TEACHING & RESEARCH
Professor Emeritus of Geological Sciences
Geophysics, Seismology, and Tectonics
- Ph.D., 1982, Geophysics, University of Washington
- B.S., 1975, Engineering Physics, South Dakota State University
My area of specialization is seismology, which is a branch of geophysics. My research can be described as a mix of experimental, theoretical, and computational work directed at addressing earth science problems. I have extensive experience with deployments of modern passive seismic array instruments, having been involved in a continuous series of field projects running from the late 1980s to the present.
The current example is the OIINK project. I am, however, still actively involved in the St Elias Erosion and Tectonics Project (STEEP). This large, collaborative group is currently involved in consolidation of diverse results from that project. I plan to continue work in that area as the USArray is planned to be deployed in Alaska in the next 5 years.
My computational work has been largely devoted to data processing challenges posed by modern passive seismic arrays.
My recent work has largely focused on seismic imaging. My students and I have developed a unique technology in a direct imaging method we call plane wave migration (see publications below). This method produces results similar to a 3D seismic reflection volume but using teleseismic earthquakes as sources. We are currently using this method to probe the entire upper mantle of the US using the Earthscope Transportable Array and to look at shallower structure in order to understand the origins of the Illinois Basin using data from the OIINK experiment.
Other Research Interests
- Earthquake location and local earthquake tomography. Long-term interest in local earthquake tomography and the inseparable problem of earthquake location.
- Tectonics of Central Asia. Long-term interest in the tectonics of central Asia. Worked for many years in Kyrgyzstan, Kazakhstan, Tadikistan, and Turkmenistan.
- Nuclear Monitoring. Seismology has had a major role in the problem of monitoring underground nuclear testing for decades. I have worked at various elements of this problem during my career.
- Applications of geophysics to near-surface processes. Geophysical methods are of major importance for noninvasive investigations of processes in the top 10-100 m of Earth's surface. Much of my interest in this subject stem from experimental work as part of the applied geophysics course I teach.
I have an extensive software library. Follow this link for documention for my software library and some user manuals.
For the past several years I have been involved with the USArray Data Processing short course sponsored by the National Science Foundation through IRIS. Follow this link for a summary of key properties of data processing packages used by most seismologists in the world. Current students in that short course may find this information useful.