Appendix N—Grand Inversion Implementation and Testing
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Introduction San Andreas Fault: an Overview
Introduction This volume is a general geology field guide to the San Andreas Fault in the San Francisco Bay Area. The first section provides a brief overview of the San Andreas Fault in context to regional California geology, the Bay Area, and earthquake history with emphasis of the section of the fault that ruptured in the Great San Francisco Earthquake of 1906. This first section also contains information useful for discussion and making field observations associated with fault- related landforms, landslides and mass-wasting features, and the plant ecology in the study region. The second section contains field trips and recommended hikes on public lands in the Santa Cruz Mountains, along the San Mateo Coast, and at Point Reyes National Seashore. These trips provide access to the San Andreas Fault and associated faults, and to significant rock exposures and landforms in the vicinity. Note that more stops are provided in each of the sections than might be possible to visit in a day. The extra material is intended to provide optional choices to visit in a region with a wealth of natural resources, and to support discussions and provide information about additional field exploration in the Santa Cruz Mountains region. An early version of the guidebook was used in conjunction with the Pacific SEPM 2004 Fall Field Trip. Selected references provide a more technical and exhaustive overview of the fault system and geology in this field area; for instance, see USGS Professional Paper 1550-E (Wells, 2004). San Andreas Fault: An Overview The catastrophe caused by the 1906 earthquake in the San Francisco region started the study of earthquakes and California geology in earnest. -
3.6 Geology and Soils
3. Environmental Setting, Impacts, and Mitigation Measures 3.6 Geology and Soils 3.6 Geology and Soils This section describes and evaluates potential impacts related to geology and soils conditions and hazards, including paleontological resources. The section contains: (1) a description of the existing regional and local conditions of the Project Site and the surrounding areas as it pertains to geology and soils as well as a description of the Adjusted Baseline Environmental Setting; (2) a summary of the federal, State, and local regulations related to geology and soils; and (3) an analysis of the potential impacts related to geology and soils associated with the implementation of the Proposed Project, as well as identification of potentially feasible mitigation measures that could mitigate the significant impacts. Comments received in response to the NOP for the EIR regarding geology and soils can be found in Appendix B. Any applicable issues and concerns regarding potential impacts related to geology and soils that were raised in comments on the NOP are analyzed in this section. The analysis included in this section was developed based on Project-specific construction and operational features; the Paleontological Resources Assessment Report prepared by ESA and dated July 2019 (Appendix I); and the site-specific existing conditions, including geotechnical hazards, identified in the Preliminary Geotechnical Report prepared by AECOM and dated September 14, 2018 (Appendix H).1 3.6.1 Environmental Setting Regional Setting The Project Site is located in the northern Peninsular Ranges geomorphic province close to the boundary with the Transverse Ranges geomorphic province. The Transverse Ranges geomorphic province is characterized by east-west trending mountain ranges that include the Santa Monica Mountains. -
5.4 Geology and Soils
