2010 SCEC Intern Research Lecture Series

Bio: I am Magali Barba, also known as Maggie, a 20 year-old Chicana junior at the University of California at Berkeley. Growing up in the tectonically active area of the Los Angeles County, just a few meters from the Newport-Inglewood fault, I was fascinated by the forces that caused earthquakes and shaped my surrounding terrain. My interest in earth science motivated me to pursue a degree in geophysics. To learn more about seismology, I interned at the Southern California Earthquake Center. Last summer as a USEIT intern, I identified potential earthquake swarms in the Bombay Beach area by analyzing relocated earthquake catalogs for Southern California on Microsoft Excel. I then used SCEC-VDO to animate the identified Bombay Beach Swarms’ progression towards the southern-most segment of the San Andreas Fault. This summer I am interning at the California Institute of Technology's Seismological Laboratory through the SCEC SURE program. Under Maren Boese and Egill Hauksson, I am contributing to the development and optimization of the CISN ShakeAlert, a prototype earthquake early warning system for California. I hope to continue research in earthquake early warning during my remaining time as undergraduate student and into graduate school.

Abstract:

California has 99.7% chance of experiencing an earthquake of magnitude 6.7 or greater and a 50% chance of a magnitude 7.5 or greater within the next 30 years. The earthquake and aftershocks are expected to cause severe destruction and injuries, however, an earthquake early warning system (EEWS) may help prevent and mitigate the damage. Over the past four years the California Integrated Seismic Network (CISN) has tested the real-time performance of three algorithms for EEW in California. In the next two years, the three semi-parallel processing threads will be merged to a single integrated system, called CISN ShakeAlert. The Tauc-Pd On-site warning algorithm, one of the algorithms implemented at Caltech, provided almost 40 seconds of warning time to Caltech during the recent San Jacinto earthquake on July 07, 2010. In addition to the testing of CISN ShakeAlert on real-time earthquakes, a tool to demonstrate and assess its potential performance during large earthquakes using several scenarios is under development. In Geoffrey Ely's Elsinore Fault- S1, a Mw 7.75 earthquake scenario, Caltech has the potential to receive 60 seconds of warning time. During the next few weeks, magnitude and intensity predictions will be integrated into the demonstration tool.

Magali is currently a junior at the University of California at Berkeley. In 2009 she was a USEIT intern. She is currently a SCEC SURE intern working under Maren Boese and Egill Hauksson at the California Institute of Technology's Seismological Laboratory.To learn more about the SCEC Internship Program visit: www.scec.org/internships.

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Bio: I am Christiann Boutwell- born and raised in South Carolina. I received my undergraduate degree in Geology at the University of South Carolina (known as USC on the east coast). I was a SURE intern in 2008 where my interest in earthquakes and seismology blossomed after my experience of the Chino Hills earthquake. I am currently a doctoral candidate at the University of Southern California (USC) under the advisement of Dr. Thomas Jordan. I chose USC because of the opportunities to participate in seismological research. My current research involves earthquake catalog and aftershock distribution analyses.

Abstract:

Over 60 million years ago, the Rocky Mountains emerged from a shallow sea of a previously stable continent. When this occurred, old crystalline rocks were thrust upward causing the overlying sedimentary layers to bend into large arches. To understand how these mountains were created so far away from plate tectonic boundaries, NSF-EarthScope funded a three-year investigation of the Rocky Mountain Bighorn Arch in northern Wyoming and southern Montana. This investigation combines geological surface geometries and kinematic indicators with geophysical imaging of 3D crustal and upper mantle geometries from active and passive seismic experiments. I recently returned from helping out with the active part of the seismic experiment which involved deploying instruments that record seismic waves from several large explosions. The purpose of my presentation is to give you a glimpse of how earth scientists collect data and how/why they use this data for their research and understanding Earth.

Christiann is currently a graduate student in the geophysics Ph.D. program at USC. She completed her B.S. in geology at the University of South Carolina. In 2008 she was a SCEC SURE intern working with Peter Powers at USC. During the Fall and Spring of the 08-09 academic year she was a SCEC ACCESS-U intern working with Dr. Tom Jordan and is currently a SCEC ACCESS – G intern working with Dr. Tom Jordan at USC. To learn more about the SCEC Internship Program visit: www.scec.org/internships.

