DOCSLIB.ORG

Site-Specific Seismic-Hazard Maps and Deaggregation in the Western United States Using the NGA Models for Ground-Motion Prediction

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Site-Specific Seismic-Hazard Maps and Deaggregation in the Western United States Using the NGA Models for Ground-Motion Prediction Site-Specific Seismic-Hazard Maps and Deaggregation in the Western United States Using the NGA Models for Ground-Motion Prediction By Stephen Harmsen Open-File Report 2011–1218 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2011 For product and ordering information: World Wide Web: http://www.usgs.gov/pubprod Telephone: 1–888–ASK–USGS For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment: World Wide Web: http://www.usgs.gov Telephone: 1–888–ASK–USGS Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. Suggested citation: Harmsen, Stephen, 2011, Site-specific seismic-hazard maps and deaggregation in the western United States using the NGA models for ground-motion prediction: U.S. Geological Survey Open-File Report 2011–1218, 67 p. ii Contents Abstract ...................................................................................................................................................................... 1 Introduction ................................................................................................................................................................. 1 Site Response in GMPEs ........................................................................................................................................... 3 Rock versus Soil in the Hazard Integral ...................................................................................................................... 4 Regional Scale Uniform Soil Hazard Maps ................................................................................................................. 6 Methods for Estimating Vs30 over Broad Regions ..................................................................................................... 9 Regional Scale Site-Specific Hazard Maps ................................................................................................................ 9 Regional Scale Site-Specific Vs30 Maps for Central California .............................................................................. 9 Regional Scale Site-Specific Hazard Maps for Central California ......................................................................... 15 Regional Scale Site-Specific Vs30 Maps for Southern California.......................................................................... 27 Regional Scale Site-Specific Hazard Maps for Southern California ...................................................................... 31 Deaggregation of Seismic Hazard at Specific Sites .................................................................................................. 44 Case I. Soil Mode Same as Rock Mode................................................................................................................ 45 Case 2. Soil Mode Different from Rock Mode ....................................................................................................... 49 Caveats and Model Limits ........................................................................................................................................ 59 Discussion and Conclusions ..................................................................................................................................... 63 Acknowledgments .................................................................................................................................................... 64 References ............................................................................................................................................................... 64 Figures Figure 1. Schematic diagram of spectral acceleration distribution from two types of sources recorded on two types of sites .................................................................................................................................................. 5 Figure 2. Spectral acceleration ratio for sites in the western United States, using the new Next Generation of Attenuation ground-motion prediction equations ........................................................................... 7 Figure 3. Regional scale site-specific Vs30 maps for central California using three methods to determine Vs30 .................................................................................................................................................. 10 Figure 4. Regional scale site-specific hazard maps for central California, 5-hertz spectral acceleration ............. 16 Figure 5. Regional scale site-specific hazard maps for central California, 3-second spectral acceleration .......... 22 Figure 6. Regional scale site-specific Vs30 maps for southern California using three methods to determine Vs30 .................................................................................................................................................. 28 Figure 7. Regional scale site-specific hazard maps for southern California, 5-hertz spectral acceleration .......... 32 Figure 8. Regional scale site-specific hazard maps for central California, 3-second spectral acceleration .......... 38 Figure 9. Map showing principal faults in the vicinity of the Los Angeles site over a base map showing the site-specific 1-second spectral acceleration at 2 percent in 50 years probability of exceedance, using method 1 to estimate Vs30 ....................................................................................................................... 