GPS Monitoring of San Andreas Fault

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): Christina Velasquez
Mentor(s):

Sally McGill, California State University, San Bernardino

A GPS Resurvey of the Anza Gap Region, California: Preparation for an Earthquake on the San Jacinto Fault

Project Description: The San Jacinto fault is considered one of the most dangerous structures in California, with the highest probability of failing in a magnitude >6 earthquake. In the event of such an earthquake, critical information about the stress release and frictional state of the fault must be collected by measuring the displacement of the ground in the hours to days that follow. Such measurements can be made using GPS receivers installed above survey benchmarks; knowledge of the locations and positions of such benchmarks before the earthquake is therefore essential. We propose to conduct a GPS resurvey of the survey benchmarks surrounding the San Jacinto valley and Anza segments of the San Jacinto fault. All of the sites are located within a short driving distance of the host institution, UC Riverside; many have not been surveyed for 10 years or more. Through assessment of simple computer models, the intern will assess the relative importance of the various benchmark sites for constraining earthquake slip or afterslip on segments of the San Jacinto fault, and so develop a prioritization strategy for post-earthquake response. We will also test the potential improvement to our models that may be obtained by adding additional sites, such as existing benchmarks that have not previously been used for GPS surveys, and if necessary, include them in the survey.
Intern(s): Alexandra Millar
Mentor(s):

Gareth Funning, University of California, Riverside

Community Velocity Model for the New Madrid Seismic Zone

Project Description: In 1811-1812, a series of three major earthquakes struck the Central United States in the New Madrid Seismic Zone. Having magnitudes near 7.5 and being located within the relatively stable interior of the North American Continent, these events produced widespread strong shaking. If these events were to occur today, there would be substantial devastation. To better understand this threat and in preparation for the upcoming bicentennial, the US Geological Survey is planning to produce sophisticated numerical simulations of earthquake rupture and seismic wave propagation due to a repeat of these events. To kick off this effort, the USGS will mentor an intern in the development and construction of a community seismic velocity model for use in these numerical simulations. The intern will have the opportunity to learn about seismic hazards and risk, numerical simulation of seismic wave propagation and various methods for deriving subsurface velocities. The intern will be expected to locate and bring together in a standard format existing studies of seismic velocity in the region. He/she should have good communication and computer skills and a basic knowledge of geology.
Interns(s): Joshua Soble
Mentor(s):

Oliver Boyd, United States Geological Survey
Rob Williams, United States Geological Survey
Steve Hartzell, United States Geological Survey

InSAR Time Series with ALOS Data

Project Description: The intern will learn how to search for, download, and process InSAR data from a variety of satellites including ALOS, ERS 1 & 2, ENVISAT, etc. The intern will process data for a single area in Southern California and will explore the use of time series in order to evaluate deformation in the region. They will also compare their results to existing GPS observations within their target area.
Intern(s): Lauren Steinberg
Mentor(s):

Rowena Lohman, Cornell University

Assessing Status of Campaign GPS Observations

Project Description: The intern will set up a framework for assessing whether particular campaign GPS benchmarks should be reoccupied based on a variety of criteria. They will begin with a basic estimate on the strain rate at each site based on the crustal velocity model, and will determine how much deformation has built up since the last occupation of the site. This step will involve only basic skills of fitting a line to data. 2nd, they will use models of nearby faults, in conjunction with the location of nearby continuous GPS sites, to determine which campaign sites would add the most information about the Southern California network of faults.
Intern(s): Nathan Williams
Mentor(s):

