Smoothing Faults with Progressive Slip

Project Description: When earthquakes happen, faults grind rock past each other. The grinding wears down the rock face leaving a fingerprint of the mechanical effects of the earthquake. In this project we will use state-of-the-art technology to measure the degree of wear on rocks from natural and artificial faults at the micron-scale. We will figure out how different rocks are worn differently and what effect that might have on the earthquake physics.
Intern(s): Julia Avila
Mentor(s):

Emily Brodsky, University of California, Santa Cruz

Systematic Search of Triggered Non-Volcanic Tremor in California and Taiwan

Project Description: Non-volcanic tremor is a seismic signal with long durations and no clear body wave arrivals, is often found during episodic slow-slip events away from volcanoes. Tremor was first identified over a broad region in the subduction zone southwest of Japan, and was subsequently found at many places in the circum-Pacific subduction zones, and along the San Andreas fault (SAF) in central California. Non-volcanic tremor provides an exciting new tool for tracking the aseismic processes at the deep root of active fault zones, which may lead to better understandings of loading and releasing of tectonic stresses, and breakthroughs in deciphering the physics of earthquakes and faults. Recent studies have shown that non-volcanic tremor can be triggered instantaneously during the surface waves of large teleseismic events. We plan to involve an undergraduate intern to continue our global search of triggered tremor. In particular, the intern will learn how to analyze seismic data, and identify additional triggered and regular tremor in California and Taiwan. The obtained results would be useful for better understanding the necessary conditions for the occurrence of triggered tremor, and the relationship between triggered and regular tremor.
Intern(s): Amanda Fabian, Lujendra Ojha
Mentor(s):

Zhigang Peng, Georgia Institute of Technology

Incorporating and Reporting Uncertainties in Fault Slip Rates

Project Description: Estimates of fault slip rate are essential to understanding crustal deformation processes and analyzing seismic hazard. Computing slip rates requires two fundamental ingredients: estimates of the displacement along the fault of interest and the age of an offset landform or deposit. Because both of these measures contain uncertainty, slip rates are uncertain. Methods to compute and report slip rates have not been standardized, and therefore slip rate data are presented inconsistently and are frequently ambiguous; in particular, slip rate uncertainty is often insufficiently characterized. We have developed a probabilistic approach to computing and reporting intermediate- to long-term fault slip rates; we have also developed a prototype software implementation that provides standard age and displacement uncertainty models. We seek an intern to implement a web-enabled, fully-functional, GUI-based version of our fault slip rate computation prototype. Depending on the interests and skills of the intern, we envision two distinct lines of further research that may be pursued. If the intern is interested in earth sciences research, we will develop opportunities that emphasize the following:

• uncertainties in physical measurements
• how uncertainty is propagated through calculations
• importance of mathematical rigor
• techniques for computing slip rates
• importance of slip rates in determining seismic hazard
• techniques for obtaining ages

Having been exposed to these ideas, we can offer the intern the choice of a number of related activities, ranging from geological field work to laboratory sample preparation to the development of educational material related to slip rates and seismic hazard. If the intern is more interested in computer science research and software development, the internship experience will emphasize:

• programming best practices and software design principles
• presentation of scientific data in illustrations
• principles of user interface design
• database design and implementation
• importance of being able to work with someone else's code

In this case, the intern may extend the prototype implementation to include a database component whereby researchers can contribute their computations to an archive of fault slip rates; entries in this archive may then be contributed to existing fault databases.
Intern(s): Evan Reynolds
Mentor(s):

