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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 901 records · Page 50Linked to original sources

USGS2014

Geospatial compilation of historical water-level changes in the Chicot and Evangeline aquifers 1977-2013 and Jasper aquifer 2000-13, Gulf Coast aquifer system, Houston-Galveston region, Texas

The U.S. Geological Survey (USGS) in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District has produced an annual series of reports that depict water-level changes in the Chicot, Evangeline, and Jasper aquifers of the Gulf Coast aquifer system in the Houston-Galveston region, Texas, from 1977 to 2013. Changes are determined from water-level measurements between December and March of each year from groundwater wells screened in one of the three aquifers. Existing published maps and unpublished geographic information system (GIS) datasets were compiled into a comprehensive geodatabase of all water-level-change maps produced as part of this multiagency effort. Annual water-level-change maps were georeferenced and digitized where existing GIS data were unavailable (1979–99). Existing GIS data available for 2000–13 were included in the geodatabase. The compilation contains 121 datasets showing water-level changes for each primary aquifer of the Gulf Coast aquifer system: 56 for the Chicot aquifer (1977; 1979–2013 and 1990; 1993–2013), 56 for the Evangeline aquifer (1977; 1979–2013 and 1990; 1993–2013), and 9 for the Jasper aquifer (2000; 2005–13).

Texas↗

USGS2002

Thermal maturity patterns (CAI and %Ro) in the Ordovician and Devonian rocks of the Appalachian basin in Pennsylvania

This report presents a series of new thermal maturation maps for Pennsylvania, based on conodont color alteration index (CAI) and vitrinite reflectance (%R o ). Also, RockEval and total organic carbon (TOC) data are included in the report. Two Paleozoic intervals were studied: Middle Ordovician carbonate rocks and Lower and Middle Devonian carbonate rocks and black shale. These intervals were chosen for several reasons: A) they represent target reservoir zones for most of the oil and gas exploration and drilling in Pennsylvania; B) they are stratigraphically near probable source rocks for the oil and gas; C) they include contiguous geologic formations that extend across most of Pennsylvania; D) they contain carbonate grainstone/packstone which give a reasonable to good probability of recovery of conodont elements from small samples of drill cuttings; and E) the Middle Devonian black shale contains large amounts of organic matter for geochemical analysis.

Pennsylvania↗

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↗

USGS2018

Breaching of strike-slip faults and successive flooding of pull-apart basins to form the Gulf of California seaway from ca. 8–6 Ma

The geologic record of the formation of marine basins during continental rifting is uncommonly preserved. Using GIS-based paleotectonic maps, we show that marine basin formation in the Gulf of California–Salton trough oblique rift (Mexico and the United States) occurred in a stepwise manner as crustal thinning lowered elevations within the Gulf of California Shear Zone, and subsidence along strike-slip and transtensional faults linked isolated pull-apart basins. At 8 Ma, the earliest marine conditions in the Gulf of California were restricted to an embayment at its southern mouth. Farther north, the plate boundary was a set of continental strike-slip faults and linked pull-apart basins, similar to the modern Walker Lane in Nevada and California. By ca. 7 Ma, a series of marine incursions breached across strike-slip faults to the Pescadero and Farallon basins. Marine waters then breached a 75–100 km-long transtensional fault zone between the Farallon and Guaymas basins, with intermittent flooding that led to accumulation of extensive evaporite deposits in the Guaymas basin. Marine incursion north of the Guaymas basin via breaches across the Guaymas and Tiburón strike-slip faults and transtensional zones resulted in flooding of the northern >500 km of the oblique rift by 6.5–6.3 Ma. Thus, strike-slip and transtensional faulting promoted localization of plate boundary strain and guided punctuated marine flooding of the Gulf of California seaway. Inception of the narrow, 1500-km-long Gulf of California at ca. 6.3 Ma was followed by complete continental rupture in the Guaymas basin at ca. 6.0 Ma.

Geology↗

USGS2014

Archive of single-beam bathymetry data collected from select areas in Weeks Bay and Weeks Bayou, southwest Louisiana, January 2013

A team of scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, collected 92 line-kilometers of dual-frequency single-beam bathymetry data in the tidal creeks, bayous, and coastal areas near Weeks Bay, southwest Louisiana. Limited bathymetry data exist for these tidally and meteorologically influenced shallow-water estuarine environments. In order to reduce the present knowledge gap, the objectives of this study were to (1) develop methods for regional inland bathymetry mapping and monitoring, (2) test inland bathymetry mapping system in pilot locations for integrating multiple elevation (aerial and terrestrial lidar) and bathymetry datasets, (3) implement inland bathymetry mapping and monitoring in highly focused sites, and (4) evaluate changes in bathymetry and channel-fill sediment storage using these methods. This report contains single-beam bathymetric data collected between January 14 and 18, 2013. Data were collected from the RV Mako (5-meter vessel) in water depths that ranged from <1 meter to 7.7 meters. Locations of data collection ranged from open-bay systems to narrow inland tidal creeks (U.S. Geological Survey Field Activity Number 13CCT01). This report serves as an archive of processed bathymetry data. Geographic information system data provided in this document include a 10-meter cell-size interpolated gridded bathymetry surface, and trackline maps. Additional files include error analysis maps, Field Activity Collection System logs, and formal Federal Geographic Data Committee metadata. Do not use these data for navigational purposes.

