2011
August 2011
M5.8 Earthquake Hits Virginia on August 23, 2011 at 1:51 p.m. EDT
July 2011
GPS Division-Seismo Lab Welcomes Victor Tsai, Assistant Professor of Geophysics
Victor joined the GPS Division-Seismo Lab July 1, 2011. He is no stranger to Caltech, as he completed his undergraduate work here. He did his graduate work at Harvard University and then held a postdoctoral researcher position there. After Harvard, he worked for the U. S. Geological Survey in Colorado as a postdoctoral fellow.
Victor's research lies mainly at the intersection of seismology,
geomechanics and other disciplines like glaciology, oceanography, and
mathematical geophysics. One of his primary goals is to understand
sources of ambient seismic noise and how these sources can be used to
provide constraints on Earth structure (e.g. through ambient noise
tomography) and other physical processes (e.g. sea ice interactions
with ocean waves). He is also working to understand the
short-timescale variability of glaciers and, in particular, is
modeling rapid drainage of water in glaciers and the implications of
this drainage. In addition, Victor is interested in improving seismic
imaging techniques and geophysical time series analysis. Learn more
June 2011
Congratulations to 2011 GPS Division Graduates
Congratulations to the Geological & Planetary Sciences Division graduates! In particular, we would like to recognize the Seismological Laboratory's Geophysics doctoral graduates YoungHee Kim and Michelle Selvans. Their theses were entitled "Properties of the Subduction System in Mexico" and "Geophysical Investigations of Near-Surface Structure on the Earth and Mars" respectively.
Caltech Researchers Release First Large Observational Study of 2011 9.0 Tohoku-Oki Earthquake
PASADENA, Calif.—When the magnitude 9.0 Tohoku-Oki earthquake and resulting tsunami struck off the northeast coast of Japan on March 11, they caused widespread destruction and death. Using observations from a dense regional geodetic network (allowing measurements of earth movement to be gathered from GPS satellite data), globally distributed broadband seismographic networks, and open-ocean tsunami data, researchers have begun to construct numerous models that describe how the earth moved that day. For the full story, click here.
Click here to read article in Science Magazine: Science Express.
April/MAy 2011
Jean-Philippe Avouac, Professor of Geology and Tectonics Observatory Director
Jean-Philippe's research aims mainly at understanding better the dynamics of the earth crust and lithosphere. He therefore studies earthquakes as well as continental deformation. He has a long lasting interest in orogenic contexts (the Himalaya and Tibet in particular). More recently, he has started working on subduction zones in the Sumatra and South America context. With the help of various colleagues and collaborators, the students and postdoc working with him use seismology, geodesy, and satellite imagery to quantify deformation over the short time scale of the seismic rupture or of pre-seismic strain buildup and postseismic relaxation. 
The kinematic models derived from those studies are then used to develop dynamic models and theories of faults behavior and of lithospheric deformation. To quantify tectonic processes over the longer term time scale of thousands to millions of years, they use geomorphology, structural geology and thermobarometry in conjunction with geochronology and thermochronology. Learn more about Jean-Philippe’s research at www.gps.caltech.edu/~avouac.
February/March 2011
Thomas Heaton, Professor of Geophysics and Engineering
Tom Heaton is the Director of Caltech’s Earthquake Engineering Research Laboratory. Much of his research centers on understanding the nature of great earthquakes and their impact on the built environment. He is helping to develop a new earthquake alerting network in California that promises to provide seconds of warning that earthquake shaking is about to strike. Tom has also had a long standing interest in understanding the physics of the earthquake rupture process. In the past decade, this has centered on understanding the implications of transitions between high static fault friction and low dynamic friction. Friction laws of this type lead to dynamic chaos in the rupture process. Learn more about Tom’s research at http://heaton.caltech.edu.
January 2011
Jean-Paul Ampuero, Assistant Professor of Seismology
Jean-Paul Ampuero's research is primarily aimed at understanding the physics of earthquakes through the development of theoretical models, computational techniques and novel ways to record and image earthquake sources. One of my current research topics is the recently discovered phenomena of slow slip and non-volcanic tremor. I have developed a unifying model to explain the diversity of migration patterns of tectonic tremor, their scaling properties and their relation to slow slip transients. I am also involved in the search for spontaneous tectonic tremors in southern California, with a current focus on the San Jacinto fault. My team is involved in seismological experiments in South America. We were among the first to deploy broad band seismometers in Chile following the 2010 M8.8 Maule earthquake. Its largest aftershock, the 2011 M7.1 Araucania earthquake, was caught by our network clustered around the Arauco peninsula. Our next adventure will take us to southern Peru in search of tectonic tremors. Learn more
2010
December 2010
Seismo Lab Students Present at the AGU Fall 2010 Meeting
December 13-17, Seismo Lab students will present their research at the American Geophysical Union (AGU) annual Fall 2010 meeting. They will report their findings on a range of topics, reflecting the diversity of studies undertaken in the Seismo Lab and the collaborative approach to addressing research questions.