46 Figure 10. Map showing principal faults in the vicinity of a site in San Jose, California, over a contour map showing site-specific 1-second spectral acceleration with 2 percent in 50 years probability of exceedance using method 1 to estimate Vs30 ................................................................................................... 48 Figure 11. Rock-site hazard near San Rafael: 5-hertz spectral acceleration with 2 percent in 50 years probability of exceedance for a site with Vs30 of 760 meters per second .......................................................... 51 Figure 12. Soil-site hazard near San Rafael: 5-hertz spectral acceleration with 2 percent in 50 years probability of exceedance for a site with Vs30 of 180 meters per second .......................................................... 52 Figure 13. Harbor Island 5-hertz hazard deaggregation assuming rock site condition ....................................... 54 iii Figure 14. Harbor Island 5-hertz hazard deaggregation assuming soil site condition ........................................ 55 Figure 15. Harbor Island 1-second spectral acceleration assuming rock site condition ..................................... 57 Figure 16. Harbor Island 1-second spectral acceleration assuming soil site condition ...................................... 58 Figure 17. Scattergram of Vs100 versus Vs30 at or near 50 southern California strong-motion sites ............... 62 Tables Table 1. Important future earthquake sources in Los Angeles, California. .......................................................... 45 Table 2. Seismic hazard at San Jose, California. ............................................................................................... 49 Table 3. Comparison of Vs30 values measured by one of three methods (borehole, spectral analysis of surface waves, or refraction microtremor) and Vs30 values from three regional model values. ......................... 60 List of Abbreviations Used in This Report μ and σ median and logarithmic standard deviation, respectively, of ground-motion prediction equation g gravitational acceleration at Earth surface, approximately equal to 9.8 m/s2 GMPE ground-motion prediction equation, also known as attenuation equation Hz hertz (frequency in cycles per second of seismic waves or building oscillations) IMW Intermountain West; a boundary that separates the central and western United States based on differences in attenuation of seismic waves in the Earth’s continental crust IP Intermediate-period; generally in the range 0.5 to 2.0 seconds km kilometer LP long-period; generally in the range 2.5 seconds or greater m meter NEHRP National Earthquake Hazard Reduction Program NGA Next Generation of Attenuation models (developed for tectonically active regions) NSHMP National Seismic Hazards Mapping Project (Golden, Colorado) PE probability of exceedence; probability that a specified ground acceleration or other intensity measure will be exceeded in a specified time, such as 50 years. Typically, PE values like 2% in 50 years or 10% in 50 years are considered. (Term coined for use in PSHA.) PGA peak (horizontal) ground acceleration; generally, PGA is the geometric mean of the two horizontal components PGV peak (horizontal) ground velocity PSHA probabilistic seismic hazard analysis SA 5% damped pseudo spectral acceleration SASW spectral analysis of surface waves SP short-period; generally in the range 0.01 to 0.4 seconds Vs30 average shear-wave velocity in upper 30 meters of the soil column iv Site-Specific Seismic-Hazard Maps and Deaggregation in the Western United States Using
Load more

Recommended publications
  • 2021 Oregon Seismic Hazard Database: Purpose and Methods
    State of Oregon Oregon Department of Geology and Mineral Industries Brad Avy, State Geologist DIGITAL DATA SERIES 2021 OREGON SEISMIC HAZARD DATABASE: PURPOSE AND METHODS By Ian P. Madin1, Jon J. Francyzk1, John M. Bauer2, and Carlie J.M. Azzopardi1 2021 1Oregon Department of Geology and Mineral Industries, 800 NE Oregon Street, Suite 965, Portland, OR 97232 2Principal, Bauer GIS Solutions, Portland, OR 97229 2021 Oregon Seismic Hazard Database: Purpose and Methods DISCLAIMER This product is for informational purposes and may not have been prepared for or be suitable for legal, engineering, or surveying purposes. Users of this information should review or consult the primary data and information sources to ascertain the usability of the information. This publication cannot substitute for site-specific investigations by qualified practitioners. Site-specific data may give results that differ from the results shown in the publication. WHAT’S IN THIS PUBLICATION? The Oregon Seismic Hazard Database, release 1 (OSHD-1.0), is the first comprehensive collection of seismic hazard data for Oregon. This publication consists of a geodatabase containing coseismic geohazard maps and quantitative ground shaking and ground deformation maps; a report describing the methods used to prepare the geodatabase, and map plates showing 1) the highest level of shaking (peak ground velocity) expected to occur with a 2% chance in the next 50 years, equivalent to the most severe shaking likely to occur once in 2,475 years; 2) median shaking levels expected from a suite of 30 magnitude 9 Cascadia subduction zone earthquake simulations; and 3) the probability of experiencing shaking of Modified Mercalli Intensity VII, which is the nominal threshold for structural damage to buildings.
