The work with my advisors George Zandt & Susan Beck uses local and teleseismic earthquakes to characterize the tectonic processes which influence the structure and evolution of continental lithosphere and sub-continental asthenosphere. This is mostly achieved using receiver function analysis and shear-wave splitting. My research focuses on two former continental arcs, the Coast Mountains and Sierra Nevada Batholiths. Additionally, George and I are interested in using observations of seismic anisotropy to place constraints on the development and distribution of shear-derived fabric in the tectosphere of the North American Cordillera.
PRESENT WORK:
Sierra Nevada EarthScope Project (SNEP)
~100 broadband seismic stations, 2+ years, and enough site permitting issues for a life-time: SNEP. After assembling an spectacularly high-quality dataset of broadband waveforms sampling nearly the entire length of the Sierra Nevada Batholith, our goal is to characterize the ongoing delamination of a dense, eclogitic (arc-logitic?) residue from beneath the Central Sierra Nevada. Addtionally, we seek to place constraints on the extent of delamination, if any, beneath the Northern Sierra Nevada. You may have seen a slightly more polished version of the figure below in the IRIS Long Range Plan for Seismology. Earthquake locations courtesy of Owen Hurd (formerly Arizona, now Stanford). Further information related to this figure is available upon request, as I wouldn't want to spoil the results of this publication!
Coast Mountains Batholith Seismic Transects (COMBAT: Batholiths Continental Dynamics Project)
In conjunction with Ken Dueker (Wyoming) and his students, Arizona helped deploy 46 broadband seismometers in two transects across west-central British Columbia from May 2005 to September 2006. Our goal is to evaluate the seismic character of the lithosphere beneath various accreted exotic terranes and Coast Mountains Batholith, which dominate the geology of western British Columbia. This study focuses on problems related to understanding large igneous provinces and determining the processes that are responsible for the genesis and recycling of continental crust. My role in this study has been to conduct teleseismic shear-wave splitting measurements to constrain deformation in the subcontinental mantle. The preliminary results do not fit within current models for the state of the mantle beneath this region of the North American Cordillera.
PAST PROJECTS:
Consortium for Arizona Reconnaissance Seismic Experiment (COARSE)
The Universities of Arizona and Arizona State maintained an array of 10 broadband seismometers across Southeast and Central Arizona to evaluate changes in the character of the crust and upper mantle across the Basin and Range and Colorado Plateau.
Earth and Planetary Science Letters Article
Episodic Tremor and Slip and Subduction Zone Structure (ETS)
Ten years of Pacific Northwest Seismic Network broadband recordings, along with newly acquired data from a dense array which recorded from August to November 2005, are used characterize the receiver function response of the subducting slab and mantle hydrated zone during the periodic episodes of non-volcanic tremor and geodetic slip within the Juan de Fuca subduction zone. Do receiver function attributes change during ETS episodes? If so, is the cause noise or tectonic? Presenting this poster felt like I voluntarily stood in front of a firing squad, but the data looks compelling and we just need more of it. Then the EarthScope Transportable Array came along. Remember, part of science is challenging conventional notion. At some point I plan to continue this work.
South Carolina Earth Physics Project (SCEPP)
I worked with Tom Owens addressing the issue of network clock accuracy on the SCEPP Seismic Network. During the NTP study I familiarized myself with UNIX and TCL and ultimately published my first scientific paper, in no small part to Tom's help. It's a very modest work!
SCEPP Seismological Research Letters Article
Summer of Applied Geophysical Experience (SAGE)
The SAGE Program runs a geophysics field research program each summer near Santa Fe, NM. Our study focused on a seismic, gravity, and electrical investigation in the Santo Domingo Basin between Santa Fe and Albuquerque. At the end of SAGE, I processed, interpreted, and presented magnetotelluric data that helped develop a 1-D geoelectric cross-section of the survey area. This cross-section was subsequently used by the Cochiti Indians to evaluate water reservoir potential on their reservation.