BEACH BOULEVARD SPECIFIC PLAN DRAFT EIR CITY OF ANAHEIM 5. Environmental Analysis 5.4 GEOLOGY AND SOILS This section of the Draft Environmental Impact Report (DEIR) evaluates the potential for implementation of the Beach Boulevard Specific Plan (Proposed Project) to impact geological and soil resources in the City of Anaheim. 5.4.1 Environmental Setting Regulatory Setting California Alquist-Priolo Earthquake Fault Zoning Act The Alquist-Priolo Earthquake Fault Zoning Act was signed into state law in 1972. Its primary purpose is to mitigate the hazard of fault rupture by prohibiting the location of structures for human occupancy across the trace of an active fault. The act delineates “Earthquake Fault Zones” along faults that are “sufficiently active” and “well defined.” The act also requires that cities and counties withhold development permits for sites within an earthquake fault zone until geologic investigations demonstrate that the sites are not threatened by surface displacement from future faulting. Pursuant to this act, structures for human occupancy are not allowed within 50 feet of the trace of an active fault. Seismic Hazard Mapping Act The Seismic Hazard Mapping Act (SHMA) was adopted by the state in 1990 to protect the public from the effects of nonsurface fault rupture earthquake hazards, including strong ground shaking, liquefaction, seismically induced landslides, or other ground failure caused by earthquakes. The goal of the act is to minimize loss of life and property by identifying and mitigating seismic hazards. The California Geological Survey (CGS) prepares and provides local governments with seismic hazard zone maps that identify areas susceptible to amplified shaking, liquefaction, earthquake-induced landslides, and other ground failures. -
And Short-Term Stress Interaction of the 2019 Ridgecrest Sequence and Coulomb-Based Earthquake Forecasts Shinji Toda*1 and Ross S
Special Section: 2019 Ridgecrest, California, Earthquake Sequence Long- and Short-Term Stress Interaction of the 2019 Ridgecrest Sequence and Coulomb-Based Earthquake Forecasts Shinji Toda*1 and Ross S. Stein2 ABSTRACT We first explore a series of retrospective earthquake interactions in southern California. M ≥ ∼ We find that the four w 7 shocks in the past 150 yr brought the Ridgecrest fault 1 bar M M closer to failure. Examining the 34 hr time span between the w 6.4 and w 7.1 events, M M we calculate that the w 6.4 event brought the hypocentral region of the w 7.1 earth- M quake 0.7 bars closer to failure, with the w 7.1 event relieving most of the surrounding M stress that was imparted by the first. We also find that the w 6.4 cross-fault aftershocks M shut down when they fell under the stress shadow of the w 7.1. Together, the Ridgecrest mainshocks brought a 120 km long portion of the Garlock fault from 0.2 to 10 bars closer to failure. These results motivate our introduction of forecasts of future seismicity. Most attempts to forecast aftershocks use statistical decay models or Coulomb stress transfer. Statistical approaches require simplifying assumptions about the spatial distribution of aftershocks and their decay; Coulomb models make simplifying assumptions about the geometry of the surrounding faults, which we seek here to remove. We perform a rate– state implementation of the Coulomb stress change on focal mechanisms to capture fault complexity. After tuning the model through a learning period to improve its forecast abil- ity, we make retrospective forecasts to assess model’s predictive ability. -
More Fault Connectivity Is Needed in Seismic Hazard Analysis
More Fault Connectivity Is Needed in Seismic Hazard Analysis Morgan T. Page*1 ABSTRACT Did the third Uniform California Earthquake Rupture Forecast (UCERF3) go overboard with multifault ruptures? Schwartz (2018) argues that there are too many long ruptures in the model. Here, I address his concern and show that the UCERF3 rupture-length distribution matches empirical data. I also present evidence that, if anything, the UCERF3 model could be improved by adding more connectivity to the fault system. Adding more connectivity would improve model misfits with data, particularly with paleoseismic data on the southern San Andreas fault; make the model less characteristic on the faults; potentially improve aftershock forecasts; and reduce model sensitivity to inadequacies and unknowns in the modeled fault system. Furthermore, I argue that not only was the inclusion of mul- KEY POINTS tifault ruptures an improvement on past practice, as it allows • The UCERF3 model has a rupture-length distribution that the model to include ruptures much like those that have been matches empirical data. observed in the past, but also that there is still further progress • Adding more connectivity to UCERF3 would improve data that can be made in this direction. Further increasing connec- misfits. tivity in hazard models such as UCERF will reduce model mis- • More connectivity in seismic hazard models would make fits, as well as make the model less sensitive to inadequacies in them less sensitive to fault model uncertainties. the fault model and provide a better approximation of the Supplemental Material natural system. RUPTURE-LENGTH DISTRIBUTION In a recent article, Schwartz (2018) criticizes the UCERF3 INTRODUCTION model and suggests that it has too many long ruptures (i.e., The third Uniform California Earthquake Rupture Forecast those with rupture lengths ≥100 km). -
