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USGS1966

Jura tectonics as a décollement

For many years the structure of the Jura Mountains was interpreted as a décollement whose origin was related to the Alps; in recent years, however, this mode of origin has been questioned. Most of the alternative explanations recognize a décollement to some extent, but attribute it to movement of the basement beneath. Surface and subsurface data are here reviewed to show that the Jura deformation was produced in a gliding sheet, in which the forces of gravity and inertia were generated within the total moving mass. Features of the folded Jura which support the décollement hypothesis are: (1) Nowhere are rocks older than Middle Triassic exposed, which strongly suggests that the folding does not extend to the older rocks. (2) Subsurface data in the Lons-le-Saunier region clearly show that the external border of the Jura has moved northwestward over the eastern margin of the Bresse Basin. (3) Lower Jurassic rocks rest on Upper Jurassic along a horizontal fault 1234 m deep in the Risoux well near the middle of the Jura. (4) The tabular areas, with their absence of folds, are expectable in a décollement. (5) High-angle tear faults, interpreted as not extending into the basement, are normal features of a décollement sheet. A continuous décollement around the southwestern end of the Swiss Plain can reasonably be inferred, connecting the internal Jura, the Salève, and the Subalpine folds as part of the décollement mass. Elsewhere, the internal border of décollement extends southeastward into the Molasse basin for an unknown distance and probably underlies the entire basin; if it does, a causal relation to the Alps is indicated. © 1966, The Geological Society of America, Inc.

Geological Society of America Bulletin↗

USGS2024

Plan to coordinate post-earthquake investigations supported by the National Earthquake Hazards Reduction Program (NEHRP)

Introduction This report presents a plan supported by the National Earthquake Hazards Reduction Program (NEHRP) to coordinate domestic and international post-earthquake investigations (herein called “the Plan”). Post-earthquake scientific and engineering investigations are undertaken to capture critical information to understand the causes and impacts of the event, lessons from which can substantially improve the Nation’s resilience after future earthquakes. NEHRP is the Federal Government’s coordinated nationwide program to reduce risks to life and property from earthquakes. The Plan describes the activation and coordination of the four designated NEHRP Agencies in the Federal Government: Federal Emergency Management Agency, National Institute of Standards and Technology, U.S. National Science Foundation, and U.S. Geological Survey (USGS). The Plan also describes coordination between NEHRP Agencies and other organizations that may participate in pre-event and post-earthquake investigations, including non-NEHRP Federal agencies; State, regional, local, Tribal, and territorial agencies; domestic nongovernmental organizations; academic institutions and affiliated organizations; private companies; foreign governmental agencies and nongovernmental organizations; and international organizations. The Plan delineates the coordination of NEHRP post-earthquake scientific and engineering investigations to document the direct, indirect, and cascading physical and societal impacts from fault rupture and ground shaking hazards and from secondary hazards such as landslides, liquefaction, and tsunamis. In addition, the Plan identifies pre-event activities necessary to ensure that post-earthquake investigations are executed effectively. The USGS is the lead NEHRP Agency for activating and coordinating NEHRP post-earthquake investigations and for implementing this Plan. The USGS also leads coordination of the NEHRP Agencies in completing the pre-event activities identified in the Plan. The Plan has new information and supersedes USGS Circular 1242, “The Plan to Coordinate NEHRP Post-Earthquake Investigations,” which was published in 2003. This second-generation Plan was developed with the assistance of the Applied Technology Council (ATC) of Redwood City, California, under USGS contract 140G0121P0309, ATC-155. A 17-member Project Review Panel provided guidance on plan development, and input was solicited from subject matter experts representing key stakeholder groups and from participants at a public workshop.

Circular↗

USGS1969

Critical review of some multivariate procedures in the analysis of geochemical data

Simulation experiments have been conducted to examine the potential usefulness of R-mode and Q-mode factor methods in the analysis and interpretation of geochemical data. The R-mode factor analysis experiment consisted of constructing a factor model, using the model to generate a correlation matrix, and attempting to recover the model by R-mode techniques. The techniques were successful in determining the number of factors in the model, but the factor loadings could not be estimated even approximately on the basis of mathematical procedures alone. Q-mode factor methods were successful in recovering all of the properties of a model used to generate hypothetical chemical data on olivine samples , but it was necessary to use a correction previously regarded as unimportant.

