Studies currently under way include the local San Gabriel mountains, the epicentral region of the January 1994 Northridge earthquake and other regions of interest near the San Andreas fault. These measurements are being carried out in collaboration with other institutions including JPL and Caltech. The Claremont Colleges campus also serves as host for one of a network of continuously-recording GPS sites. When completed, this network will provide complete high-resolution geodetic coverage of the Los Angeles basin, and the resulting data will contribute to improved earthquake hazard assessment as well as improved understanding of the basic mechanics and processes of tectonic deformation.
The results obtained to date from the local East San Gabriel GPS project shows
interesting motions, and some suggestion of strain accumulation associated with the
Cucamonga fault. This region may require study at higher spatial resolution than is
possible with the current sparse network. A possible research project would involve the establishment and survey of a dense profile of GPS stations crossing the Cucamonga fault with a spacing of a couple of kilometers or less. Such measurements might prove extremely valuable in
filling in the details of deformation in this active region.
| Link to GPS
Activities Page |
Seismology: The Edwards Geophysics Laboratory contains six recording seismometers, acquiring both short-period (1.0 Hz) and long-period (0.05 Hz) data around the clock. While based on instruments of early vintage, the lab is well on its way to being upgraded to a modern digital data acquisition-based facility.
Students have recently completed calibrations that will permit the use these digital data in quantitative research projects. There are abundant opportunities to apply Fourier-based signal processing and filtering techniques to these results, and much software development is needed.
A new research project which I would very much like to get started in the coming year will involve the replacement of our (somewhat antiquated) seismometers with new broadband digital instruments. It should be possible for us to construct a set of instruments that use force-feedback techniques to achieve flat frequency response across the entire seismic frequency range, and sensitivity limited by Brownian motion. The improvement over our current instruments may be as much as two orders of magnitude. This project is ideal for students with a strong interest in practical fabrication and design, as it will involve much original machine shop and electronics work.
Apart from design and fabrication of seismic instruments, applications of this work can vary, according to the students' interest.
Classical geophysical investigations may examine such topics as
wave propagation from distant earthquakes, detailed analysis of ground
motion in local events or spectral studies. Research on the boundary with
earthquake engineering may be possible by combining ground motion determination
with building response, as studied by Prof. Duron in Engineering. Finally,
since the seismo lab is an educational facility, there is interest in making
its products widely available to the community through the Web. Work in this
area could include development of algorithms and automated procedures for
earthquake detection and quantification.
| Link to Seismo Lab
Page |
Electromagnetic Effects and Earthquakes: Over the last decade, researchers in various parts of the world have reported and studied possible electromagnetic effects preceding and/or accompanying moderate and large earthquakes. The mechanisms of these effects are not well understood, and their general applicability as a possibly useful seismic precursor is being debated. Current prevailing opinions in the geophysical community are generally skeptical, but the potential for investigations in this area is interesting.
A student research project has been started here (at the Bernard Biological Field Station north of Foothill Blvd.) to examine this phenomenon. Approximately 500 meter electric dipole antennas have been installed with the aim of measuring the time dependent behavior of passive and generated electric fields, and their correlation with local seismicity. The project is just barely underway, and requires significant work in background research, computer setup and data analysis strategies.
Computer Inversion Techniques for Fault Mechanics: In addition to the finite element simulation studies described above, there is a need to be able to invert experimental data sets (such as those obtained in our GPS studies) for the parameters of active faults. A variety of possible approaches exist, depending upon the nature of the problem and how well constrained it is. Currently, senior physics major Wendy Panero is working on application of the "simulated annealing" algorithm to the solution of these problems.
Chaos and Earthquakes: Simple models of the recurrence of earthquakes tend to produce "chaotic" solutions. Self-organized critical systems appear in many ways to provide useful analogs of the earthquake process. Research of the literature and design of computer models may produce some original contributions in this area.
Eclipse "Shadow Bands": In 1992-93, S. Taylor worked with me on the problem of modelling and understanding the unusual "shadow band" phenomenon sometimes observed during partial phases of a solar eclipse. The phenomenon appears to involve atmospheric turbulence and scintillation. The work was partially completed but could be continued and lead to very interesting insights.