Jeremy Zechar, Columbia University
Kurt Frankel, Georgia Institute of Technology

3D Geological Model of the Crustal Structure in the Southeast Caribbean

Project Description: Active and passive source seismic data was collected from the NSF funded BOLIVAR project from 2003-2005 in the southeast Caribbean. The BOLIVAR (Broadband Onshore-offshore Lithosphere Investigation of Venezuela and the Antilles arc Region) project was a multi-disciplinary investigation to examine how island arcs, marginal basins, and oceanic plateaus become accreted to continents. Processed and interpreted seismic data from the region encompassing the Leeward Antilles island arc and the Venezuelan coast and mainland will be used to create a 3D geologic model. By investigating the location and relationship between the stratigraphic framework, faults throughout the region, and the distribution of seismicity we will be able to better understand the complex tectonic history of the Southeast Caribbean region. The 3D model will be used to visualize and assemble subsurface maps and cross sections of the southeast Caribbean Sea providing scientists a detailed visualization of an active plate boundary. This internship project involves setting up a 3D model in sophisticated commercial software, along with evaluation, reformatting, and input of seismic data. The final goal will be to provide a geologic and tectonic interpretation of this complex region. The intern will gain an appreciation for the nature and origin of crustal structure, computational tools in geoscience, and scientific data analysis.
Intern(s): Andrew Whitesides
Mentor(s):

Meghan Miller, University of Southern California
Maria Beatrice Magnani, Southern Methodist University

GPS Monitoring of San Andreas Fault 2009

Project Description: Two interns are needed to collect GPS data at various locations in the San Bernardino Mountains, Riverside/San Bernardino Valley and high desert areas. The goal of this project is to monitor elastic strain accumulation in the vicinity of the San Andreas fault. The interns will travel throughout the San Bernardino Mountains and surrounding valleys to set up GPS equipment and monitor it throughout the day. Many of the sites are remote and will require strenuous hiking, carrying the GPS equipment as well as batteries or a solar panel. Some sites will require car camping. The interns should be in good physical condition and should enjoy hiking. The intern will have access to CSUSB’s 4WD vehicle (if they have a valid CALIFORNIA drivers license), or may be reimbursed for mileage on their own vehicles. There will be a 6-day intensive data collection campaign from Friday June 26 through Wednesday July 1, during which GPS data will be collected from numerous sites simultaneously. This will be preceded by training sessions on June 24 and 25. During the remainder of July and early August the interns will collect GPS data at other sites that were not observed during the primary campaign. Interns will also learn how to interpret GPS time series from previously collected data and to conduct one-dimensional elastic modeling of GPS date for fault slip rates in southern California. Interns may rent a dormitory room at Cal State San Bernardino if they do not live within easy commuting distance of San Bernardino. Interns will pay for the cost of the room and other living expenses out of their stipend.
Intern(s): Sara Alsbury, Sarah Moreland, Joseph Salazar
Mentor(s):

Sally McGill, California State University, San Bernardino

Using LiDAR Data to Find Offsets in the Northern Death Valley-Fish Lake Valley Fault Zone

Project Description: The Northern Death Valley-Fish Lake Valley fault zone (NDV-FLVFZ) is the largest, most continuous system of the eastern California shear zone (ECSZ). Although recent studies have determined the slip rate of the fault (2.5 to ~5 mm/yr, depending on location), much less is known about the magnitude and frequency of the earthquakes that have occurred along this fault system. In my project, I used LiDAR (Light Detection and Ranging) data to document small- to intermediate-scale (meters to tens of meters) offsets along the NDV-FLVFZ, using the computer program ArcGIS. I compiled a set of 95 offsets, graded them on the basis of clarity and confidence, measured their displacements, and estimated potential errors. A histogram of these data with distance along the fault on the horizontal axis and displacement along the vertical will allow me to determine clusters of offsets based on location and amount of slip. These slip measurements provide useful estimates of the magnitude of individual ancient earthquakes on this major system. This is important to understanding what kinds of earthquakes the NDVFZ produces, which will in turn help us to better assess the likelihood of future earthquakes along this major fault.
Intern(s): Jill Hardy
Mentor(s):