Journal of the International Association for Mathe↗

USGS1983

Characteristic analysis-1981: Final program and a possible discovery

The latest ornewest version of thecharacteristicanalysis (NCHARAN)computer program offers the exploration geologist a wide variety of options for integrating regionalized multivariate data. The options include the selection of regional cells for characterizing deposit models, the selection of variables that constitute the models, and the choice of logical combinations of variables that best represent these models. Moreover, the program provides for the display of results which, in turn, makes possible review, reselection, and refinement of a model. Most important, the performance of the above-mentioned steps in an interactive computing mode can result in a timely and meaningful interpretation of the data available to the exploration geologist. The most recent application of characteristic analysis has resulted in the possible discovery of economic sulfide mineralization in the Grong area in central Norway. Exploration data for 27 geophysical, geological, and geochemical variables were used to construct a mineralized and a lithogeochemical model for an area that contained a known massive sulfide deposit. The models were applied to exploration data collected from the Gjersvik area in the Grong mining district and resulted in the identification of two localities of possible mineralization. Detailed field examination revealed the presence of a sulfide vein system and a partially inverted stratigraphic sequence indicating the possible presence of a massive sulfide deposit at depth. ?? 1983 Plenum Publishing Corporation.

Journal of the International Association for Mathe↗

USGS2016

A software tool for rapid flood inundation mapping

The GIS Flood Tool (GFT) was developed by the U.S. Geological Survey with support from the U.S. Agency for International Development’s Office of U.S. Foreign Disaster Assistance to provide a means for production of reconnaissance-level flood inundation mapping for data-sparse and resource-limited areas of the world. The GFT has also attracted interest as a tool for rapid assessment flood inundation mapping for the Flood Inundation Mapping Program of the U.S. Geological Survey. The GFT can fill an important gap for communities that lack flood inundation mapping by providing a first-estimate of inundation zones, pending availability of resources to complete an engineering study. The tool can also help identify priority areas for application of scarce flood inundation mapping resources. The technical basis of the GFT is an application of the Manning equation for steady flow in an open channel, operating on specially processed digital elevation data. The GFT is implemented as a software extension in ArcGIS. Output maps from the GFT were validated at 11 sites with inundation maps produced previously by the Flood Inundation Mapping Program using standard one-dimensional hydraulic modeling techniques. In 80 percent of the cases, the GFT inundation patterns matched 75 percent or more of the one-dimensional hydraulic model inundation patterns. Lower rates of pattern agreement were seen at sites with low relief and subtle surface water divides. Although the GFT is simple to use, it should be applied with the oversight or review of a qualified hydraulic engineer who understands the simplifying assumptions of the approach.

Open-File Report↗

USGS2021

Leveraging existing technology: Developing a trusted digital repository for the U.S. Geological Survey

As Federal Government agencies in the United States pivot to increase access to scientific data (Sheehan, 2016), the U.S. Geological Survey (USGS) has made substantial progress (Kriesberg et al., 2017). USGS authors are required to make federally funded data publicly available in an approved data repository (USGS, 2016b). This type of public data product, known as a USGS data release, serves as a method for publishing reviewed and approved data. In this paper, we present major milestones in the approach the USGS took to transition an existing technology platform to a Trusted Digital Repository. We describe both the technical and the non-technical actions that contributed to a successful outcome.We highlight how initial workflows revealed patterns that were later automated, and the ways in which assessments and user feedback influenced design and implementation. The paper concludes with lessons learned, such as the importance of a community of practice, application programming interface (API)-driven technologies, iterative development, and user-centered design. This paper is intended to offer a potential roadmap for organizations pursuing similar goals.