    [Show full text]
  • Recommended Guidelines for Liquefaction Evaluations Using Ground Motions from Probabilistic Seismic Hazard Analyses
    RECOMMENDED GUIDELINES FOR LIQUEFACTION EVALUATIONS USING GROUND MOTIONS FROM PROBABILISTIC SEISMIC HAZARD ANALYSES Report to the Oregon Department of Transportation June, 2005 Prepared by Stephen Dickenson Associate Professor Geotechnical Engineering Group Department of Civil, Construction and Environmental Engineering Oregon State University ODOT Liquefaction Hazard Assessment using Ground Motions from PSHA Page 2 ABSTRACT The assessment of liquefaction hazards for bridge sites requires thorough geotechnical site characterization and credible estimates of the ground motions anticipated for the exposure interval of interest. The ODOT Bridge Design and Drafting Manual specifies that the ground motions used for evaluation of liquefaction hazards must be obtained from probabilistic seismic hazard analyses (PSHA). This ground motion data is routinely obtained from the U.S. Geologocal Survey Seismic Hazard Mapping program, through its interactive web site and associated publications. The use of ground motion parameters derived from a PSHA for evaluations of liquefaction susceptibility and ground failure potential requires that the ground motion values that are indicated for the site are correlated to a specific earthquake magnitude. The individual seismic sources that contribute to the cumulative seismic hazard must therefore be accounted for individually. The process of hazard de-aggregation has been applied in PSHA to highlight the relative contributions of the various regional seismic sources to the ground motion parameter of interest. The use of de-aggregation procedures in PSHA is beneficial for liquefaction investigations because the contribution of each magnitude-distance pair on the overall seismic hazard can be readily determined. The difficulty in applying de-aggregated seismic hazard results for liquefaction studies is that the practitioner is confronted with numerous magnitude-distance pairs, each of which may yield different liquefaction hazard results.
    [Show full text]
  • 1. Geology and Seismic Hazards
    8 PUBLIC SAFETY ELEMENT As required by State law, the Public Safety Element addresses the protection of the community from unreasonable risks from natural and manmade haz- ards. This Element provides information about risks in the Eden Area and delineates policies designed to prepare and protect the community as much as possible from the effects of: ♦ Geologic hazards, including earthquakes, ground-shaking, liquefaction and landslides. ♦ Flooding, including dam failures and inundation, tsunamis and seiches. ♦ Wildland fires. ♦ Hazardous materials. This Element also contains information and policies regarding general emer- gency preparedness. Each section includes background information on the particular hazard followed by goals, policies and actions designed to minimize risk for Eden Area residents. The Public Safety Element establishes mechanisms to prepare for and reduce death, injuries and damage to property from public safety hazards like flood- ing, fires and seismic events. Hazards are an unavoidable aspect of life, and the Public Safety Element cannot eliminate risk completely. Instead, the Element contains policies to create an acceptable level of risk. 1. GEOLOGY AND SEISMIC HAZARDS Earthquakes and secondary seismic hazards such as ground-shaking, liquefac- tion and landslides are the primary geologic hazards in the Eden Area. This section provides background on the seismic hazards that affect the Eden Area and includes goals, policies and actions to minimize these risks. 8-1 COUNTY OF ALAMEDA EDEN AREA GENERAL PLAN PUBLIC SAFETY ELEMENT A. Background Information As is the case in most of California, the Eden Area is subject to risks from seismic activity. The Eden Area is located in the San Andreas Fault Zone, one of the most seismically-active regions in the United States, which has generated numerous moderate to strong earthquakes in northern California and in the San Francisco Bay Area.
    [Show full text]
  • Bray 2011 Pseudostatic Slope Stability Procedure Paper
    Paper No. Theme Lecture 1 PSEUDOSTATIC SLOPE STABILITY PROCEDURE Jonathan D. BRAY 1 and Thaleia TRAVASAROU2 ABSTRACT Pseudostatic slope stability procedures can be employed in a straightforward manner, and thus, their use in engineering practice is appealing. The magnitude of the seismic coefficient that is applied to the potential sliding mass to represent the destabilizing effect of the earthquake shaking is a critical component of the procedure. It is often selected based on precedence, regulatory design guidance, and engineering judgment. However, the selection of the design value of the seismic coefficient employed in pseudostatic slope stability analysis should be based on the seismic hazard and the amount of seismic displacement that constitutes satisfactory performance for the project. The seismic coefficient should have a rational basis that depends on the seismic hazard and the allowable amount of calculated seismically induced permanent displacement. The recommended pseudostatic slope stability procedure requires that the engineer develops the project-specific allowable level of seismic displacement. The site- dependent seismic demand is characterized by the 5% damped elastic design spectral acceleration at the degraded period of the potential sliding mass as well as other key parameters. The level of uncertainty in the estimates of the seismic demand and displacement can be handled through the use of different percentile estimates of these values. Thus, the engineer can properly incorporate the amount of seismic displacement judged to be allowable and the seismic hazard at the site in the selection of the seismic coefficient. Keywords: Dam; Earthquake; Permanent Displacements; Reliability; Seismic Slope Stability INTRODUCTION Pseudostatic slope stability procedures are often used in engineering practice to evaluate the seismic performance of earth structures and natural slopes.