Rowena Lohman, Cornell University

Using the SEATREE Framework to Understand Earthquake Catalog Uncertainty

Project Description: Seismic activity is recorded in earthquake catalogs, which are easily accessible and form the foundation of numerous scientific studies, such as attempts to identify deterministic patterns in earthquake occurrence. However, it is well known that even the best published catalogs are highly uneven in space and time, and strongly affected by imperfect seismometer distributions and uncertainties about the crust's velocity structure, to name a few. It is therefore crucial to obtain and convey a solid, quantitative understanding of regional catalog reliability and robustness to students and researchers alike. To this end, we propose to use the new Solid Earth Research and Teaching Environment (SEATREE, http://geosys.usc.edu/projects/seatree/) as a user-friendly computing platform to establish new seismology teaching modules. SEATREE implements an advanced, object-oriented and transparent way of using research tools at all user levels, from undergraduate to post-graduate level. With assistance from Becker and Bailey, the intern will assemble and implement currently used earthquake inversion tools (e.g. HASH, FPFIT, HypoDD) and Earth Science databases (e.g. SCEC network recordings and velocity model). This machinery will be incorporated into the existing SEATREE graphical user interface and infrastructure by means of writing Python computer language scripts. SEATREE is designed to facilitate such extensions and most of the work will be spent on the fun, science-near aspects. The goal is to assemble flexible computational modules that can be used to interactively perform event relocations, focal mechanism inversion, etc. using realistic datasets. By changing input parameters such as event/station distribution and Earth structure models, and evaluating graphically the predicted catalogs characteristics, new insights into local network performance and the reliability of catalog based inferences will be gained. The tools can be used for actual research as well as teaching purposes because the SEATREE design allows "looking under the hood" as well as "point and click", intuitive learning. The student will gain an appreciation for the nature and origin of crustal seismicity, inverse theory, and scientific data analysis. She/he will use learn advanced, object-oriented programming techniques and experience the fun of python programming. The final product will be shared openly on the web within the SEATREE framework and made available to all interested students, teachers, and researchers in the field.
Intern(s): Hannah Waterhouse
Mentor(s):

Thorsten Becker, University of Southern California
Iain Bailey, University of Southern California

Modeling the Dynamics of Complex Fault Branches

Project Description: A key aspect of seismic hazard evaluation is predicting the path of earthquake rupture on complex fault systems. This point has been emphasized by earthquakes such as the 1992 Landers, the 1999 Hector Mine, 2001 Kokoxili, Tibet, and the 2002 Denali Fault events, which all took place on “branched fault” systems. In all of these cases, a point of particular interest has been to explain why ruptures took one branch while abandoning another. We are searching for a SCEC Intern conduct computer modeling of the rupture dynamics of branched faults. Under the guidance of D. Oglesby (UCR) and D. Bowman (CSUF), the SCEC intern will construct, run, and analyze numerical models under a variety of assumptions about fault geometry and material properties. The suggested models will break new ground in dynamic modeling, but should be accessible to a motivated and technically competent undergraduate in the physical sciences. Over the period of this funded research, we plan to investigate the dynamics of fault systems such as:

• Multiple fault branches intersecting at a single line—which path is most likely, and how does rupture on one segment affect slip on neighboring segments?
• Fault branches that are separated by varying gaps—is the most likely branch the same if a gap is present for all branch segments?
• Fault branches where there is a damage zone in or near the branch region.

In all cases, we will compare our results with similar observed fault systems in nature.
Intern(s): Melissa Nunley
Mentor(s):

David Bowman, California State University, Fullerton

Age, Location and Renewal Rates of Precariously Balanced Rocks in Southern California

