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At least 1,063 records · Page 59Linked to original sources

USGS2026

Impacts of transient critical zone evolution on landslide susceptibility and hazard Across the Utuado batholith, Puerto Rico

Landscapes in humid climates often experience rapid chemical and mechanical weathering that can change groundwater fluxes, drainage pathways, and frictional strength via alterations in subsurface mineral composition and matrix porosity. These changes to hillslope critical zone structure and strength should control landslide susceptibility, size, and failure style. Here we test the impact of differential weathering on landslide failure processes by exploiting a natural experiment along the dioritic Utuado batholith in Puerto Rico's Cordillera Central, where a sharp weathering gradient follows an upstream-propagating knickzone into an uplifted shoreline platform that was affected by Hurricane Maria in 2017. Through a combination of landslide mapping, field geophysical and geotechnical surveys, topographic analysis, calibrated stream profile inversion, 3D back-analysis of hillslope strength, and debris-flow inundation assessments, we show that differential weathering induces changes to critical zone structure and consequently landslide susceptibility and hazard. Our mapping reveals that the hurricane-induced landslides preferentially cluster along less weathered hillslopes despite a marked increase in frictional strength. Jointly inverted seismic refraction and electrical resistivity profiles show that the frictionally weak, heavily weathered hillslopes are highly porous and dry, which we posit acts to stabilize slopes through limiting deeper hydrologic connectivity that can produce shallow water tables with destabilizing lateral seepage forces during storms. Debris-flow inundation mapping and analysis reveals that major contributors to debris-flow growth, channel steepness and landslide coalescence, scale linearly with hillslope friction angle. This leads to higher-mobility debris flows along knickzone reaches, which disproportionately affects communities at the base of the plateau.

Puerto Rico↗

USGS1983

Summary of workshops concerning regional seismic source zones of parts of the conterminous United States, convened by the U.S. Geological Survey, 1979-1980, Golden, Colorado

Workshops were convened by the U.S. Geological Survey to obtain the latest information and concepts relative to defining seismic source zones for five regions of the United States. The zones, with some modifications, have been used in preparation of new national probabilistic ground motion hazard maps by the U.S. Geological Survey. The five regions addressed are the Great Basin, the Northern Rocky Mountains, the Southern Rocky Mountains, the Central Interior, and the northeastern United States. Discussions at the workshops focussed on possible temporal and spatial variations of seismicity within the regions, latest ages of surface-fault displacements, most recent uplift or subsidence, geologic structural provinces as they relate to seismicity, and speculation on earthquake causes. Within the Great Basin region, the zones conform to areas characterized by a predominance of faults that have certain ages of latest surface displacements. In the Northern and Southern Rocky Mountain regions, zones primarily conform to distinctive structural terrane. In the Central Interior, primary emphasis was placed on an interpretation of the areal distribution of historic seismicity, although geophysical studies in the Reelfoot rift area provided data for defining zones in the New Madrid earthquake area. An interpretation of the historic seismicity also provided the basis for drawing the zones of the New England region. Estimates of earthquake maximum magnitudes and of recurrence times for these earthquakes are given for most of the zones and are based on either geologic data or opinion.

Circular↗

USGS2007

Morphological evolution in the San Francisco Bight

San Francisco Bight, located near the coast of San Francisco, USA, is an extremely dynamic tidal inlet environmental subject to large waves and strong currents. Wave heights coming from the Pacific Ocean commonly exceed 5 m during winter storms. During peak flow tidal currents approach 3 m/s at the Golden Gate, a 1 km wide entrance that connects San Francisco Bay to the Pacific Ocean. Flow structure in this region varies markedly spatially and temporally due to the complex interaction by wind, waves and tidal currents. A multibeam sonar survey was recently completed that mapped in high resolution, for the first time, the bottom morphology in the region of the ebb tidal delta. This data set includes a giant sand wave field covering an area of approximately 4 square kilometers. The new survey enables the calculation of seabed change that has occurred in the past 50 years, since the last comprehensive survey of the area was completed. This comparison indicates an average erosion of 60 centimeters which equates to a total volume change of approximately 9.3 x 10 7 m 3 . Morphologic change also indicates that flood channels have filled and that the entire ebb delta is contracting radially.