Region of the San Andreas Fault, Western Transverse Ranges, California
Thrust-Induced Collapse of Mountains— An Example from the “Big Bend” Region of the San Andreas Fault, Western Transverse Ranges, California By Karl S. Kellogg Scientific Investigations Report 2004–5206 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior Gale A. Norton, Secretary U.S. Geological Survey Charles G. Groat, Director U.S. Geological Survey, Reston, Virginia: 2004 For sale by U.S. Geological Survey, Information Services Box 25286, Denver Federal Center Denver, CO 80225 For more information about the USGS and its products: Telephone: 1-888-ASK-USGS World Wide Web: http://www.usgs.gov/ Any use of trade, product, or firm names in this publication 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. iii Contents Abstract ……………………………………………………………………………………… 1 Introduction …………………………………………………………………………………… 1 Geology of the Mount Pinos and Frazier Mountain Region …………………………………… 3 Fracturing of Crystalline Rocks in the Hanging Wall of Thrusts ……………………………… 5 Worldwide Examples of Gravitational Collapse ……………………………………………… 6 A Spreading Model for Mount Pinos and Frazier Mountain ………………………………… 6 Conclusions …………………………………………………………………………………… 8 Acknowledgments …………………………………………………………………………… 8 References …………………………………………………………………………………… 8 Illustrations 1. Regional geologic map of the western Transverse Ranges of southern California …………………………………………………………………………… 2 2. Simplified geologic map of the Mount Pinos-Frazier Mountain region …………… 2 3. View looking southeast across the San Andreas rift valley toward Frazier Mountain …………………………………………………………………… 3 4. View to the northwest of Mount Pinos, the rift valley (Cuddy Valley) of the San Andreas fault, and the trace of the Lockwood Valley fault ……………… 3 5. -
Simulation Based Earthquake Forecasting with Rsqsim
Simulation Based Earthquake Forecasting with RSQSim Jacqui Gilchrist Tom Jordan (USC/SCEC), Jim Dieterich (UCR), Keith Richards-Dinger (UCR), Bruce Shaw (Columbia), and Kevin Milner (USC/SCEC) SSA Annual Meeting April 18th, 2017 – Denver, CO Main Objectives Develop a physics-based forecasting model for earthquake rupture in California Produce a suite of catalogs (~50) to investigate the epistemic uncertainty in the physical parameters used in the simulations. One million years of simulated time Several million M4-M8 events Varied simulation parameters and fault models Compare with other models (UCERF3) to see what we can learn from the differences. RSQSim: Rate-State earthQuake Simulator (Dieterich & Richards-Dinger, 2010; Richards-Dinger & Dieterich, 2012) • Multi-cycle earthquake simulations (full cycle model) • Interseismic period -> nucleation and rupture propagation • Long catalogs • Tens of thousands to millions of years with millions of events • Complicated model geometry • 3D fault geometry; rectangular or triangular boundary elements • Different types of fault slip • Earthquakes, slow slip events, continuous creep, and afterslip • Physics based • Rate- and State-dependent friction • Foreshocks, aftershocks, and earthquake sequences • Efficient algorithm • Event driven time steps • Quasi-dynamic rupture propagation California Earthquake Forecasting Models Reid renewal Omori-Utsu clustering Simulator-based UCERF UCERF3 long-term UCERF3 short-term UCERF2 STEP/ETAS NSHM long-term short-term renewal models “medium-term gap” clustering models Century Decade Year Month Week Day Anticipation Time Use of simulations for long-term assessment of earthquake probabilities Inputs to simulations Use tuned earthquake simulations to generate earthquake rate models RSQSim Calibration Develop a model that generates an earthquake catalog that matches observed California seismicity as closely as possible. -
Potential for a Large Earthquake Near Los Angeles Inferred from the 2014
