subduction zones globally.

We seek an individual with experience in geodesy or seismology to pursue
research on the Cascadia aseismic slip events, ideally utilizing both the
strainmeter and continuous GPS components of the Earthscope Plate Boundary
Observatory. Research on the relationship of these events to Cascadia
earthquake potential is of particular interest. The postdoctoral researcher
will find this to be a very rich area of study. A few of the numerous
possible research topics include: forecasting Cascadia post-seismic slip and
its hypothetical implications for evolution of a Cascadia megathrust
earthquake sequence (foreshock identification); relationship of aseismic
slip events to major earthquakes; optimal utilization of strain and GPS data
to rapidly constrain depths and focal mechanisms of major earthquakes
offshore Cascadia; and development of algorithms to detect and locate
sources of aseismic deformation in near-real time.

If you are interested in this research opportunity, please contact Evelyn
Roeloffs (evelynr at usgs.gov), Nick Beeler(nbeeler at usgs.gov), Craig Weaver
(craig at ess.washington.edu), or Nathan Wood (nwood at usgs.gov)

Applications are due before November 9, 2009 for the current round of
fellowships.  Please note that a short research proposal is required as part
of the application.  Selections will be made in February 2010; start dates
will be between October 2010 and  March 2011.


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