International Journal of Digital Curation↗

USGS2008

Geographic Names of Iceland's Glaciers: Historic and Modern

Climatic changes and resulting glacier fluctuations alter landscapes. In the past, such changes were noted by local residents who often documented them in historic annals; eventually, glacier variations were recorded on maps and scientific reports. In Iceland, 10 glacier place-names are to be found in Icelandic sagas, and one of Iceland's ice caps, Snaefellsjokull, appeared on maps of Iceland published in the 16th century. In the late 17th century, the first description of eight of Iceland's glaciers was written. Therefore, Iceland distinguishes itself in having a more than 300-year history of observations by Icelanders on its glaciers. A long-term collaboration between Oddur Sigurdsson and Richard S. Williams, Jr., led to the authorship of three books on the glaciers of Iceland. Much effort has been devoted to documenting historical glacier research and related nomenclature and to physical descriptions of Icelandic glaciers by Icelanders and other scientists from as far back as the Saga Age to recent (2008) times. The first book, Icelandic Ice Mountains, was published by the Icelandic Literary Society in 2004 in cooperation with the Icelandic Glaciological Society and the International Glaciological Society. Icelandic Ice Mountains was a glacier treatise written by Sveinn Palsson in 1795 and is the first English translation of this important scientific document. Icelandic Ice Mountains includes a Preface, including a summary of the history and facsimiles of page(s) from the original manuscript, a handwritten copy, and an 1815 manuscript (without maps and drawings) by Sveinn Palsson on the same subject which he wrote for Rev. Ebenezer Henderson; an Editor's Introduction; 82 figures, including facsimiles of Sveinn Palsson's original maps and perspective drawings, maps, and photographs to illustrate the text; a comprehensive Index of Geographic Place-Names and Other Names in the treatise; References, and 415 Endnotes. Professional Paper 1746 (this book) is the second of the three books; it is being published in both English and Icelandic editions. This book provides information about all named glaciers in Iceland, historic and modern. Descriptions, with geographic coordinates, and bibliographic citations to all glacier place-names on published maps, books, and scientific articles are included. Maps, oblique aerial photographs, ground photographs, and satellite images document each of the 269 modern named glaciers of Iceland. The third book, Glaciers of Iceland, is Chapter D of the 11-chapter [volume] U.S. Geological Survey Professional Paper 1386-A-K. Chapter D includes a 1:500,000-scale Map of the Glaciers of Iceland; it is a comprehensive historical and modern review and assessment of what is currently known about glaciers in Iceland's eight Regional Glacier Groups from a review of the scientific literature and from analysis of maps and remotely sensed data (ground, airborne, and satellite); topics include geology and geography, climate and climate variability, types of glaciers, history of glacier variation (including the 21 surge-type glaciers), and frequency and magnitude of volcanic and lacustrine jokulhlaups.

Professional Paper↗

USGS1995

Beach-steps: An evolutionary perspective

Field observation of contrasting beach-step behavior at Canaveral National Seashore on two subsequent days when incident-wave conditions in the inner surf zone were similar prompted this re-examination of our conceptual and quantitative understanding of beach steps. These lower-foreshore features are more complex than previously assumed, evolving through erosional as well as accretional phases, and displaying equifinality in geometric form but not necessarily internal sedimentary structure. Past and recent evidence is reviewed that links beach steps to incident waves at the surging-plunging transition and to the action of a backwash vortex. Tides and low-frequency waves likely play no direct role in beach-step initiation, although their presence can have pronounced influences on modulating nearshore hydrodynamics, and thus, on beach-step maintenance and evolution. A generalized, conceptual model capturing these aspects of beach-step dynamics is presented. Beach-step initiation proceeds via step “carving”, “excavation”, or “building” depending on the erosional-accretional character of the beach-foreshore system. Subsequent evolution of the step form may take one of several alternative morphodynamic pathways including stepface “retreat”, step “drag down”, or step “infilling/elimination” depending on tidal stage/range or wave set-up/setdown. Additional data on equilibrium beach-step forms and associated morphodynamic and hydrodynamic conditions in the field are necessary before quantitative models of beach-step existence and evolution can be formulated with realistic results.

Marine Geology↗

USGS2022

#TheSmoreYouKnow and #emergencycute: A conceptual model on the use of humor by science agencies during crisis to create connection, empathy, and compassion

Studies from a variety of disciplines reveal that humor can be a useful method to reduce stress and increase compassion, connection, and empathy between agencies and people they serve during times of crisis. Despite this growing evidence base, humor's use during a geohazard (earthquake, volcanoes , landslides, and tsunami) to aid scientific agencies' crisis communication response has been rarely studied. A broad literature review of humor in crisis and an exploratory examination of several case studies reveal that scientific organizations, specifically those that respond to geohazards, can harness the power of humor to help create connection and empathy with the publics they seek to serve. We find evidence that supports our argument that the use of humor acknowledges a shared human experience, reducing the barriers between public officials, scientists, and the people most impacted by crisis. Public statements made by scientists and public officials during the U.S. Geological Survey (USGS) response to the Kīlauea eruption in 2018 in Hawai'i, United States, and GNS Science/GeoNet (GeoNet) response to the M7.8 Kaikōura/North Hurunui earthquake in 2016 in Aotearoa New Zealand, are used to inform the development of this conceptual model. We then posit a conceptual model which unifies concepts from the literature with our case studies to provide potential guidelines for those crisis communicators working for science agencies on how best to use humor to help people cope during times of crisis. This model can be further tested for future research to determine its effectiveness and utility for scientific agencies responding to geological crises.

