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Joyce McLaughlin

David Isaacson

Antionette Maniatty

Assad Oberai

Steven Roecker

Birsen Yazici

Mourad Zeghal

Research Scientists

Affiliates

Center Participants

Charles Addison Williams
Senior Research Scientist of Earth and Environmental Sciences
Rensselaer Polytechnic Institute

Education:
Ph.D., Geophysics (Planetary Sciences minor), University of Arizona, Tucson, 1990
M.S. Geophysics, University of Arizona, Tucson, 1987
B.A., Physics/Geology University of North Carolina at Chapel Hill, 1980
Completed Coursework in Math, U.S. Coast Guard Academy, 1976-1978

Career Highlights:
Williams served as a research assistant for six years while earning his master's and doctorate degrees from the University of Arizona in Tucson. He then held two postdoctoral research associate positions, first at Princeton University from 1990 -'92, then from 1992-'95 at the Lawrence Livermore National Laboratory in Livermore, California. Williams later served for three years as a research fellow at the University of Reading in the United Kingdom. He joined Rensselaer as a senior research scientist in 1999.

Williams has been a member of the American Geophysical Union since 1985 and of Sigma Xi since 1991.

Research Areas:
Williams' primary interests are the numerical and analytical modeling of tectonic problems. A significant portion of his work has included modeling of stress and deformation within the Earth's lithosphere. Examples of specific problems are elastic models of the formation of grabens and thrust faults, three-dimensional viscoelastic models of the San Andreas Fault system, and plastic-viscous models of the topography of compressive mountain belts. He also has worked on elastic models of magma chamber-induced stresses in California's Long Valley Caldera, slope stability analysis and elastic deformation modeling of the Montserrat volcano, three-dimensional viscoelastic/plastic models of the Mount Etna volcano, and three-dimensional elastic models of magma chamber-induced surface deformation of Mount Etna.

Williams has extensive experience in inverting surface geodetic data to constrain the controlling parameters of subsurface deformation mechanisms. Much of his work involves the use and development of finite element models. He has done a considerable amount of work on the finite element code TECTON, and recently added some supplementary capabilities to the Fast Lagrangian Analysis of Continua (FLAC) code.

His present work involves the inversion of surface geodetic data to obtain estimates of the stress rates and rotation pole parameters at subduction zones, as well as the inversion of interferometric and geodetic observations at Mount Etna volcano to infer magma chamber location, geometry, and pressure changes. In conjunction with his modeling efforts, Williams has been involved with the collection and processing of geodetic data, which constrains many of his models. He also has participated in several Global Positioning System (GPS) surveys and has set up and used software for the processing of InSAR and DInSAR data.

Williams currently is undertaking two different computational projects. One involves the development of a web-based modeling environment for investigating the parameters controlling surface deformation at subduction zones. This environment will provide an end-to-end solution for either forward or inverse modeling, using a finite element code to generate synthetic Green's functions. The environment consists of five primary sections, and users will be able to use any desired portion(s) of the modeling environment, combining the tools with their own methods. Users also will have the opportunity to visualize predicted results using either inversion results or a given forward model.

He also is working on the development of a complete finite element modeling environment using a parallel and scalable quasi-static finite element code. Williams is collaborating with researchers at the California Institute of Technology to place the code into the Pyre modeling framework that is under development there. The project is expected to provide additional capabilities to the web-based modeling environment, and will provide geoscientists with a very powerful modeling tool.

Selected Publications:
C.A. Williams, G. Wadge, B.S. Scheuchl, N.F. Stevens, J. Morley, J.-P. Muller, and J.B. Murray, "Model Inversion of the Deformation of a Volcano Measured by SAR Interferometry at Mt. Etna, Sicily," Journal of Geophysical Research, in preparation, (2003).

C.A. Williams and R. McCaffrey, Inversions for Stress Rate and Block Rotation in the Cascadia Subduction Zone Using a Three-Dimensional Finite Plate Model," Journal of Geophysical Research, in preparation, (2003).

N.F. Stevens, G. Wadge, and C.A. Williams, "Post Emplacement Lava Subsidence and the Accuracy of ERS InSAR Digital Elevation Models of Volcanoes, International Journal of Remote Sensing, 22, 819-828, (2001).

C.A. Williams and R. McCaffrey, "Stress Rates in the Central Cascadia Subduction Zone Inferred from an Elastic Plate Model," Geophysics Research Letters, 28, 2125-2128, (2001).

C.A. Williams and G. Wadge, "An Accurate and Efficient Technique for Including the Effects of Topography in Three-Dimensional Elastic Deformation Models with Applications to Radar Interferometry," Journal of Geophysical Research, 105, 8103-8120, (2000).

C.A. Williams and G. Wadge, "The Effects of Topography on Magma Chamber Deformation Models: Application to Mount Etna and Radar Interferometry," Geophysics Research Letters, 25, 1549-1552, (1998).

C.A. Williams, C. Connors, F.A. Dahlen, E.J. Price, and J. Suppe, "Effect of the Brittle-Ductile Transition on the Topography of Compressive Mountain Belts on Earth and Venus," Journal of Geophysical Research, 99, 19947-19974, (1994).

C.A. Williams and R.M. Richardson, "A Rheologically Layered Three-Dimensional Model of the San Andreas Fault in Central and Southern California," Journal of Geophysical Research, 96, 16597-16623, (1991).

H.J. Melosh and C.A. Williams, "Mechanics of Graben Formation in Crustal Rocks: A Finite Element Analysis," Journal of Geophysical Research, 94, 13961-13973, (1989).

C.A. Williams and R.M. Richardson, "A Nonlinear Least-Squares Inverse Analysis of Strike-Slip Faulting with Application to the San Andreas Fault," Geophysics Research Letters, 15, 1211-1214, (1988).

Contact Information:
Charles Addison Williams
Science Center 2C01B
Rensselaer Polytechnic Institute
110 Eighth Street
Troy, N.Y. 12180 USA
(518) 276-3369
willic3@rpi.edu

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