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current projects

The Alaska Earthquake Center - AEIC
As the State Seismologist for Alaska I help direct the activities of the Alaska Earthquake Information Center. AEIC is charged with collecting, archiving and interpreting earthquake activity across the state of Alaska. Four-fifths of the seismicity in the U.S. occurs in Alaska. AEIC processes ~30,000 earthquakes per year. Pursuant to Alaska statute 14.40.075, the office of the State Seismologist nurtures science that impacts earthquake and volcano hazard assessments and collaborates to inform the state of earthquake and volcanic risks. The Alaska Earthquake Information Center is located on the campus of the University of Alaska Fairbanks within the Geophysical Institute.

The Alaska Volcano Observatory - AVO
I have been affiliated with the Alaska Volcano Observatory for many years. My group carries out rapid analysis of seismic swarms, volcanic tremor and explosive seismic and infrasound events. We supplement visual monitoring with the development of novel detection and alarm systems. Our emphasis is on products and research that bring to AVO the capabilities of the Seismology Lab. AVO is a partnership between the UAF Geophysical Institute, the Alaska Division of Geological and Geophysical Surveys and the U.S. Geological Survey.

Volcanic earthquake swarms - SWARMS
This project is assessing earthquake swarms at volcanoes worldwide to identify those characteristics that most often precede eruptions. This has been a primary pursuit of volcano seismology for decades. This project is unique in that we are working from original seismic waveforms from numerous volcanoes. By using original data we are producing standardized measures that allow direct comparison between swarms. The goal is to improve eruption forecasting by producing statistically valid characterizations of earthquake swarms. (NSF award #1044930)

Seismic investigations at Yahtse glacier - YAHTSE
Glaciers are a constant source of seismic signals in Alaska. As ice deforms and cravasses, smal "ice quakes" can occur at rates of tens per minute. One objective of this project is to refine how the continuous seismic record can be used to infer the motion of the glacier. Glaciers that terminate in the ocean produce additional signals from iceberg calving. These events are large enough that have been recognized for decades in the regional seismic record. The defense instrumentation at Yahtse glacier is helping us tie the regionally observed glacier seismograms to specific mechanics of iceberg calving. (NSF award #0810313)

Magma intrusion beneath Andean supervolcanoes - PLUTONS
The PLUTONS project is an ambitious experiment to understand the mechanics of deep magma injection in Earth's crust. Funded by NSF Continental Dynamics, this UAF-led project partners several universities to carry out a large scale campaign at two large caldera volcanoes in the Bolivian and Chilean Andes with known inflation. Field campaigns in seismology, geodesy, petrology and magnetotellurics are being synthesized with thermomechanical modeling efforts to produce a vision of how new crust is built in continental arcs through the intrusion of magmatic plutons. (NSF award #0909254)

Partnership in volcanological research and education - PIRE
This project comprises a multi-disciplinary field campaign focused at Bezymianny volcano, Kamchatka. Bezymianny is the type example of sector collapse volcanism - a process not widely recognized in the U.S. until the 1980 eruption of Mt. St. Helens. Bezymianny, which had a strikingly similar eruption in 1956, is being studied with combined seismology, petrology and geodesy to learn how sector collapse systems respond and rebuild in the decades following eruption. Funded by a unique NSF program, the PIRE project has introduced dozens of graduate students to the benefits (and challenges) of internationally collaborative science. (NSF award #0530278)

Matlab toolboxes for seismology - GISMO
The GISMO project is an effort to coordinate Matlab-based software efforts in research seismology. The code base is founded on a core set of tools written in the UAF Seismology Lab, and distributed openly through Google Code. The scope of the toolbox broadly includes tools for manipulating seismic waveforms and, increasingly, earthquake catalog data. Users are encouraged to submit mature tools back into a "contributed" section of the code repository. An accompanying user group has roughly 100 users.