PUBLICATIONS Earth and Space Science RESEARCH ARTICLE Potential for a large earthquake near Los Angeles 10.1002/2015EA000113 inferred from the 2014 La Habra earthquake Key Points: Andrea Donnellan1,2, Lisa Grant Ludwig3, Jay W. Parker1, John B. Rundle4, Jun Wang5, Marlon Pierce5, • UAVSAR and GPS results of the M5.1 6 1 La Habra earthquake show broad Geoffrey Blewitt , and Scott Hensley deformation 1 2 • Concurrent slip on several shallow Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA, Department of Earth Sciences, 3 structures best explains the University of Southern California, Loa Angeles, California, USA, Program in Public Health, University of California, Irvine, observations California, USA, 4Departments of Physics and Geology, University of California, Davis, California, USA, 5University • We show a time-independent Information Technology Services, Indiana University, Bloomington, Indiana, USA, 6Nevada Geodetic Laboratory, Nevada means of estimating the potential for future events Bureau of Mines and Geology, University of Nevada, Reno, Nevada Abstract Tectonic motion across the Los Angeles region is distributed across an intricate network of strike-slip Correspondence to: and thrust faults that will be released in destructive earthquakes similar to or larger than the 1933 M6.4 Long A. Donnellan, Beach and 1994 M6.7 Northridge events. Here we show that Los Angeles regional thrust, strike-slip, and [email protected] oblique faults are connected and move concurrently with measurable surface deformation, even in moderate magnitude earthquakes, as part of a fault system that accommodates north-south shortening and westerly Citation: tectonic escape of northern Los Angeles. The 28 March 2014 M5.1 La Habra earthquake occurred on a Donnellan,A.,L.GrantLudwig,J.W.Parker, J. -
Nehrp Final Technical Report
NEHRP FINAL TECHNICAL REPORT Grant Number: G16AP00097 Term of Award: 9/2016-9/2017, extended to 12/2017 PI: Whitney Maria Behr1 Quaternary geologic slip rates along the Agua Blanca fault: implications for hazard to southern California and northern Baja California Abstract The Agua Blanca and San Miguel-Vallecitos Faults transfer ~14% of San Andreas-related Pacific-North American dextral plate motion across the Peninsular Ranges of Baja California. The Late Quaternary slip histories for the these faults are integral to mapping how strain is transferred by the southern San Andreas fault system from the Gulf of California to the western edge of the plate boundary, but have remained inadequately constrained. We present the first quantitative geologic slip rates for the Agua Blanca Fault, which of the two fault is characterized by the most prominent tectonic geomorphologic evidence of significant Late Quaternary dextral slip. Four slip rates from three sites measured using new airborne lidar and both cosmogenic 10Be exposure and optically stimulated luminescence geochronology suggest a steady along-strike rate of ~3 mm/a over 4 time frames. Specifically, the most probable Late Quaternary slip rates for the Agua Blanca Fault are 2.8 +0.8/-0.6 mm/a since ~65.1 ka, 3.0 +1.4/-0.8 mm/a since ~21.8 ka, 3.4 +0.8/-0.6 mm/a since ~11.8 ka, and 3.0 +3.0/-1.5 mm/a since ~1.6 ka, with all uncertainties reported at 95% confidence. These rates suggest that the Agua Blanca Fault accommodates at least half of plate boundary slip across northern Baja California. -
A Pattern of Seismicity in Southern California: the Possibility of Earthquakes Triggered by Lunar and Solar Gravitational Tides
A Pattern of Seismicity in Southern California: The Possibility of Earthquakes Triggered by Lunar and Solar Gravitational Tides David Nabhan Helen Keller wrote that the heresy of one age is the orthodoxy of the next, giving ample proof that although sightless, she possessed extraordinary vision. Moreover, it has been said that every new fact must pass through a crucible by which first it is ignored or ridiculed, then vigorously attacked, and finally accepted as though the truth had been apparent from the beginning. Earthquake prediction is no exception but for the anomaly that the first two stages have endured far longer than what the immense populations on the U.S. West Coast might hope to expect regarding a matter so important to their safety and welfare. Residents of Southern California have been left with a bewildering set of claims and counter-claims regarding this