International Journal of Disaster Risk Reduction↗

USGS2000

A paleolatitude approach to assessing surface temperature history for use in burial heating models

Calculations using heat flow theory as well as case histories show that over geologic time scales (10 6 years), changes in mean annual surface temperature (T s ) on the order of 10°C penetrate kilometers deep into the crust. Thus, burial heating models of sedimentary basins, which typically span kilometers in depth and persist over geological time frames, should consider T s history to increase their accuracy. In any case, T s history becomes important when it changes enough to be detected by a thermal maturation index like vitrinite reflectance, a parameter widely used to constrain burial heating models. Assessment of the general temperature conditions leading to petroleum generation indicates that changes in T s as small as 6°C can be detected by vitrinite reflectance measurements. This low temperature threshold indicates that oil and gas windows can be significantly influenced by T s history. A review of paleoclimatic factors suggests the significant and geologically resolvable factors affecting T s history are paleolatitude, long-term changes between cool and warm geological periods (climate mode), the degree to which a basin is removed from the sea (geographic isolation), and elevation or depth relative to sea level. Case studies using geologically realistic data ranges or different methods of estimating T s in a burial heating model indicate a significant impact of Ts when: (1) continental drift, subduction, tectonism and erosion significantly change paleolatitude, paleoaltitude, or paleogeography; (2) strata are at, or near, maximum burial, and changes in T s directly influence maximum burial temperature; and (3), when a significant change in T s occurs near the opening or closing of the oil or gas windows causing petroleum generation to begin or cease. Case studies show that during the burial heating and petroleum generation phase of basin development changes in climate mode alone can influence T s by about 15°C. At present, T s changes from the poles to the equator by about 50°C. Thus, in extreme cases, continental drift alone can seemingly produce T s changes on the order of 50°C over a time frame of 107 years.

International Journal of Coal Geology↗

USGS2006

Hydratools manual version 1.0, documentation for a MATLAB ® -based post-processing package for the Sontek Hydra

The Sediment Transport Instrumentation Group (STG) at the U.S. Geological Survey (USGS) Woods Hole Science Center has a long-standing comitment to providing scientists with high quality oceanographic data. To meet this commitment, STG personnel are vigilant in checking data as well as hardware for signs of instrument malfunction. STG data sets are accompanied by processing histories to detail data processing procedures that may have modified the natural data signal while removing noise from the data. The history also allows the data to be reprocessed in the ligth of new insight into instrument function and moored conditions. This toolbox was compiled to meet these data quality commitments for data generated by Sontek Hydra systems using both ADV and PCADP probes. In the mid 1900's, the USGS Coastal and Marine Program began frequent deployments of Sontek Hydra systems in support of projects in estuaries, coastal, and continental shelf regions nationwide. Hydra data sets are large and complex in structure, and existing processing and editing tools consisted of fragments of MATLAB code written by USGS scientists to satisfy personal research needs. This code did not meet STG quality control criteria. This toolbox permits engineers and scientists to monitor data quality by: 1. processing data with interactive critical review; 2. preserving data quality indicators; 3. preserving minimally processed and partially processed versions of data sets. STG usually deploys ADV and PCADP probes configured as downward looking, mounted on bottom tripods, with the objective of measuring high-resolution near-bed currents. The velocity profiles are recorded with minimal internal data processing. Also recorded are parameters such as temperature, conductivity, optical backscatter, light transmission, and high frequency pressure. Sampling consists of high-frequency bursts(1–10 Hz) bursts of long duration (5–30 minutes) at regular and recurring intervals for a duration of 1 to 6 months. The result is very large data files, often 500 MB per Hydra, per deployment, in Sontek's compressed binary format. This section introduces the Hydratools toolbox and provides information about the history of the system's development. The USGS philosophy regarding data quality is discussed to provide an understating of the motivation for creating the system. General information about the following topics will also be discussed: hardware and software required for the system, basic processing steps, limitations of program usage, and features that are unique to the programs.