California↗

USGS1988

Aeromagnetic maps of the Colorado River region including the Kingman, Needles, Salton Sea, and El Centro 1 degree by 2 degrees quadrangles, California, Arizona, and Nevada

Aeromagnetic data for the Colorado river region have been compiled as part of the Pacific to Arizona Crustal Experiment (PACE) Project. The data are presented here in a series of six compilations for the Kingman, Needles, Salton Sea, and El Centro 1 degree by 2 degree quadrangles, California, Arizona, and Nevada, at scales of 1:250,000 and 1:750,000. The scales and map areas are identical to those used by Mariano and others (1986) to display the Bouguer and isotatic residual gravity for this region. Data were compiled separately for the Kingman quadrangle, the Needles quadrangle, and an area covering the Salton Sea quadrangle and part of the El Centro quadrangle. Aeromagnetic anomalies are produced by variations in the strength and direction of the magnetic field of rocks that include magnetic minerals, commonly magnetite. Patterns of anomalies on aeromagnetic maps can reveal structures - for example, faults which have juxtaposed magnetic rocks against non-magnetic rocks, or areas of alteration where magnetic minerals have been destroyed by hydrothermal activity. Tectonic features of regional extent may not become apparent until a number of aeromagnetic surveys have been compiled and plotted at the same scale. Commonly the compilation involves piecing together data from surveys that were flown at different times with widely disparate flight specifications and data reduction procedures. The data may be compiled into a composite map, where all the pieces are plotted onto one map without regard to the difference in flight elevation and datum, or they may be compiled into a merged map, where all survey data are analytically reduced to a common flight elevation and datum, and then digitally merged at the survey boundaries. The composite map retains the original resolution of all the survey data, but computer methods to enhance regional features crossing the survey boundaries may not be applied. On the other hand, computer methods can be applied to the merged data, but the accuracy of the data may be slightly diminished.

Arizona, California, Nevada↗

USGS1980

Preliminary aeromagnetic map of the Charlotte 1 x 2 degree quadrangle, North Carolina, South Carolina

The aeromagnetic map of the Charlotte 1 x 2 degree quadrangle was assembled by 6 individual detailed aeromagnetic surveys flown between 1956 and 1976 (see index map). The International Geomagnetic Reference Field had been subtracted from the data prior to assembly. An arbitrary common datum was selected and the surveys were recontoured at the joins. The 100 gamma contour was selected because it shows the magnetic contrast to best advantage. To complement the magnetic data a gravity survey was conducted by the U.S. Geological Survey and this data is available in a companion map (Wilson and Daniels, in press). Each of these maps has been interpreted in relation to the other and to the geologic map prepared as part of the same program (Goldsmith and others, 1978). It should be noted that the geophysics has had a measurable influence on some of the geologic mapping.

North Carolina, South Carolina↗

USGS2002

Cruise report RV Moana Wave Cruise M-1-02-GM bathymetry and acoustic backscatter of the mid and outer continental shelf, head of De Soto Canyon, northeastern Gulf of Mexico June 17, through July 9, 2002 Pensacola, FL to Pensacola, FL

The mid to outer continental shelf off Mississippi-Alabama and off northwest Florida were the focus of US Geological Survey (USGS) multibeam echosounder (MBES) mapping cruises in 2000 and 2001, respectively. These areas were mapped to investigate the extent of "deep-water reefs" first suggested by Ludwick and Walton (1957). The reefs off Mississippi and Alabama were initially described in water depths of 60 to 120 m (Ludwick and Walton, 1957) but the 2000 mapping found reef and hardgrounds to be much more extensive than previously thought (Gardner et al., 2001). The persistent trend of reef-like features along the outer shelf of Mississippi-Alabama suggested the trend might continue along the northwest Florida mid and outer shelf so a MBES-mapping effort was mounted in 2001 to test this suggestion. It is critical to determine the accurate location, geomorphology, and types of the ridges and reefs that occur in this region to understand the Quaternary history of the area and to assess their importance as benthic habitats for fisheries. The 2001 survey found a series of shelf-depth platforms with ridges (possibly reefs) constructed on their surfaces (Gardner et al., 2002). The area known as the "head of De Soto Canyon" is the large unmapped region between the 2000 and 2001 mapped areas. The head of De Soto Canyon is an outer shelf zone with a relatively steep western wall and a much gentler eastern wall. It was unknown prior to this cruise whether the reefs of the Mississippi-Alabama shelf continue eastward into the head of De Soto Canyon and connect with the ridges and reefs mapped on the northwest Florida outer shelf. The existence of carbonate-cemented latest Quaternary to Holocene sandstones along the western wall of the head of De Soto Canyon (Shipp and Hopkins, 1978; Benson et al., 1997; W.W. Schroeder, personnel comm., 2002) is of interest because of the potential benthic habitats they may represent. Precisely georeferenced high-resolution mapping of bathymetry is a fundamental first step in the study of an area suspected to be critical benthic habitats. Morphology is thought to be critical to define the distribution of dominant demersal plankton/planktivores communities. Community structure and trophodynamics of demersal fishes of the outer continental shelf of the northeastern Gulf of Mexico presently are focuses of a major USGS research project. A goal of the project is to answer questions concerning the relative roles played by morphology and surficial geology in controlling biological differentiation. Deep-water ridges, reefs, and outcrops are important because they are fish havens and key spawning sites, and are critical habitats for larval, juvenile, and economically important sport/food fishes.