Dan J. Bower will present a new geodynamic and mineral physics model for an ultra-low velocity zone (ULVZ). ULVZs are patches of much reduced seismic velocities at the core-mantle boundary that were first discovered at Caltech in the 1990s by students working with Prof. Don Helmberger.
The AGU annual Fall meeting, held in San Francisco, is the largest gathering of Earth scientists in the World and the premier conference for geophysics. Each year Seismo Lab students, post-docs and faculty showcase their research through invited talks, oral presentations, and poster sessions.
Learn more about Dan J. Bower's research
Learn about other research in the Seismo Lab
November 2010
Don Helmberger, Professor of Geophysics
Don Helmberger's research concentrates on modeling seismograms using both numerical and analytical methods. Because seismograms contain information about earthquake sources and earth structure, they both must be addressed in modeling. Thus, we study source complexity ranging from .2s to 50s involving events ranging from Mw= 2 to 9. Using such sources, we can examine the detailed structures in the earth from shallow features beneath Yellowstone to Superplumes near the Core-Mantle Boundary. Learn more
OcTOBER 2010
Jennifer Jackson, Assistant Professor of Mineral Physics
Jennifer's research focuses on combining experimental results with geophysical methods to better understand planetary interiors. By combining a suite of spectroscopic methods, primarily at advanced radiation sources, she determines the elastic, vibrational, and chemical properties of candidate planetary materials under extreme conditions of pressure and temperature. Through collaborations with Seismo Lab colleagues, she integrates the most recent mineral physics results with seismic observations and geodynamic modeling to gain a multi-dimensional understanding of the deepest parts of Earth's interior. Learn more
September 2010
Mark Simons, Professor of Geophysics
Mark’s research focuses on combining geodetic observations with geodynamic models to understand the mechanics of the lithosphere and upper mantle. Currently, he primarily focuses on seismic, aseismic, and volcanic processes as constrained by interferometric radar and GPS data. In a related effort, he is working on ways to incorporate modern geodetic data into rapid earthquake models for assessment and response applications. Mark also studies large scale tectonic processes on the terrestrial planets using gravity and topography data. Recent projects focus on the use of Bayesian approaches to estimating kinematic fault models, internally consistent frictional models of fault slip in subduction zones, automatic aseismic transient detection systems for GPS and InSAR time series using multi-scale approaches, and models for recent large earthquakes in Haiti, Chile, and Baja California. Learn more
August 2010
The Salton Seismic Imaging Project
The Salton Seismic Imaging Project is a large-scale active seismic survey that will take place in Feb. 2011 to study earthquake hazards and rifting processes in southeastern California (Imperial and Coachella Valleys) and northwestern Mexico (Mexicali Valley). These valleys are formed by right-lateral strike-slip faulting, extension, and magmatic intrusion between the Pacific plate (on the west) and the North America plate (on the east). Because the southern San Andreas fault ends in this region, its slip is transferred to a number of other active faults that bound the mountain ranges and valleys, and extend under water into the Gulf of California. The project will create images of subsurface geology to investigate the different plate tectonic processes and the earthquake hazards they cause. We will image the deep structures in the basins and the geometry and interconnectivity of the active faults. The images will determine the subsurface geometry of the southern San Andreas fault, and the thickness and physical properties of the basin sediments - all of which are critical in order to simulate the expected shaking from a major earthquake. The survey will involve about 3000 seismometers deployed for 3 weeks, and a set of sound waves generated from boreholes a few hundred feet below the surface. Learn more
July 2010
Swami Krishnan, Assistant Professor Earthquake Engineering Researcher
Swaminathan Krishnan is an Assistant Professor of Civil Engineering and Geophysics at Caltech and a structural engineer specializing in earthquake engineering. Professor Krishnan leads the earthquake engineering simulation group (http://krishnan.caltech.edu/) which pursues fundamental research in earthquake engineering with applications to end-to-end simulation of earthquakes and structural response using high-performance computing. End-to-end simulations consist of holistically simulating the earthquake process, starting with fault rupture, generation and propagation of seismic waves to a site(s) of interest, and shaking of the top-soil layer, simulating the structural response including soil-structure interaction, and estimating the losses due to damage, and the opportunity cost due to interruption of structure usage. Learn more