    [Show full text]
  • Long-Term Fault Slip Rates, Distributed Deformation Rates, and Forecast Of
    1 Long-term fault slip rates, distributed deformation rates, and forecast of seismicity 2 in the western United States from joint fitting of community geologic, geodetic, 3 and stress-direction datasets 4 Peter Bird 5 Department of Earth and Space Sciences 6 University of California 7 Los Angeles, CA 90095-1567 8 [email protected] 9 Second revision of 2009.07.08 for J. Geophys. Res. (Solid Earth) 10 ABSTRACT. The long-term-average velocity field of the western United States is computed 11 with a kinematic finite-element code. Community datasets include fault traces, geologic offset 12 rates, geodetic velocities, principal stress directions, and Euler poles. There is an irreducible 13 minimum amount of distributed permanent deformation, which accommodates 1/3 of Pacific- 14 North America relative motion in California. Much of this may be due to slip on faults not 15 included in the model. All datasets are fit at a common RMS level of 1.8 datum standard 16 deviations. Experiments with alternate weights, fault sets, and Euler poles define a suite of 17 acceptable community models. In pseudo-prospective tests, fault offset rates are compared to 18 126 additional published rates not used in the computation: 44% are consistent; another 48% 19 have discrepancies under 1 mm/a, and 8% have larger discrepancies. Updated models are then 20 computed. Novel predictions include: dextral slip at 2~3 mm/a in the Brothers fault zone, two 21 alternative solutions for the Mendocino triple junction, slower slip on some trains of the San 22 Andreas fault than in recent hazard models, and clockwise rotation of some domains in the 23 Eastern California shear zone.
    [Show full text]
  • Report of Geotechnical Investigation Proposed Improvements
    REPORT OF GEOTECHNICAL INVESTIGATION PROPOSED IMPROVEMENTS PROPOSED RIO HONDO SATELLITE CAMPUS EL RANCHO ADULT SCHOOL 9515 HANEY STREET PICO RIVERA, CALIFORNIA Prepared for: RIO HONDO PROGRAM MANAGEMENT TEAM Whittier, California January 20, 2016 Project 4953-15-0302 January 20, 2016 Mr Luis Rojas Rio Hondo Program Management Team c/o Rio Hondo College 3600 Workman Mill Road Whittier, California 90601-1699 Subject: LETTER OF TRANSMITTAL Report of Geotechnical Investigation Proposed Improvements Proposed Rio Hondo Satellite Campus El Rancho Adult School 9515 Haney Street Pico Rivera, California, 90660 Amec Foster Wheeler Project 4953-15-0302 Dear Mr. Rojas: We are pleased to submit the results of our geotechnical investigation for the proposed improvements as part of the proposed Rio Hondo Satellite Campus at the El Rancho Adult School in Pico Rivera, California. This investigation was performed in general accordance with our proposal dated November 24, 2015, which was authorized by e-mail on December 15, 2015. The scope of our services was planned with Mr. Manuel Jaramillo of DelTerra. We have been furnished with a site plan and a general description of the proposed improvements. The results of our investigation and design recommendations are presented in this report. Please note that you or your representative should submit copies of this report to the appropriate governmental agencies for their review and approval prior to obtaining a permit. Correspondence: Amec Foster Wheeler 6001 Rickenbacker Road Los Angeles, California 90040 USA
    [Show full text]
  • Seismic Hazards Mapping Act Fact Sheet
    Department of Conservation California Geological Survey Seismic Hazards Mapping Act Fact Sheet The Seismic Hazards Mapping Act (SHMA) of 1990 (Public Resources Code, Chapter 7.8, Section 2690-2699.6) directs the Department of Conservation, California Geological Survey to identify and map areas prone to earthquake hazards of liquefaction, earthquake-induced landslides and amplified ground shaking. The purpose of the SHMA is to reduce the threat to public safety and to minimize the loss of life and property by identifying and mitigating these seismic hazards. The SHMA was passed by the legislature following the 1989 Loma Prieta earthquake. Staff geologists in the Seismic Hazard Mapping Program (Program) gather existing geological, geophysical and geotechnical data from numerous sources to compile the Seismic Hazard Zone Maps. They integrate and interpret these data regionally in order to evaluate the severity of the seismic hazards and designate Zones of Required Investigation for areas prone to liquefaction and earthquake–induced landslides. Cities and counties are then required to use the Seismic Hazard Zone Maps in their land use planning and building permit processes. The SHMA requires site-specific geotechnical investigations be conducted identifying the seismic hazard and formulating mitigation measures prior to permitting most developments designed for human occupancy within the Zones of Required Investigation. The Seismic Hazard Zone Maps identify where a site investigation is required and the site investigation determines whether structural design or modification of the project site is necessary to ensure safer development. A copy of each approved geotechnical report including the mitigation measures is required to be submitted to the Program within 30 days of approval of the report.