Project Description: We seek two enthusiastic interns to work together in the office and the field to 1) provide higher precision locations for previously mapped precariously balanced rocks, and 2) to help test a hypothesis about the erosion and “renewal” mechanisms for generating precariously balanced rocks. Reconnaissance surveys have located hundreds of precariously balanced rocks in Southern California in the last decade, and a number of studies are using them to place constraints on seismic hazard estimates (e.g., Brune et al. 2007, Purvance et al 2007). To make full use of the rocks we need to accurately locate them using Google Earth or similar tool, and determine the timescale and mechanisms for creating and exposing – i.e. renewing - these rocks. Since most of the rocks were originally corestones that have been exposed by erosion of decomposed granite (grus), it is important to understand the effect of erosion rate on the distribution of such rocks. A correlation that has been suggested by reconnaissance surveys in Nevada and Eastern California is that in many areas where there are zones with numerous precarious rocks next to zones where rocks have obviously been knocked down, and that the precarious rocks tend to appear on the steeper slopes where the erosion rate is presumably faster. This suggests that the rocks on older surfaces may have been knocked down by one or more early large earthquakes, and that the remaining precarious rocks have been exposed after the last earthquake by a more rapid erosion rate. Rapid erosion rate on the steep slope at the edge of a stream channel has exposed precarious rocks, whereas on the gentler slope away from the stream channel the rocks appear to have been shaken down. If true, then measurement of the erosion rate adjacent to the stream channel could be used to constrain time since the last strong earthquake. Since we now have methods of dating erosion rates through CRN, understanding this process can provide important information for about seismic hazard and random background earthquakes. The correlation of precariously balanced rocks with slope, and presumably erosion rate, has not been documented in Southern California. Most of the obvious examples to date have been found in Nevada and Eastern California, where the repeat times for large earthquakes are much greater than in Southern California. We posit that such a correlation exists in Southern California. We propose to supervise a pair of interns to investigate this possibility in Southern California.
Intern(s): Tyanna Schlom
Mentor(s):

Lisa Grant Ludwig, University of California, Irvine
James Brune, San Diego State University
Sinan Akciz, University of California, Los Angeles

Two Projects for Earthquake Education and Outreach: CSULA Earthquake Display; SCEC Plate Tectonics Learning Kits

Project Description: During the summer of 2008, I participated in SCEC’s internship program Summer Undergraduate Research Experience (SURE) where I worked on education and outreach projects. I was assigned two major projects that were designed to educate the general public on earthquake science and earthquake safety. The first project was the remodeling of the old earthquake display, located in California State University, Los Angeles’ Physical Sciences building. The old display consisted of visually unattractive signs, outdated computers, and a seismograph with the rotating drum. The new display now consists of more attractive signs, two computers (each with 28 inch LCD screens that display the latest earthquakes, globally and locally), and information on earthquake preparedness. The second project of the two was a mockup of SCEC’s “Plate Tectonics Learning Kit.” This kit builds on Purdue University’s professor Larry Braille’s earlier creation of the plate tectonics kit. The purpose of SCEC’s version of the kit is to educate students (primarily middle school students) about plate tectonics and its causes/effects. The kit includes USGS’ map This Dynamic Planet along with the plate boundaries on the back so that others may cut the individual plates out of the map. Once the map is cut into its pieces, it could then be used as a puzzle. The kit includes other smaller items that would facilitate the teaching of plate tectonics.
Intern(s): David Coss Y Leon
Mentor(s):

Mark Benthien, University of Southern California

Using Magnetic Inclination and Relative Paleointensity as a Means of Correlating and Dating Stratigraphy in the LA Basin

Project Description: Paleomagnetic data gathered from boreholes drilled across the locus of most recent folding above the Compton blind-thrust fault have proven useful in correlating stratigraphy between boreholes and in determining chronostratigraphy. We drilled 13 continuously cored boreholes, each with better than 95% recovery along a 1.4-km-long, north-south transect across the locus of back limb folding above the southern segment of the Compton thrust fault in Lakewood, CA. Our cores unearthed alternating intervals of course-grained sands, gravels, fine-grained silts, clays, and organic-rich clays down to a depth of ~40m. The main source of these sediments was most likely the San Gabriel river ~2 km East of the study site, with material possibly also coming from the Los Angeles river, ~7 km to the West. Correlations based on visual core descriptions provide one method of determining the timing and rate of uplift along the Compton blind-thrust, but in some structurally key locations, these correlations remain uncertain. Paleomagnetic inclination and relative paleointensity data are being tested as an alternative means of correlating and dating selected boreholes. Initially, we took ~70 samples every 125 cm along the entire downhole length of holes 10 and 11. Subsequently, we took ~230 samples spaced every 2.5 cm over an 8-m-thick clay interval near the base of holes 10, 11, and 12. Our initial results indicate that inclination and relative paleointensity can be correlated among holes. We may have also found evidence for the Mono Lake excursion at ~33ka, which would be consistent with 14C dates recovered from the cores. Recognition of this excursion and related paleomagnetic field variability, if confirmed by our ongoing work, will provide a useful means of stratigraphic correlation for late Pleistocene growth strata.
Intern(s): Trevor Thomas
Mentor(s):