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Bio: I am Mark Swift, a geology student at California State University, San Bernardino (CSUSB). I grew up in Flamingo Heights, a small town right next to Landers, California. I experienced many foreshocks to the Landers earthquake, and although I was out of town when the M7.3 earthquake struck Landers in 1992, I witnessed the destruction, disruption of normal life an earthquake can cause, and the awesome power of earthquakes. After the Lander’s earthquake I watched seismologists on TV and saw geologists studying the earthquake ruptures in trenches near my house. The earthquake ruptured to the surface about a dozen yards away from my house and went underneath our neighbor’s house. All this excitement got me very interested in earthquakes. Last year, for my senior project, I used the data collected by SCEC interns to model slip rates of the major strike-slip faults in the Southern California area. I used both SCEC’s and CSUSB’s GPS velocity data

Abstract:

Living in Southern California, we need seismic hazard analysis for building codes, planning purposes and insurance purposes. I wanted to find slip rates of the local Southern California faults, so that the slip rates could be used for seismic hazard analysis. During the summer of 2009, under the direction of Dr. Sally McGill, SCEC interns and I collected GPS data from benchmarks within and surrounding the San Bernardino mountains in Southern California. I supplemented SCEC’s robust Crustal Motion Model 4 (CMM4) with CSUSB’s GPS position data collected from 2002-2009 in the remote and difficult to reach San Bernardino mountain sites, which SCEC’s CMM4 didn’t cover. From the position vs. time data, I calculated site velocities parallel to the plate boundary. The site velocities ranged from 8.8 mm/yr southeast to 44.7 mm/yr northwest relative to the North America plate. I systematically tested 735,000 combinations of slip rates out of 3,000,000 original permutations considered. The GPS velocities were used to constrain slip rates on the eleven major strike-slip faults (Palos Verdes fault, Newport-Inglewood fault zone, Elsinore fault, San Jacinto fault, San Andreas fault, Helendale fault, Lenwood fault, West Calico fault, Pisgah fault and Ludlow fault), that form the plate boundary in Southern California. I assumed a two-dimensional elastic half-space model. Specific locking depths were used, as suggested by the maximum depth of earthquake hypocenters, which ranged from 10.5 to 19 km. After testing 735,000 models, 5,182 were found to reasonably fit the GPS velocities. These models have slip rates ranging from 0 to 14 mm/yr for the San Andreas fault, from 4 to 22 mm/yr for the San Jacinto fault, and from 15 to 18 mm/yr for the combination of faults making up the eastern California shear zone (Helendale fault, Lenwood fault, West Calico fault, Pisgah fault and Ludlow fault). My study shows that the San Jacinto fault and the eastern California shear zone are the portions of the plate boundary that may be accumulating elastic strain the fastest, with the San Andreas fault playing a lesser role in the Big Bend area.

Bio: I am from Menlo Park, California, an in-between place about 40 minutes south of San Francisco. I am majoring in Earth Sciences and minoring in physics at USC and will be entering my fifth year there in the fall. Over the next few years, I intend to pursue a PhD in seismology while taking classes in civil engineering and learning Hindi and Farsi; after that I would like to work in south Asia educating people about seismic hazards. If it becomes safe to do so, I am particularly interested in working in Tehran, both because it is one of the most seismically at-risk cities in the world and because it would present a unique opportunity to build bridges between America and Iran. Other possible paths include working in the Pacific Northwest to try and get literally every person and building prepared for a future earthquake on the Cascadia subduction zone, or working in other at-risk places around the world such as Algeria, China, or South America.

Abstract:

Using the SCEC CyberShake project’s variable-slip models for eleven hypothetical M>7 southern California earthquakes, we calculate the Coulomb stress changes that each earthquake imparts to major local faults. Strong stress interactions are found between the San Andreas and subparallel right-lateral faults, the northward-dipping thrust faults under the Los Angeles basin, and the left-lateral Garlock Fault. M>7 earthquakes rupturing sections of the southern San Andreas fault decrease Coulomb stress on the San Jacinto and Elsinore faults and impart localized Coulomb stress increases and decreases to the Garlock, San Cayetano, Puente Hills and Sierra Madre faults. M>7 earthquakes rupturing the San Jacinto, Elsinore, Newport-Inglewood and Palos Verdes faults decrease Coulomb stress on parallel right-lateral faults. A M=7.35 earthquake on the San Cayetano fault decreases stress on the Garlock fault and imparts stress increases and decreases to nearby sections of the San Andreas. A M=7.15 earthquake on the Puente Hills fault increases stress on the San Andreas and San Jacinto faults, decreases stress on the Sierra Madre fault and imparts localized stress increases and decreases to the Newport-Inglewood and Palos Verdes faults. A M=7.25 shock on the Sierra Madre fault increases stress on the San Andreas and decreases stress on the Puente Hills fault. These are the most robust findings derived from calculations using two alternate variable-slip models for each of the eleven earthquakes. We plan to use several models for each earthquake in order to assess the effect that variations in the distribution of slip have on the magnitudes of these stress interactions.