Research

South America
My graduate work has been centered around studying
the South American subduction zone of Chile and Argentina
from a seismic perspective. I was involved in the
deployment of the Passcal CHile ARgentina Geophysical
Experiment from 2000-2002, archiving the data, locating
events, and analyzing waveform data for seismic anisotropy.
The subduction zone in our area of study (from 30-36
degrees south) is especially exciting because it contains
an area of flat subduction. Our project was centered
over the transition from this flat-slab zone in the north
to a more normally-dipping zone to the south, and many
of our analyses have been aimed at understanding both
the mechanism of flat subduction and its effects on
the tectonics of the area.

Shear-Wave Splitting Studies
Teleseismic
Local Events
View results of other studies with this data set at the
Chile Argentina Geophysical Experiment Web Site

My advisor George Zandt at ELBO, a station in the high
Andes of Chile
A view out the car window of a basement-cored uplift of the
Sierras Pampeanas.

Other Photos from the CHARGE Deployment

Publications and Recent Abstracts
INVITED Anderson, M. L., Zandt, G., 2004, Multiple layers of anisotropy in the Chile-Argentina subduction zone, South
America: Eos Trans. AGU, 85 (47), Fall Meet. Suppl., Abstract T21B-0517, (Page Size Poster 776 KB).
Anderson, M. L., Zandt, G., Triep, E., Fouch, M., Beck, S., 2004, Anisotropy and mantle flow in the Chile-Argentina
subduction zone from shear wave splitting analysis: Geophysical Research Letters, 31, L23608,
doi:10.1029/2004GL020906, (316 KB).
Anderson, M. L., Zandt, G., Triep, E., 2004, Mantle flow in the Chile-Argentina flat slab subduction zone from
seismic anisotropy: 16th Annual IRIS Workshop, (Page Size Poster 1.1 MB).

San Bernardino
Despite decades of research devoted to the San Andreas
fault system and related tectonic problems, there remain
profound questions about its development through time.
These questions range from basic questions about the
structure of the crust and mantle within the fault zone
and total offset on individual faults, to questions about
the dynamics of fault activation and fault interactions
along segments exhibiting complex fault networks. Prior
to my graduate work I was an intern at the USGS in Menlo
Park, CA where I concentrated on using gravity data to map
the structure of the San Bernardino strike-slip basin
centered of the San Jacinto fault, a strand of the San
Andreas fault system in southern California. By
supplementing the gravity data with aeromagnetic data, I
built a new high-resolution structural model of the basin
and a kinematic model of its development. Previous models
utilized the San Bernardino basin as a center of transfer
of strike-slip offset from the San Jacinto fault to the
adjacent San Andreas fault. This model is not supported
by my data, and I suggest that most right-slip along the
San Jacinto fault connects with the San Andreas further
north along its Mojave segment.

Introduction to the San Bernardino Basin
Initial documentation of this study excerpted from my
1999 AGU poster on the basin.

Publications
Anderson, M., Matti, J., Jachens, R., 2004, Structural model of the San Bernardino Basin, California from
analysis of gravity, aeromagnetic, and seismicity data: Journal of Geophysical Research, v. 109, B04404,
(13.3 MB).
Stephenson, W. J., Odum, J. K., Williams, R. A., Anderson, M. L., 2002, Delineation of faulting and basin
geometry beneath urbanized San Bernardino Valley, California, from seismic reflection and gravity data:
Bulletin of the Seismological Society of America, v. 96, no. 6, p. 2504-2520, (4.8 MB).
Anderson, M. L., Roberts, C. W., Jachens, R. C., 2000, Principal facts for gravity stations in the vicinity
of San Bernardino, southern California: U.S. Geological Survey Open-File Report 00-193
(URL http://geopubs.wr.usgs.gov/open-file/of00-193/).

Joshua Tree Integrative Geodetic Network

GPS in Joshua Tree Nat'l Park
Newer projects for me in Southern California center
around interactions between the San Jacinto, San
Andreas, and Eastern California shear zones. This
works stems from collaboration with Rick Bennett,
a geodesist at U of A. We have obtained permits and
field work commenced September, 2005 to install
several GPS sites in Joshua Tree National Park in
order to monitor present strike-slip deformation and
perhaps uplift in the southernmost section of the
Eastern California shear zone. For an overview of
the JOIGN project, please visit our webpage.

Recent Abstracts
Anderson, M., Bennett, R., Matti, J., 2004, New constraints on models for time-variable displacement
rates on the San Jacinto fault zone, southern California: AGU, 85 (47), Fall Meet. Suppl., Abstract
G11A-0769, (Page Size Poster 592 KB).

Wyoming
As an undergraduate, I studied a fluvial conglomerate
deposit exposed in the Clark's Fork of the Yellowstone
River Valley in Wyoming. The deposit has long interested
structural geologists because it is cut by the Heart
Mountain fault. For my undergraduate thesis, I documented
the stratigraphy and interpreted it as a catastropic flow
deposit of remobilized river bed sediment. It was deposited
in a paleovalley incised into the flanks of the Beartooth
uplift in the early Eocene.

The Crandall Conglomerate

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Last Updated: 01/2005