issue for many decades. While scientific data Seismic Gap Probabilities. Author's collection. can be presented any number of ways to say any number of things, there is another arbiter that, weighed alongside the conflicting findings, may allow fair-minded observers to come to their own cogent conclusions: history. There exists a long and verifiable record of events on the Pacific Coast and elsewhere David Nabhan, SDSU alumnus, is the author of Earthquake Prediction: Answers in Plain Sight (2012) and two other books on the subject. He is directing a public opinion campaign to impel the governor of California to convene the California Earthquake Prediction Evaluation Council for the purposes of determining the viability or fallibility of a seismic safety plan. -
Geologic, Climatic, and Vegetation History of California
GEOLOGIC, CLIMATIC, AND VEGETATION HISTORY OF CALIFORNIA Constance I. Millar I ntroduction The dawning of the “Anthropocene,” the era of human-induced climate change, exposes what paleoscientists have documented for decades: earth’s environment—land, sea, air, and the organisms that inhabit these—is in a state of continual flux. Change is part of global reality, as is the relatively new and disruptive role humans superimpose on environmental and climatic flux. Historic dynamism is central to understanding how plant lineages exist in the present—their journey through time illuminates plant ecology and diversity, niche preferences, range distributions, and life-history characteristics, and is essential grounding for successful conservation planning. The editors of the current Manual recognize that the geologic, climatic, and vegetation history of California belong together as a single story, reflecting their interweaving nature. Advances in the sci- ences of geology, climatology, and paleobotany have shaken earlier interpretations of earth’s history and promoted integrated understanding of the origins of land, climate, and biota of western North America. In unraveling mysteries about the “what, where, and when” of California history, the respec- tive sciences have also clarified the “how” of processes responsible for geologic, climatic, and vegeta- tion change. This narrative of California’s prehistory emphasizes process and scale while also portraying pic- tures of the past. The goal is to foster a deeper understanding of landscape dynamics of California that will help toward preparing for changes coming in the future. This in turn will inform meaningful and effective conservation decisions to protect the remarkable diversity of rock, sky, and life that is our California heritage. -
216166963.Pdf
SEISMOLOGICAL RESEARCH ISSUES IN THE SAN DIEGO REGION Thomas H. Heaton and Lucile M. Jones U.S. Geological Survey 525 S. Wilson Ave. Pasadena, CA 911 04 June 1989 INTRODUCTION What is the nature of earthquake ground motions that can be expected in San Diego's foreseeable future? Although this is the most basic of questions underlying the adequate design of structures to resist earthquakes, answers to this question are disturbingly uncertain. A reasonable assumption is that future earthquake ground motions will be similar to those that have occurred in the past. When compared with San Francisco or Los Angeles, San Diego has historically experienced relatively mild earthquake shaking. Unfortunately, San Diego's written history is very short compared to the time scales of earthquake repetition. Are there sources of earthquakes that may cause damage in San Diego and what is their frequency? Mapping of geologic structures and the study of patterns of small earthquakes are the primary tools for recognizing potentially active faults. There are features in both the geologic structure and the seismicity that are suggestive of major active faults that could pose a serious hazard to San Diego. Furthermore, there is evidence that the rate of occurrence of small earthquakes has increased within the last 5 years when compared with the previous 50 years. However, these features are not well studied or understood. Even if the potential sources of earthquakes were well understood, the problem of anticipating the range of future ground motions is difficult. The nature of shaking from earthquakes is strongly affected by the nature of seismic wave propagation through complex geologic structures (path effects).