    [Show full text]
  • An Elusive Blind-Thrust Fault Beneath Metropolitan Los Angeles
    R EPORTS 5 The intercept of the line with the abscissa yields Di/D 1/4, which is an extreme case, differs only by 36. N. A. Sulpice and R. J. D’Arcy, J. Phys. E 3, 477 (1970). 7% as compared with D 5 0. DV. This geometry-independent constant is i 37. Electrical charging due to the electron beam cannot 31. Microscopy was performed with a Philips CM30 200- account for the effect, because the charge found to characteristic for the specific nanotube under kV high-resolution TEM. reside on the nanotubes is positive rather than neg- investigation and is typically on the order of 32. The ripple mode may be a precursor to buckling, but ative. Furthermore, the amplitude of vibration at several volts. Similarly, attaching nanoscopic it should not be confused with bucking. Buckling (in resonance does not change with electron dose, as it contrast to rippling) is characterized as an instability would if electron beam charging were important. conducting particles to the nanotubes facilitates giving rise to a nonlinear response. It occurs in highly 38. M. Gurgoze, J. Sound Vib. 190, 149 (1996). measurements of their work functions. stressed nanotubes (and beams) and manifests as 39. We thank U. Landman, R. L. Whetten, L. Forro, and A. The methods developed here are also well one or several kinks with very small radii of curvature Zangwill for fruitful discussion and R. Nitsche for his suited to measure masses in the picogram-to- (about 1 to 10 nm). It is accompanied by abrupt analysis of the static bent nanotube.
    [Show full text]
  • STRUCTURAL GEOLOGY and TECTONICS DIVISION Newsletter Volume 13, Number 1 March 1994
    STRUCTURAL GEOLOGY and TECTONICS DIVISION Newsletter Volume 13, Number 1 March 1994 CHAIRPERSON'S MESSAGE Division activities at the annual meeting in Boston were quite successful. John Bartley became the new second vice chair, Ed Beutner moved up to first vice-chair and Art Goldstein is the new secretary-treasurer. We all thank the past secretary-treasurer, Don Secor, for keeping the Division running properly during his record tenure of six years. The papers at Division sessions were excellent, so interesting to me that I spent the meeting in these sessions and missed the exhibits. Thanks to Fred Chester and Ron Bruhn for organizing a really cutting-edge symposium on inferring paleoearthquakes from fault-rock fabrics. It appears that this seemingly intractable problem has some solutions. We can expect some significant publications from the speakers. Terry Engelder, with help from Mike Gross and Mark Fischer presented the Division's short course on fracture mechanics of rock. The course was highly praised by everyone I heard from; thanks guys. As always, it was a pleasure to attend the Division's award ceremony to honor the recipients and to hear the citations and responses. As Darrel Cowan, in his citation of Ben Page for the Career Contribution Award, summarized Ben's significant publications, I was intrigued as I realized that my list would have been as long but different. Such a broad range of important contributions is an excellent qualification for this award. Mark Cloos cited Dan Worrall and Sig Snelson for the best paper award for their 1989 DNAG paper "Evolution of the northern Gulf of Mexico, with emphasis on Cenozoic growth faulting and the role of salt." This paper contains important new insights into regional salt tectonics as well as helps highlight a large region of very active tectonics that misses out on being a classic orogenic belt only because it is not forming mountains.