Louisiana↗

USGS2015

Geologic map of the Alamosa 30’ × 60’ quadrangle, south-central Colorado

The Alamosa 30'× 60' quadrangle is located in the central San Luis Basin of southern Colorado and is bisected by the Rio Grande. The Rio Grande has headwaters in the San Juan Mountains of Colorado and ultimately discharges into the Gulf of Mexico 3,000 kilometers (km) downstream. Alluvial floodplains and associated deposits of the Rio Grande and east-draining tributaries, La Jara Creek and Conejos River, occupy the north-central and northwestern part of the map area. Alluvial deposits of west-draining Rio Grande tributaries, Culebra and Costilla Creeks, bound the Costilla Plain in the south-central part of the map area. The San Luis Hills, a northeast-trending series of flat-topped mesas and hills, dominate the landscape in the central and southwestern part of the map and preserve fault-bound Neogene basin surfaces and deposits. The Precambrian-cored Sangre de Cristo Mountains rise to an elevation of nearly 4,300 meters (m), almost 2,000 m above the valley floor, in the eastern part of the map area. In total, the map area contains deposits that record surficial, tectonic, sedimentary, volcanic, magmatic, and metamorphic processes over the past 1.7 billion years.

Colorado↗

USGS2020

Northward migration of the Oregon forearc on the Gales Creek fault

The Gales Creek fault (GCF) is a 60-km-long, northwest-striking dextral fault system (west of Portland, Oregon) that accommodates northward motion and uplift of the Oregon Coast Range. New geologic mapping and geophysical models confirm inferred offsets from earlier geophysical surveys and document ∼12 km of right-lateral offset of a basement high in Eocene Siletz River Volcanics since ca. 35 Ma and ∼8.8 km of right-lateral separation of Miocene Columbia River Basalt at Newberg, Oregon, since 15 Ma (∼0.62 ± 0.12 mm/yr, average long-term rate). Relative uplift of Eocene Coast Range basalt basement west of the fault zone is at least 5 km based on depth to basement under the Tualatin Basin from a recent inversion of gravity data. West of the city of Forest Grove, the fault consists of two subparallel strands ∼7 km apart. The westernmost, Parsons Creek strand, forms a linear valley southward to Henry Hagg Lake, where it continues southward to Newberg as a series of en echelon strands forming both extensional and compressive step-overs. Compressive step-overs in the GCF occur at intersections with ESE-striking sinistral faults crossing the Coast Range, suggesting the GCF is the eastern boundary of an R′ Riedel shear domain that could accommodate up to half of the ∼45° of post–40 Ma clockwise rotation of the Coast Range documented by paleomagnetic studies. Gravity and magnetic anomalies suggest the western strands of the GCF extend southward beneath Newberg into the Northern Willamette Valley, where colinear magnetic anomalies have been correlated with the Mount Angel fault, the proposed source of the 1993 M 5.7 Scotts Mills earthquake. The potential-field data and water-well data also indicate the eastern, Gales Creek strand of the fault may link to the NNW-striking Canby fault through the E-W Beaverton fault to form a 30-km-wide compressive step-over along the south side of the Tualatin Basin. LiDAR data reveal right-lateral stream offsets of as much as 1.5 km, shutter ridges, and other youthful geomorphic features for 60 km along the geophysical and geologic trace of the GCF north of Newberg, Oregon. Paleoseismic trenches document Eocene bedrock thrust over 250 ka surficial deposits along a reverse splay of the fault system near Yamhill, Oregon, and Holocene motion has been recently documented on the GCF along Scoggins Creek and Parsons Creek. The GCF could produce earthquakes in excess of Mw 7, if the entire 60 km segment ruptured in one earthquake. The apparent subsurface links of the GCF to other faults in the Northern Willamette Valley suggest that other faults in the system may also be active.

Oregon↗

USGS2006

Proceedings of the U.S. Geological Survey Sixth Biennial Geographic Information Science Workshop, Denver, Colorado, April 24-28, 2006