Gulf of Mexico, head Of De Soto Canyon↗

USGS1984

Index for reports released through the Department of Energy, DOE National Uranium Resource Evaluation Program, and Atomic Energy Commission

The U.S. Government's National Uranium Resource Evaluation (NURE) Program commenced in 1974 and was last comprehensively reported on in An Assessment Report on Uranium in the United States of America , GJO-111(80), dated October 1980. During the seven years of the NURE Program, an unprecedented quantity of geoscience information was gathered throughout the conterminous United States and Alaska. The resulting data bases in geology, geophysics, and geochemistry are substantial and can be applied to the search for many mineral resource commodities other than uranium. This paper describes briefly what data are available, where the data are located, and how they can be obtained by the public. These data fall into seven major categories: Geologic Quadrangle Maps, Radiometric Data from Aerial Surveys, Magnetic Data from Aerial Surveys, Geochemical Data from Waters and Sediments, Radiometric Data from Borehole Logging, Mineralogic Data from Rock Sample Analysis, Evaluation Data for Resource Estimates. Nearly all the NURE data were acquired, are organized, and can be accessed by National Topographic Map Series (NTMS) 1:250,000-scale quadrangle. Figures 1 and 2 show the distribution of these quadrangles throughout the lower 48 states and Alaska, respectively. Listed below are the 20 repositories scattered across the country where the U.S. Department of Energy (DOE) has placed most of the information on open-file.

Report↗

USGS2011

Bathymetric and sediment facies maps for China Bend and Marcus Flats, Franklin D. Roosevelt Lake, Washington, 2008 and 2009

The U.S. Geological Survey (USGS) created bathymetric and sediment facies maps for portions of two reaches of Lake Roosevelt in support of an interdisciplinary study of white sturgeon (Acipenser transmontanus) and their habitat areas within Franklin D. Roosevelt Lake, Washington. In October 2008, scientists from the USGS used a boat-mounted multibeam echo sounder (MBES) to describe bathymetric data to characterize surface relief at China Bend and Marcus Flats, between Northport and Kettle Falls, Washington. In March 2009, an underwater video camera was used to view and record sediment facies that were then characterized by sediment type, grain size, and areas of sand deposition. Smelter slag has been identified as having the characteristics of sand-sized black particles; the two non-invasive surveys attempted to identify areas containing black-colored particulate matter that may be elements and minerals, organic material, or slag. The white sturgeon population in Lake Roosevelt is threatened by the failure of natural recruitment, resulting in a native population that consists primarily of aging fish and that is gradually declining as fish die and are not replaced by nonhatchery reared juvenile fish. These fish spawn and rear in the riverine and upper reservoir reaches where smelter slag is present in the sediment of the river lake bed. Effects of slag on the white sturgeon population in Lake Roosevelt are largely unknown. Two recent studies demonstrated that copper and other metals are mobilized from slag in aqueous environments with concentrations of copper and zinc in bed sediments reaching levels of 10,000 and 30,000 mg/kg due to the presence of smelter slag. Copper was found to be highly toxic to 30-day-old white sturgeon with 96-h LC50 concentrations ranging from 3 to 5 (u or mu)g copper per liter. Older juvenile and adult sturgeons commonly ingest substantial amounts of sediment while foraging. Future study efforts in Lake Roosevelt should include sampling of bottom material to confirm the presence or absence of slag material indicated on the map. In addition, follow-up acoustic work to determine stream velocities at varying discharges, in conjunction with sediment mapping, would be helpful to more accurately identify areas of scour and areas of sediment deposition where slag deposits may accumulate within the Marcus Flats and China Bend reaches. MBES mapping could also be used to determine changes in bed elevation and sedimentation in the study reaches and could help evaluate annual deposition and provide estimates on fine-sediment thickness.