Open-File Report↗

USGS2005

Coral disease and health workshop: Coral histopathology II, July 12-14, 2005

The health and continued existence of coral reef ecosystems are threatened by an increasing array of environmental and anthropogenic impacts. Coral disease is one of the prominent causes of increased mortality among reefs globally, particularly in the Caribbean. Although over 40 different coral diseases and syndromes have been reported worldwide, only a few etiological agents have been confirmed; most pathogens remain unknown and the dynamics of disease transmission, pathogenicity and mortality are not understood. Causal relationships have been documented for only a few of the coral diseases, while new syndromes continue to emerge. Extensive field observations by coral biologists have provided substantial documentation of a plethora of new pathologies, but our understanding, however, has been limited to descriptions of gross lesions with names reflecting these observations (e.g., black band, white band, dark spot). To determine etiology, we must equip coral diseases scientists with basic biomedical knowledge and specialized training in areas such as histology, cell biology and pathology. Only through combining descriptive science with mechanistic science and employing the synthesis epizootiology provides will we be able to gain insight into causation and become equipped to handle the pending crisis. One of the critical challenges faced by coral disease researchers is to establish a framework to systematically study coral pathologies drawing from the field of diagnostic medicine and pathology and using generally accepted nomenclature. This process began in April 2004, with a workshop titled Coral Disease and Health Workshop: Developing Diagnostic Criteria co-convened by the Coral Disease and Health Consortium (CDHC), a working group organized under the auspices of the U.S. Coral Reef Task Force, and the International Registry for Coral Pathology (IRCP). The workshop was hosted by the U.S. Geological Survey, National Wildlife Health Center (NWHC) in Madison, Wisconsin and was focused on gross morphology and disease signs observed in the field. A resounding recommendation from the histopathologists participating in the workshop was the urgent need to develop diagnostic criteria that are suitable to move from gross observations to morphological diagnoses based on evaluation of microscopic anatomy. As a continuation of building the foundation and framework for coral disease diagnostics, the CDHC convened the Coral Disease and Health Workshop: Coral Histopathology II in Charleston, South Carolina, July 11-14, 2005. The workshop was hosted by the Department of Pathology and Laboratory Medicine at the Medical University of South Carolina, Charleston, SC which provided expertise, facilities and equipment in support of the workshop. All of the histological slides and related photographs used in the discussions were prepared and supplied by the IRCP. This workshop brought together 15 experts in veterinary and medical pathology and coral biology from national and international research institutes and government laboratories. The mission was to devise a standardized approach to examining microscopic anatomy and pathology of corals and a standardized nomenclature to facilitate accurate descriptions of the microscopic morphology of corals and enhance communication among specialists investigating causes of coral death. 2 The participants of this workshop deliberated for 3 days to refine the nomenclature for gross and microscopic anatomy of corals and systematically described microscopic changes associated with selected coral diseases. The findings and recommendations from the deliberations will be submitted to the research community for peer review. The standardized nomenclature and descriptions produced at this workshop will ultimately be made available to the scientific community through a variety of media including the World Wide Web. An exciting highlight of this meeting was provided by Professor Robert Ogilvie (MUSC Department of Cell Biology and Anatomy) when he introduced participants to a new digital technology that is revolutionizing histology and histopathology in the medical field. The Virtual Slide technology creates digital images of histological tissue sections by computer scanning actual slides in high definition and storing the images for retrieval and viewing. Virtual slides now allow any investigator with access to a computer and the web to view, search, annotate and comment on the same tissue sections in real time. Medical and veterinary slide libraries across the country are being converted into virtual slides to enhance biomedical education, research and diagnosis. The coral health and disease researchers at this workshop deem virtual slides as a significant way to increase capabilities in coral histology and a means for pathology consultations on coral disease cases on a global scale.

NOAA Technical Memorandum↗

USGS2018

Development of a domestic earthquake alert protocol combining the USGS pager and FEMA Hazus systems

The U.S. Geological Survey’s PAGER automated alert system provides rapid (10-20 min) loss estimates in terms of ranges of fatalities and economic impact for all significant earthquakes around the globe. In contrast, FEMA’s Hazus software, which is currently operated manually by FEMA personnel internally within several hours of any large domestic earthquake, provides more detailed loss information quantified in terms of physical damage to the building stock, as well as a broad range of social and economic consequences estimated at a much higher spatial resolution (census-tract level). Hazus was originally designed for FEMA’s mitigation planning, but has been used of late for post-earthquake situational awareness. While the quick alerts generated automatically by the PAGER system are a suitable way to initially identify consequences for earthquakes, there remains a need to provide detailed loss information for facilitating a wider array of post-earthquake decisions among emergency managers. As such, we have developed a prototype summary product that takes advantage of the benefits of both these loss models for significant domestic earthquakes. The signature product, a new twoPAGER report, will serve as a supplement to the widely deployed standard onePAGER product for all significant domestic earthquakes. Page one is the standard, automated PAGER alert content, with summary alert levels for overall fatality and economic loss estimates, as well as summary content on recent earthquakes, structure vulnerability, and historical secondary hazards. As soon as the Hazus run using the most up-to-date version of the USGS ShakeMap is completed and reviewed by both agencies, the second alert page will be generated and delivered via the USGS website as an update. This second page will contain a summary of the more comprehensive Hazus model results, including spatially distributed estimates of: affected population, economic impact, non-fatal injuries, displaced households, and damage to structures (including potential building safety evaluation requirements). This enhancement does not affect the timeliness and the importance of the initial (onePAGER) alerting content for significant earthquakes; however, the twoPAGER report will provide more detailed, damage and loss/impact content for the Nation in the critical hours following a damaging earthquake.

