I am a professor in Geological Sciences and CIRES at the University of Colorado Boulder. My research group addresses problems in earthquake seismology, tsunami studies, active tectonics, and geophysical imaging of the subsurface. Research topics include deep structure and tectonics of mountain regions including the Rocky Mountains, Himalaya, and Southern Alps, subduction zone seismicity and structure, tsunami modeling using seafloor pressure measurements, tsunami forecasting with data assimilation, and studies of induced seismicity. Our work is field- and computer- based; we deploy seismometers, including ocean bottom seismometers, to record earthquakes and tsunamis as signals; we deploy geodetic and electromagnetic instruments, for tectonic studies and subsurface imaging complementary to seismology. The data sets that we collect are processed using modern algorithms, with significant emphasis on time series analysis, signal detection, and imaging technologies. Novel computational techniques include data assimilation, subspace detection, and interferometry.
Subduction zone studies: Sheehan is a PI on the Alaska Amphibious Array Community Seismic Experiment (AACSE) and the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip (HOBITSS) experiments. Both of these projects involved the deployment of ocean bottom seismic and pressure sensors to study subduction zone processes including slow slip, megathrust earthquakes, and tsunamis. Graduate students and postdocs on these projects have worked on seismicity, attenuation, and tomography.
Induced seismicity: Sheehan’s seismology group, in close collaboration with the hydrogeology group of Professor Shemin Ge, also in the Department of Geological Sciences, has made numerous contributions in recent years to studies of human-induced seismicity. Sheehan’s group has an ongoing experiment in northeast Colorado and maintains a webpage with direct access to real time seismic data from throughout Colorado at earthquake.colorado.edu
Continental crust and mantle imaging: Sheehan’s group made many early contributions to the use of converted seismic wave imaging and anisotropy studies of the continental lithosphere. Current method development includes coda wave autocorrelation interferometry, with the goal of better utilizing short-term but dense deployments of seismometer, with targets including crustal faults at depth.
Tsunami studies: A relatively new focus of the Sheehan group is in tsunami studies. This grew out of Sheehan’s involvement with ocean bottom seismic experiments, and the recognition that tsunami signals were well-recorded on the pressure sensors associated with such deployments. This has led to productive collaborations with international researchers and new development of in-house expertise.
Geomagnetics: Sheehan has co-advised graduate students with the local NOAA and USGS geomagnetic groups. Recent publications include a magnetotelluric study of the Rio Grande Rift (Feucht et al., 2019), and use of ocean tidal magnetic signals to study patterns of ocean circulation (Schnepft et al., 2018).
Honors and Awards
- AGU Fellow, 2014