Common workspace for Alaska earthquakes - CWAKE
CWAKE is an openly-distributed "workspace" for research using earthquake data from the Alaska Volcano Observatory. Configured largely by network seismologist Glenn Thompson, CWAKE includes a set of velocity models and parameter files to customize the BRTT Antelope processing software for Alaska volcano data. CWAKE supplements AVO's in-house processing stream with a platform more amenable to research seismology. CWAKE can be used with databases from the AVO earthquake catalog. The full power of CWAKE is realized when accompanied by waveform data requested from AVO or downloaded from the IRIS Data Management Center.

education projects

The Alaska Summer research Academy - ASRA
ASRA is a UAF summer program which draws high school-aged students from across the country for two weeks of real world research experience. The Earthquakes in Denali module introduces a small group of motivated students to rewards and challenges of geophysical field work. We spend several days of field camp at Denali National Park, studying Alaska tectonics and deploying an array of seismic stations to record the numerous daily earthquakes in the area. Back in the Seismology Lab, students investigate their data and self-publish their observations on the web. Student-authored ASRA websites: 2006, 2007, 2009, 2010.
Introduction to Geophysics (New Mexico State University)
Geophysics 330/450 is a joint undergraduate and graduate Introduction to Geophysics course at New Mexico State University. I have not taught this course since leaving NMSU. The content is no different than similar courses that emphasize a strong conceptual understanding. However the worksheets that accompany some of the graphical homework and exam problem sets have proven popular (see homework 3, 11, 13, 14; Exams 1, 3). Original Illustrator files and solutions available on request.

past projects

Colima volcano deep seismic experiment - CODEX
The center piece of this project was a 20 station seismic array centered on Colima volcano, Mexico with an unusual aperture wide enough to determine properties of the lower crust. A combination of seismic tomography and local seismicity are paired with published petrology. Together they help constrain the processes through which basaltic magmas, formed deep in the subduction zone, evolve into the more explosive andesitic volcanics that erupt in continental arcs. (NSF award #0439882)

Triggered seismicity following the 2004 Sumatra earthquake
Following the 2004 Sumatra earthquake, small earthquakes were triggered beneath Mt. Wrangell volcano, Alaska. While triggering is common after such large earthquakes, this was the first documented case of earthquakes being triggered with the same periodicity as the teleseismic surface waves. This project explores mechanisms for these quakes in the context of the surface wave strains. Complete dataset is available for download.

Rio Grande Rift Seismic Transect - RISTRA (alt.)
The RISTRA project is based on an exceptional 1000-km linear seismic array across the southwest U.S. The transect spanned the Great Plains, Rio Grande Rift and the Colorado Plateau. Surface wave tomography, body wave tomography and receiver functions demonstrated the rifting mechanism and the lithospheric support for the Colorado Plateau. The dataset was also the test bed for a joint inversion technique for teleseismic body and surface wave.

Deep structure of Axial Volcano
Axial volcano sits astride the Juan de Fuca Ridge, 300 km off the Washington-Oregon coast. We used marine refraction techniques and ocean bottom seismometers to image the magmatic system of Axial. In addition to documenting hte approximate size of the magma reservoir, this project mapped considerable topography on the base of the crust. This topography, combined with knowledge of the spreading center, demonstrated the focused delivery of magma from the underlying hotspot. This project comprised by Ph.D. thesis.

Seismic structure of north and south Tibet
Surface wave velocities calculated across north and south Tibet demonstrate considerable differences. A low velocity zone in the mid-crust of southern tibet is though to result from melt caused by heat and water from the inter-plate shear zone. Fast mantle velocities in southern tibet reflect the presence of the Indian plate lithosphere, while northern Tibet exhibits low deep crustal velocities caused by high heat from the mantle.

Travel time calibration for Asia IMS stations
This investigation was part of a larger project to improve and validate earthquake locations in Asia. I investigated the influence of different regional velocities of seismic wave propagation across the continent. This investigation compared different methods of meshing regional travel time information and/or velocity models.

The Long Island Sound Project
This was a proof-of-concept project to demonstrate the feasibility of using seismic refraction techniques to monitor ground water levels. Conducted in beach sand, we collected seismic profiles every half hour over a full tidal cycle. Differences in P-wave travel times and surface wave velocities were combined with numerical models of water table oscillation. This study demonstrated that seismic refraction is a viable approach to capturing certain time-lapsed phenomenon in the near surface and, when boundary conditions are known, can be used to measure hydraulic properties of rock.

Structure of north rift zone, Iceland
An active source project is northern Iceland provided seismic velocity structures of the northern rift zone crust and uppermost mantle. We imaged frozen intrusive bodies in the crust and a lower velocity structure beneath Krafla volcano. This project is notable for the clarity of the multiple phase arrivals including P, PmP, Pn, PP, PPP, S and SmS.