James Dolan, University of Southern California

New Late Pleistocene and Holocene Slip Rates on the Southern Segment of the Compton Blind-Thrust Fault, Lakewood, California

Project Description: Newly collected borehole data from the southern segment of the Compton fault provide both Late Pleistocene and Holocene slip rates. Preliminary analysis of sediments extracted from our study site in the city of Lakewood, California (~35 km SE of downtown Los Angeles and 2 km West of the San Gabriel River), reveal an upward-narrowing zone of folding to within a few meters of the surface. Shaw and Suppe (1996) originally identified the Compton thrust through their observation on petroleum-industry seismic reflection data of a fault-bend fold associated with the thrust ramp. High-resolution seismic data were acquired in October 2007 to better image deformation associated with the Compton fault in young strata within the uppermost 200 m, above the shallowest industry data. During Summer 2008 we excavated seven boreholes to depths of 30- to 45 m along a 1.4-km-long, north-south transect across the backlimb active axial surface of the fault-bend fold above the ramp of the Compton Thrust. These boreholes, along with five boreholes excavated in 2007, reveal layers of fine- to coarse-grained sand and gravel interbedded with fine-grained silt and clay and organic-rich units. Radiocarbon dates from detrital charcoal and bulk-soil samples give ages ranging from ~2.3 ka to ~32 ka. Analysis of the borehole data yields slip rates for the Compton ramp averaged over two different time intervals: a 32 ka rate of 1.7 +0.2/-0.1 mm/yr, and a 10±2 ka rate of 1.9±0.5 mm/yr. These southern Compton segment slip rates are somewhat faster than the 1.2 +0.5/-0.3 mm/yr rate measured by Leon et al. (in review, 2008) along the northern segment. Ongoing analysis of the Lakewood borehole should provide a paleoseismologic record of individual earthquakes, as well as a greater understanding of the behavior of the segmented Compton blind-thrust fault.
Intern(s): Patrick Dooling, Angel Martinez
Mentor(s):

James Dolan, University of Southern California

Pioneering a Digital Archive for the Importation, Preservation, and Accessibility of Southern California Earthquake Center Records

Project Description: As computer-based technology is readily becoming more available and digital material is continuously being created, the need for a digital library emerges. The purpose of the Digital Library created for the Southern California Earthquake Center (SCEC) during the summer of 2008 is to communicate the Uniform California Earthquake Rupture Forecast (UCERF), Version 2 report, as well as to digitally preserve its contents and related materials. SCEC’s digital library is supported by the University of Southern California (USC) Libraries system, from which assets and metadata records are accessible to the public. An asset is a document or item that is to be digitally archived in one or many formats and is described by a metadata record. A metadata record is a brief overview that includes such information as a title, a short description, the author(s) name(s), keywords, etc. The process of creating a metadata record to archive an asset includes careful analysis of the asset’s content, the extraction of the asset’s key concepts, and the internal and external review necessary to preserve the integrity of the asset itself. The retrieval of pertinent information from an asset is required to prepare an accurate description of the document at hand. Also, a controlled vocabulary used to describe the assets is needed for consistency and precision. Internal review among the archiving individuals, as well as the collaboration with the authors of the assets and other persons familiar with the materials ensure an honest representation of the assets being digitally archived. The assets for which metadata records have been created for SCEC during the summer of 2008 include the UCERF main report, its appendices, tabular datasets, images, the SCEC-VDO software, the SCEC-VDO plug-ins, etc.
Intern(s): Christiann Boutwell
Mentor(s):

Thomas Jordan, University of Southern California

SCEC Education Program

Project Description:
Intern(s): Gema Venegas
Mentor(s):

Robert de Groot, University of Southern California