Dale S. Sawyer
Professor

Research:

Geodynamics, Seismology

My current research focuses on the dynamic processes which have created continental margins. I use two tools in my studies: geodynamic modeling and wide-angle ocean bottom seismology. Geodynamic models of the rifting of continental lithosphere are not explaining many previously enigmatic observations at divergent continental margins. I use the finite element method running on a variety of machines up to supercomputer class to simulate the plate tectonic deformation of the upper 125 km of the earth. Along with a colleague at Rice, I have recently published a model which can explain why the character (location and style of rifting) of some rifts (including the US Atlantic margin and Australian Exmouth Plateau margin) changes during rifting from so called "simple" shear to "pure" shear.

I also use Ocean Bottom Seismometers to acquire wide-angle seismic data on divergent and convergent continental margins. Wide-angle seismic data are obtained when receivers are located both close to the shots, as in the more typical near-offset seismology, and also far from the shots. The data at a range of offsets (the distance between shot and reciever) are very useful for determining the velocity of sound waves in rocks, and from that identify the type of rocks, at great depth (up to about 40 km in the experiments I have done). During the last five years, I have been involved in field work in Cook Inlet Alaska, offshore South Carolina, Georgia and Florida, the Gulf of Mexico, and Antarctica. I have data from those cruises that can be used by my students, and I plan to continue acquiring these type of data.

Selected Publications

Bradford, J.H. and Sawyer, D. S., "Depth characterization of shallow aquifers with seismic reflection - Part II: Pre-stack depth migration and filed examples," Geophysics, (in press).

Condi, F. J., Zelt, C. A., Sawyer, D. S., and Hirasaki, G. J., "Gravity inversion for rifted margin deep structure and isostatic constraints," Geophysical Journal International, 138 (1999): 435-446.

Bradford, J.H., Sawyer, D.S., Zelt, C.A., and Oldow, J.S, "Imaging a shallow aquifer in temperate glacial sediments using seismic reflection profiling with DMO processing shallow aquifer in temperate glacial sediments using seismic reflection profiling with DMO processing ," Geophysics, 63 (1998): 1248-1256.

Pending Publications