James Dolan, University of Southern California

Characterizing Micro-Scale Fault Roughness Using LiDAR and Interferometery

Project Description: Faults are often considered planar, but numerous field and seismologic studies show that faults can be highly irregular, with bumps, striations, and larger-scale bends. Stress concentrates at surface asperities so that fault roughness undoubtedly plays a role in the initiation and/or arrest of earthquakes. Studies have shown that roughness of a fault at the centimeter to meter scale is directly related to total displacement along the fault, with faults surfaces generally becoming smoother with increasing displacement. Here we measure fault roughness with centimeter to 200 micron wavelengths to determine if smoothing processes continue down to the grain scale. A white-light interferometer was used to measure the topography of hand samples by emitting a broadband light source along the sample and mapping the constructive and destructive interference of the return signal to the topography. In this study, the roughness is quantified by calculating the power spectral density (PSD) along transects of the surface roughness. We measure surface roughness on several faults, as well as a surface of the solid extrusion from the 2004-2007 Mt. St. Helen’s eruption which is hypothesized to have sustained stick-slip and stably sliding frictional motion for approximately 1 km of displacement. Previous studies of larger-scale fault roughness have shown that while fault roughness decreases with displacement in the slip-parallel direction, roughness in the slip-perpendicular direction is similar on most faults (Sagy et al. 2007). Preliminary data of small-scale roughness show that roughness in the perpendicular direction is similar across some faults. These preliminary results suggest that processes controlling surface roughness at the centimeter to meter scale may differ from those at the centimeter to micron scale.
Intern(s): Alicia Muirhead
Mentor(s):

Emily Brodsky, University of California, Santa Cruz

New Products and Programs from SCEC's Communication, Education, and Outreach (CEO) Program

Project Description: In order to promote improved earthquake awareness and preparedness the SCEC CEO program and the Earthquake Country Alliance (ECA) are in the process of creating three new standards-based educational resources. The “Take on the Quake” program aims to educate several target audiences about earthquake science and preparedness through interactive activities and experiences. The “Take on the Quake” program is ideal for use in many learning environments and contexts such as museums, scouting, and in parks. The program facilitator has a choice to present “Take on the Quake” as a 20-minute overview (Express), a one-hour workshop (Explore), or as a half-day program (Experience). The “Take on the Quake” program can be used any time of the year. The “ShakeOut Curriculum” is designed for use classroom settings during the weeks leading up to, and immediately following the ShakeOut drill. This program takes consideration the time and logistical constraints in school environments. Activities for the “ShakeOut Curriculum” are designed to be flexible and are not sequence-bound. Educators can select the activities they want to use in any order and the lesson length can be easily modified. The maximum time required for any one lesson is thirty minutes. “Take on the Quake” and the “ShakeOut Curriculum” are aligned with the ECA mission by fostering a culture of earthquake and tsunami readiness in California. The materials for these programs will be available on the ECA website. The Plate Tectonics Learning Kit is an expansion and reimagining of an activity created by Professor Larry Braile at Purdue University. At the core of the kit is the USGS Dynamic Planet Poster that is cut into pieces and used as a “puzzle” activity. While extremely effective as a learning tool educators have often commented on the difficulty of knowing where to make the cuts on the map to create the puzzle. SCEC CEO team members have created a simplified version of the map with the map on one side and the cut lines for the plates and the plate names on the back. This innovation allows the facilitator to use the activity out of the box. The full Plate Tectonics Learning Kit contains the poster and an array of learning tools that provide a cross-curricular learning experience. Additionally, several of the puzzle pieces are easily misplaced and SCEC has responded to this problem by providing templates for the most easily misplaced plates (e.g. Juan de Fuca) without having to purchase a new map.
Intern(s): Warren Yamashita, Christina Gotuaco, Benjamin Dansby, Nick Rosseau
Mentor(s):

Mark Benthien, University of Southern California
Robert de Groot, University of Southern California

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Project Description:
Intern(s): Erin Schuster
Mentor(s):

Robert de Groot, University of Southern California