Conference Paper↗

USGS2024

Developing and implementing an International Macroseismic Scale (IMS) for earthquake engineering, earthquake science, and rapid damage assessment

Executive Summary Macroseismic observations and analysis connect our collective seismological past with the present and the present to the future by facilitating hazard estimates and communicating the effects of ground shaking to a wide variety of audiences across the ages. Invaluable ground shaking and building damage information is gained through standardized, systematic approaches for assigning intensities and, importantly, sharing and archiving those assignments in a reproducible form. The applications for these assignments are far reaching. Traditional macroseismic surveys provide vital constraints on critical aspects of earthquakes and their effects on society, whereas internet-based macroseismic datasets are extremely valuable for real-time earthquake situational awareness, and they contribute to later engineering loss and risk analyses. These important applications of macroseismic observations would be helped by revisiting traditional macroseismic surveys for modern environments, standardizing internet-based collection strategies, and ensuring compatibility between traditional and internet-based approaches of macroseismic data collection. Even with best practices, we have identified several limitations with modern macroseismic data collection approaches, particularly from the U.S. Geological Survey's perspective. First, whereas crowdsourced, internet-based intensities such as “Did You Feel It?” are robust and definitive for lower intensities, they are poorly defined above intensity VII, where damage observations may require expert knowledge of each building’s structural system. Second, in the United States, we use the Modified Mercalli Intensity (MMI) Scale, which is consistent with—yet inferior to—the more recently developed European Macroseismic Scale (EMS–98; Grünthal and others, 1998). Similarly, New Zealand uses the New Zealand MMI Scale (Dowrick and others, 2008), which lacks detail on how to assign intensities above MMI VIII. The EMS–98 fundamentally advanced the science of macroseismic intensity assignment by requiring quantitative assessments at each location through consistent application on statistical ranges of well-defined damage grades to building-specific vulnerability classes. Lastly, the United States and New Zealand no longer have professionals dedicated to conducting traditional macroseismic field surveys, so a strategy is needed for allowing postearthquake building inspectors and insurance loss assessors to contribute to intensity assignments. The goals of our International Macroseismic Scale workshop were thus twofold. First, harmonize the MMI Scale with EMS–98 for the United States and New Zealand—which share several similar building types—by considering those structures and associated damage grades that are not well represented in the current EMS–98 building vulnerability class table. Second, begin to formalize the process of augmenting EMS–98 with new regional building classes and damage grades toward the development of a macroseismic scale that can be used globally, beyond the United States and New Zealand. Such an effort necessarily requires reviewing and expanding the original EMS–98 explanatory documents and consideration of any required revisions. We can build on the shoulders of giants in that a few of the original EMS–98 developers and experts participated in and were integral to our workshop. Their background and guidance were key in moving forward toward an international scale. We agreed that additional building vulnerability classes, damage grades, and written and pictorial descriptions are necessary and ideally accompanied by a detailed paper trail for other nations to follow. If we can improve the macroseismic assignment process in both nations, we can also aim to refine the process of collecting postearthquake impact data, a boon to many engineering and financial concerns. The benefits of a truly International Macroseismic Scale are considerable for both the engineering and seismology communities. A modern macroseismic scale requires more deliberate archival damage data collection, motivating more consistent and accessible postevent datasets that would have applications beyond the specific event. Applying field-collected building damage data toward macroseismic assignments would allow for increased coordination between engineering reconnaissance teams and local inspectors in collecting such data for official purposes. In addition, rapid and consistent intensity assignments globally would enable more accurate ShakeMaps—and thus improved earthquake engineering and geotechnical forensics, loss and risk estimates, and correlations between macroseismic intensity and ground motion parameters. A brief summary of the Powell Center IMS workshop was published by Wald and others (2023) in the magazine Eos. This Open-File Report describes the workshop, its discussions, and its outcomes in detail. In summarizing the workshop, we have added important background material and reflections for proper context.

Open-File Report↗

USGS1990

Paleontological analysis of a lacustrine carbonaceous uranium deposit at the Anderson mine, Date Creek basin, west-central Arizona (U.S.A.)