Washington↗

USGS2001

Geologic Map of the House Rock Quadrangle, Coconino County, Northern Arizona

This digital map database is compiled from unpublished data and new mapping by the authors, represents the general distribution of surficial and bedrock geology in the mapped area. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area. The database dilineate map units that are identified by age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:24,000 or smaller.

Miscellaneous Field Studies Map↗

USGS2001

Geologic Map of the Cane Quadrangle, Coconino County, Northern Arizona

This digital map database is compiled from unpublished data and new mapping by the authors, represents the general distribution of surficial and bedrock geology in the mapped area. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area. The database delineate map units that are identified by age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:24,000 or smaller.

Miscellaneous Field Studies Map↗

USGS2001

Geologic Map of the House Rock Spring Quadrangle, Coconino County, Northern Arizona

This digital map database is compiled from unpublished data and new mapping by the authors, represents the general distribution of surficial and bedrock geology in the mapped area. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area. The database delineate map units that are identified by age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:24,000 or smaller.

Miscellaneous Field Studies Map↗

USGS2002

Geologic map of the Hidden Hills and vicinity, Mohave County, northwestern Arizona

This digital map database is compiled from unpublished data and new mapping by the authors and represents the general distribution of surficial and bedrock geology in the mapped area. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area. The database delineates map units that are identified by age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:31,680 or smaller.

Arizona↗

USGS2002

Geologic map of Clayhole Wash and vicinity, Mohave County, northwestern Arizona

This digital map database is compiled from unpublished data and new mapping by the authors and represents the general distribution of surficial and bedrock geology in the mapped area. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area. The database dilineates map units that are identified by age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:31,680 or smaller.

Miscellaneous Field Studies Map↗

USGS2003

Geologic map of the Lower Hurricane Wash and vicinity, Mohave County, Northwestern Arizona

This digital map database is compiled from published open file reports, and new mapping by the author, and represents the general distribution of surficial and bedrock geology in the mapped area. The map area lies within the Shivwits and Uinkaret Plateaus, subplateaus of the southwestern part of the Colorado Plateau hypsographic province. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area. The database delineates map units that are identified by age and lithology, following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:31,680 or smaller.

Miscellaneous Field Studies Map↗

USGS2003

Geologic map of the Upper Hurricane Wash and vicinity, Mohave County, northwestern Arizona

This digital map database is compiled from unpublished open file reports by the author and represents the general distribution of surficial and bedrock geology in the mapped area. The map area lies within the Shivwits and Uikaret Plateaus, together with the accompanying pamphlet, it provides current information on the geologic structure, stratigraph, and Cenozoic geology of the area. The database delineates map units that are identified by age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:31,680 or smaller.

Miscellaneous Field Studies Map↗

USGS2003

Geologic map of upper Clayhole Valley and vicinity, Mohave County, northwestern Arizona

Miscellaneous Field Studies Map↗

USGS2004

Geologic map of the Lower Grand Wash cliffs and vicinity, Mohave County, Northwestern Arizona

This digital map database is compiled from unpublished data and new mapping by the authors and represents the general distribution of surficial and bedrock geology in the mapped area. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area. The database dilineates map units that are identified by age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution of the database to 1:31,680 or smaller.

Miscellaneous Field Studies Map↗

USGS2013

Coal fields of the conterminous United States—National Coal Resource Assessment updated version

This map sheet with accompanying Geographic Information System (GIS) project is an update of the existing U.S. Geological Survey (USGS) Conterminous U.S. Coal Fields map. This update was compiled using data primarily from the USGS National Coal Resource Assessment (NCRA) and information from other published maps. The five regions examined by NCRA (Eastern, Gulf Coast, Interior, Rocky Mountain, and Northern Great Plains) constituted 93 percent of U.S. coal production at the time of the assessments. The map sheet shows aerial extent, rank, province, name (region and field), and age information, which are also attributes of the GIS project. Due to changing technological and economic constraints for coal usage, along with the potential for geologic carbon dioxide sequestration, this map sheet and the GIS component of this report do not differentiate between potentially minable coal and uneconomic coal. Additional figures on the map sheet show coal formations, current production by State, coal rank definitions, and charts showing historical trends of coal production.

Open-File Report↗