    [Show full text]
  • 3-8 Geologic-Seismic
    Environmental Evaluation 3-8 GEOLOGIC-SEISMIC Changes Since the Draft EIS/EIR Subsequent to the release of the Draft EIS/EIR in April 2004, the Gold Line Phase II project has undergone several updates: Name Change: To avoid confusion expressed about the terminology used in the Draft EIS/EIR (e.g., Phase I; Phase II, Segments 1 and 2), the proposed project is referred to in the Final EIS/EIR as the Gold Line Foothill Extension. Selection of a Locally Preferred Alternative and Updated Project Definition: Following the release of the Draft EIS/EIR, the public comment period, and input from the cities along the alignment, the Construction Authority Board approved a Locally Preferred Alternative (LPA) in August 2004. This LPA included the Triple Track Alternative (2 LRT and 1 freight track) that was defined and evaluated in the Draft EIS/EIR, a station in each city, and the location of the Maintenance and Operations Facility. Segment 1 was changed to extend eastward to Azusa. A Project Definition Report (PDR) was prepared to define refined station and parking lot locations, grade crossings and two rail grade separations, and traction power substation locations. The Final EIS/EIR and engineering work that support the Final EIS/EIR are based on the project as identified in the Final PDR (March 2005), with the following modifications. Following the PDR, the Construction Authority Board approved a Revised LPA in June 2005. Between March and August 2005, station options in Arcadia and Claremont were added. Changes in the Discussions: To make the Final EIS/EIR more reader-friendly, the following format and text changes have been made: Discussion of a Transportation Systems Management (TSM) Alternative has been deleted since the LPA decision in August 2004 eliminated it as a potential preferred alternative.
    [Show full text]
  • Iv.E Geology
    IV.E GEOLOGY 1.0 INTRODUCTION This section of the Draft Environmental Impact Report (EIR) identifies and evaluates geologic and soils conditions at Loyola Marymount University (LMU) campus that could affect, or be affected by, implementation of the Proposed Project. The information contained in this section is based on a geotechnical evaluation1 prepared by MACTEC Engineering and Consulting, Inc., (MACTEC) prepared in July 2009, which is provided in Appendix IV.E. 2.0 REGULATORY FRAMEWORK 2.1 State and Regional Regulations 2.1.1 Seismic Hazards Mapping Act Under the Seismic Hazards Mapping Act of 1990, the State Geologist is responsible for identifying and mapping seismic hazards zones as part of the California Geological Survey. The Geological Survey provides zoning maps of non-surface rupture earthquake hazards (including liquefaction and seismically induced landslides) to local governments for planning purposes. These maps are intended to protect the public from the risks involved with strong ground shaking, liquefaction, landslides or other ground failure, and other hazards caused by earthquakes. For projects within seismic hazard zones, the Seismic Hazards Mapping Act requires developers to conduct geological investigations and incorporate appropriate mitigation measures into project designs before building permits are issued. Most of the Southern California region has been mapped. Established by the Seismic Safety Commission Act in 1975, the State Seismic Safety Commission’s purpose is to provide oversight, review, and recommendations to the Governor and State Legislature regarding seismic issues. 2.1.2 Alquist-Priolo Earthquake Fault Zoning Act The Alquist-Priolo Earthquake Fault Zoning Act (the Act) (Public Resource Code Section 2621.5) of 1972 was enacted in response to the 1971 San Fernando earthquake, which caused extensive surface fault ruptures that damaged numerous homes, commercial buildings, and other structures.
    [Show full text]
  • Quaternary Fault and Fold Database of the United States
    Jump to Navigation Quaternary Fault and Fold Database of the United States As of January 12, 2017, the USGS maintains a limited number of metadata fields that characterize the Quaternary faults and folds of the United States. For the most up-to-date information, please refer to the interactive fault map. Lower Elysian Park thrust (Class A) No. 134 Last Review Date: 2017-06-14 citation for this record: Bryant, W.A., compiler, 2017, Fault number 134, Lower Elysian Park thrust, in Quaternary fault and fold database of the United States: U.S. Geological Survey website, https://earthquakes.usgs.gov/hazards/qfaults, accessed 12/14/2020 02:13 PM. Synopsis Davis and others (1989) interpret the Elysian Park anticlinorium to be formed by stacked fault propagation folds; Elysian Park thrust is the lower ramp. The thrust propagates upward from an assumed detachment at about 15 km to a depth of about 10 km. Shaw and Suppe (1996) prefer a fault-bend fold model that links the Elysian Park fault ramp with the Compton [133] ramp to the west. This is implied by the similar kink band widths (growth triangles) associated with the two ramps. They define two segments of the Elysian Park Thrust (Los Angeles and Whittier) that are offset in the vicinity of the Whittier Narrows earthquake. Schneider and others (1996) define the Los Angeles fault as that responsible for ongoing deformation of the south facing monocline that forms the northern Los Angeles shelf, based on structural reconstruction from well log data and seismic stratigraphy. In well logs they recognize increasing dip with depth, suggesting that fold growth has been by progressive limb rotation.
    [Show full text]