Anne F. Sheehan
Ph.D. Massachusetts Inst. of Technology, 1991
Professor of Geophysics (Geophysics Program)
Associate Director, Solid Earth Sciences
E-mail: afs-at-cires.colorado.edu
Office: ESCI 440A
Phone: 303-492-4597
Web: Sheehan Research Group
Research Interests
Seismology, Geophysics, Earth Structure
Current Research: Imaging the Roots of the Rocky Mountains: The Bighorn Arch Seismic Experiment
With colleagues from Texas A&M University, the University of Wyoming, the University of Texas at El Paso, and Colorado College, I am currently conducting a large seismic imaging experiment centered on the Bighorn Mountains in Wyoming. The Bighorn Arch Seismic Experiment (BASE) is a flexible array experiment integrated with Earthscope transportable seismic array (USArray).
The goal of BASE is to develop a better understanding of how crustal basement-involved foreland arches form and what their link is to plate tectonic processes. To achieve this goal, the crustal structure under the Bighorn Mountain Range, Bighorn Basin, and Powder River Basin of northern Wyoming and southern Montana are being investigated with both structural geology and seismology. BASE incorporates seismic studies through the use of broadband and short-period seismometers, active- and passive-source “Texan” instrumentation, and structural geology of the Bighorn Mountains. The three-phase seismic deployment includes 39 broadband seismometers (15 months); 185 short-period seismometers (including three, five-element mini-arrays for six months); and 1,850 active-source and 800-passive source Texan instruments (two weeks). The passive-source experiment began in the summer of 2009 and the active-source experiment will take place in the summer of 2010.
CIRES graduate students Henry Berglund and Kevin Befus at Bighorns broadband seismic station west of Kaycee, WY.
The novel combination of these approaches and anticipated simultaneous data inversion will give a detailed structural crustal image of the Bighorn region at all levels of the crust. The density of the sampling will allow us to make seismic reflectionstyle images that penetrate the crust. Four models have been proposed for the formation of the Bighorn foreland arch: subhorizontal detachment within the crust, lithospheric buckling, pure shear lithospheric thickening, and fault blocks defined by lithosphere-penetrating thrust faults. Each of these models results in a specific resolvable crustal structure. Combining information from these models with our results will lead to our final goal: a complete four-dimensional (including temporal) lithospheric-scale model of arch formation. This, in turn, will advance our understanding of the mechanisms accommodating and driving basement-involved arch formation as well as continental lithospheric rheology. More information on the project can be found at www.bighorns.org.
Additional funding has been obtained in collaboration with Los Alamos National Laboratory from the National Nuclear Security Administrationand the U.S. Air Force Research Laboratory for expanding the experiment for source-discrimination studies. We will assess the performance of regional seismic discriminants as they are applied to earthquakes, contained single-fired explosions, delay-fired mining explosions, and mining collapses using the unprecedented spatial sampling presented by the BASE dataset. The U.S. Air Force funding supports expansion of the active-source experiment to include additional single-fired shots, including our own single-fired shots at mines in close proximity to delay-fired shots, and it funds the deployment of three, five-element mini-arrays.
Publications
Click here for a complete list of published works »
PDF files of Sheehan publications can be found on the Sheehan Research Group site.
Also ...
Sheehan is a member of the CIRES Professor.