The Tertiary sedimentary sequence of the Date Creek basin area of Arizona is composed principally of intertonguing alluvial-fan and lacustrine deposits. The lacustrine rocks contain large intermediate- to, locally, high-grade uranium deposits that form one of the largest uranium resources in the United States (an estimated 670,000 tons of U 3 O 8 at an average grade of 0.023% is indicated by drilling to date). At the Anderson mine, about 50,000 tons of U 3 O 8 occurs in lacustrine carbonaceous siltstones and mudstones (using a cutoff grade of 0.01%). The Anderson mine constitutes a new class of ore deposit, a lacustrine carbonaceous uranium deposit. Floral and faunal remains at the Anderson mine played a critical role in creating and documenting conditions necessary for uranium mineralization. Organic-rich, uraniferous rocks at the Anderson mine contain plant remains and ostracodes having remarkably detailed preservation of internal features because of infilling by opaline silica. This preservation suggests that the alkaline lake waters in the mine area contained high concentrations of dissolved silica and that silicification occurred rapidly, before compaction or cementation of the enclosing sediment. Uranium coprecipitated with the silica. Thinly laminated, dark-colored, siliceous beds contain centric diatoms preserved with carbonaceous material suggesting that lake waters at the mine were locally deep and anoxic. These alkaline, silica-charged waters and a stagnant, anoxic environment in parts of the lake were necessary conditions for the precipitation of large amounts of uranium in the lake-bottom sediments. Sediments at the Anderson mine contain plant remains and pollen that were derived from diverse vegetative zones suggesting about 1500 m of relief in the area at the time of deposition. The pollen suggests that the valley floor was semiarid and subtropical, whereas nearby mountains supported temperate deciduous forests.

Nevada↗

USGS1983

Petroleum and mineral resources of Antarctica

No known petroleum or mineral resources occur in Antarctica. The data on these subjects have been collected, mainly since the IGY (International Geophysical Year), 1957-58, as a part of other research carried out by geologists and geophysicists from a number of countries. Specific resource-related studies have not been made. Wright and Williams (1974) summarized what was known of Antarctic mineral resources a decade ago. The U.S. Geological Survey has been actively pursuing various investigations in Antarctica since 194 7. In the course of this work and that of our colleagues elsewhere in the United States and in other countries, much information relevant to petroleum and mineral resources has been obtained. Since 1976, modern state-of-the-art multichannel seismic reflection and aeromagnetic surveys by several countries over the continental margin of Antarctica have indicated thick sedimentary basins. However, no offshore drilling beneath the continental shelf has taken place since the DSDP (Deep Sea Drilling Project) holes in the Ross Sea in 1973. Geologic field investigations begun at the turn of the twentieth century have been intensified in the past two decades; most rock outcrops have been visited and samples collected. Technology to exploit resources, particularly in the Arctic, has been developing at a rapid rate, and much of it could be applied to Antarctica. As a result of the petroleum price increases of the past decade, the attention of a number of countries has turned to Antarctica, but under the policy of "voluntary restraint" adopted by the Antarctic Treaty nations, no active petroleum or mineral exploration is taking place. The Antarctic treaty countries are in the process of negotiating an Antarctic mineral resources regime that is anticipated to be completed within the next several years. Therefore it seemed timely to us to readdress the question of petroleum and mineral resources. These reports review and summarize the available information. The first report summarizes the information relevant to petroleum resources. Although uneconomic at present, petroleum is generally considered more likely to be exploited (if supergiant fields were ever found) in the next few decades than hard minerals. The second report reviews the reported occurrences of minerals in Antarctica and discusses their significance. The final report discusses the Dufek layered mafic intrusion, second only to the Bushveld Complex in size in the world; the Dufek intrusion might be considered as a potential target for mineral exploration.

Circular↗

USGS2012

Deep-Sea Turbidites as Guides to Holocene Earthquake History at the Cascadia Subduction Zone—Alternative Views for a Seismic-Hazard Workshop

This report reviews the geological basis for some recent estimates of earthquake hazards in the Cascadia region between southern British Columbia and northern California. The largest earthquakes to which the region is prone are in the range of magnitude 8-9. The source of these great earthquakes is the fault down which the oceanic Juan de Fuca Plate is being subducted or thrust beneath the North American Plate. Geologic evidence for their occurrence includes sedimentary deposits that have been observed in cores from deep-sea channels and fans. Earthquakes can initiate subaqueous slumps or slides that generate turbidity currents and which produce the sedimentary deposits known as turbidites. The hazard estimates reviewed in this report are derived mainly from deep-sea turbidites that have been interpreted as proxy records of great Cascadia earthquakes. The estimates were first published in 2008. Most of the evidence for them is contained in a monograph now in press. We have reviewed a small part of this evidence, chiefly from Cascadia Channel and its tributaries, all of which head offshore the Pacific coast of Washington State. According to the recent estimates, the Cascadia plate boundary ruptured along its full length in 19 or 20 earthquakes of magnitude 9 in the past 10,000 years; its northern third broke during these giant earthquakes only, and southern segments produced at least 20 additional, lesser earthquakes of Holocene age. The turbidite case for full-length ruptures depends on stratigraphic evidence for simultaneous shaking at the heads of multiple submarine canyons. The simultaneity has been inferred primarily from turbidite counts above a stratigraphic datum, sandy beds likened to strong-motion records, and radiocarbon ages adjusted for turbidity-current erosion. In alternatives proposed here, this turbidite evidence for simultaneous shaking is less sensitive to earthquake size and frequency than previously thought. Turbidites far below a channel confluence, instead of representing the merged flows from two tributaries, monitor the dominant tributary only. Sandy beds low in the turbidites, instead of matching from channel to channel, permit divergent stratigraphic correlations; and rather than approximating strong-motion seismograms, the sandy beds more likely record processes internal to the generation and transformation of subaqueous mass movements. The age adjustments, instead of supporting other evidence that all the northern ruptures were long, are uncertain enough to accord with variation in rupture mode, and this variation improves agreement with onshore paleoseismology. Many of the turbidites counted as evidence for frequent earthquakes on the southern Cascadia plate boundary may instead reflect nearness to steep slopes. This report is meant to aid in the updating of national maps of seismic hazards in Canada and the United States. It offers three main conclusions for consideration at a U.S. hazard-map workshop slated for March 21-22, 2012: If giant earthquakes are the norm for the plate boundary offshore southern Washington, the strongest paleoseismic evidence for this rupture mode is the average earthquake-recurrence interval of about 500 years that is evidenced both offshore in lower Cascadia Channel and onshore at estuaries of southern Washington and northernmost Oregon. The plate boundary offshore southern British Columbia and northern Washington may be capable of producing great earthquakes at an average interval as short as 300 years that is evidenced mainly onshore. Review of more of the turbidite evidence now in press may clarify implications for the hazard maps. Further work on the deep-sea turbidites could target sedimentary processes and chronological uncertainties that may affect the turbidites' sensitivity to fault-rupture lengths and recurrence rates.

Washington;Oregon;California↗

USGS2002

Geologic map transecting the highland/lowland boundary zone, Arabia Terra, Mars; quadrangles 30332, 35332, 40332, and 45332

Arabia Terra is a large region of cratered terrane extending from about 20° W. longitude eastward across the prime meridian to about 300° W. longitude for an average east-west width of about 5,000 km. The northern boundary ranges from 40° N. to 45° N.; the southern boundary is a poorly defined zone at about 0° N. Thus, the north-south width is about 2,500 km. Except for the westernmost part, Arabia Terra has an albedo higher than surrounding terranes. The four quadrangles mapped (30332, 35332, 40332, 45332) provide a north-south strip from highland terrane in the south to lowland terrane in the north. The northern portion of Arabia Terra is the type region for both fretted terrane and fretted valleys and, along with the immediately adjacent northern plains, is also the site of some of the best examples of putative flow deposits present as aprons around isolated knobs and mesas or as deposits on the floors of fretted valleys and on the lowland surface. Mass wasting, eolian erosion or deposition, glacial scouring, fluvial or shoreline erosion, deposition from an ocean, hydrovolcanism, plateau volcanism, and faulting have all been proposed to account for the topography and crater characteristics in northern Arabia Terra. Although underlain by what appears to be typical highland terrane, Arabia Terra is anomalously low, with elevations generally below the planetary reference. Probably the most important question concerning the global-scale tectonic history of Mars is the origin of the crustal dichotomy. The northern lowland is not only several kilometers lower than the southern highland, it also is surfaced by materials that are significantly younger than surface materials in the southern highland. The young surface materials in the lowland rest unconformably on basement material having an age comparable to the exposed ancient highland terrane to the south. The age of the dichotomy continues to be controversial, as does the mechanism for its formation, as reviewed by McGill and Squyres (1991). Gravity and topography data from Mars Global Surveyor, however, does appear to favor early formation due to internal processes. Because complex depositional and erosional events affected the boundary since its formation, the cause and history of these events must be unraveled before we can directly attack the fundamental question of the reason for the dichotomy.

IMAP↗