The U.S. Geological Survey's (USGS) Sixth Biennial Geographic Information Science Workshop April 24 - 28, 2006, at the Denver Federal Center in Denver, Colorado, provides a unique opportunity for multi-disciplinary Geographic Information Systems (GIS) and associated scientific professionals to share, learn, present, and discuss a wide variety of geospatial-related topics. Information is exchanged through a series of plenary sessions, hands-on technical workshops, user and commercial vendor demonstrations, lecture and poster sessions, and specialty meetings. Workshop attendance is limited to Department of Interior (DOI) and USGS employees and contractors; however, plenary, hands-on, and lecture sessions have presenters from other Federal agencies, numerous commercial vendors, universities, and several consortia. Over 175 participants are expected to attend the Workshop. Several prominent speakers are featured at this Workshop. Monday evening Star Guest Speaker and National Aeronautics and Space Administration (NASA) Astronaut Captain Dominic Gorie will talk about his experiences as a veteran of three space flights and over 32 days in space, including the NASA Space Shuttle Radar Topography Mission that mapped more than 47 million miles of the Earth's land surface. Selected as an astronaut candidate by NASA in December 1994, Captain Gorie is currently Chief of the Astronaut Shuttle Branch. Monday evening also features a town hall meeting with Geographic Information Office (GIO) leaders Karen Siderelis, Kevin Gallagher, Bob Pierce, Steve Guptill, Mark DeMulder, John Mahoney, and Mark Negri, who will discuss changes and activities within the GIO in an open discussion format. Tuesday plenary sessions feature keynote speaker Dr. P. Patrick Leahy, Acting USGS Director. Dr. Leahy holds undergraduate and graduate degrees in geology (1968) and geophysics (1970) from Boston College. In 1979, he received his doctorate in geology from Rensselaer Polytechnic Institute, where he specialized in regional ground-water studies and hydraulics. Dr. Leahy has been with the USGS since 1974, and has held various technical and managerial positions, including Associate Director for Geology and Chief of the National Water-Quality Assessment (NAWQA) Program. Dr. Leahy will be discussing a broad range of topics including Bureau accomplishments, initiatives, and budgets. The purpose of this proceedings volume is to serve as an activity reference for Workshop attendees as well as an archive of technical abstracts submitted, presented, and discussed at the Workshop. Author, co-author, and presenter names, affiliations, and contact information are listed with presentation titles along with submitted abstracts. Some hands-on sessions are offered twice. In these instances, abstracts submitted for publication are presented in the proceedings on both days they are offered. All acronyms used in these proceedings are explained in the text of each abstract. The term 'ArcGIS' refers to an integrated collection of GIS software products produced by Environmental Systems Research Institute, Inc. (ESRI).

Scientific Investigations Report↗

USGS1999

Transcontinental arch - a pattern formed by rejuvenation of local features across central North America

The transcontinental Arch has been described by many authors as a feature having significant tectonic influence during the Phanerozoic, although the location, magnitude, and even the timing defining the arch vary greatly among authors. The general trend usually suggested for the Transcontinental Arch is northeast-southwest across the western midcontinent of North America. A series of isopachous and paleogeologic maps was compiled for this study that defines a number of smaller tectonic features - commonly trending northwest-southeast. Six persistent highs and six persistent lows (or sags) are defined that are largely basement controlled and were rejuvenated at various times during the Phanerozoic. These smaller northwest-trending features, when taken collectively and enhanced by the relative downwarping of the adjacent Williston and Anadarko basins, create a platform-like feature - the Transcontinental Arch of the literature. The concept of a Transcontinental Arch is an important reference trend in the geologic history of North America. In both regional and local studies, however, the smaller-scale, transverse features may have had significant control on both tectonic patterns and depositional influence.

Tectonophysics↗

USGS2009

Database of the geologic map of North America— Adapted from the map by J.C. Reed, Jr. and others (2005)

Introduction The Geological Society of America's (GSA) Geologic Map of North America (Reed and others, 2005a; 1:5,000,000) shows the geology of a significantly large area of the Earth, centered on North and Central America and including the submarine geology of parts of the Atlantic and Pacific Oceans. This map is now converted to a Geographic Information System (GIS) database that contains all geologic and base-map information shown on the two printed map sheets and the accompanying explanation sheet. We anticipate this map database will be revised at some unspecified time in the future, likely through the actions of a steering committee managed by the GSA and staffed by scientists from agencies including those responsible for the original map compilation. Regarding the use of this product, as noted by the map's compilers: “The Geologic Map of North America is an essential educational tool for teaching the geology of North America to university students and for the continuing education of professional geologists in North America and elsewhere. In addition, simplified maps derived from the Geologic Map of North America are useful for enlightening younger students and the general public about the geology of the continent.” With publication of this database, the preparation of any type of simplified map is made significantly easier. More important perhaps, the database provides a more accessible means to explore the map information and to compare and analyze it in conjunction with other types of information (for example, land use, soils, biology) to better understand the complex interrelations among factors that affect Earth resources, hazards, ecosystems, and climate.

Data Series↗

USGS2008

Archive of digitized analog boomer seismic reflection data collected from Lake Pontchartrain, Louisiana, to Mobile Bay, Alabama, during cruises onboard the R/V ERDA-1, June and August 1992

In June and August of 1992, the U.S. Geological Survey (USGS) conducted geophysical surveys to investigate the shallow geologic framework from Lake Pontchartrain, Louisiana, to Mobile Bay, Alabama. This work was conducted onboard the Argonne National Laboratory's R/V ERDA-1 as part of the Mississippi/Alabama Pollution Project. This report is part of a series to digitally archive the legacy analog data collected from the Mississippi-Alabama SHelf (MASH). The MASH data rescue project is a cooperative effort by the USGS and the Minerals Management Service (MMS). A standardized naming convention was established to allow for better management of scanned trackline images within the MASH data rescue project. Each cruise received a unique field activity ID based on the year the data were collected, the first two digits of the survey vessel name, and the number of cruises made (to date) by that vessel that year (i.e. 92ER2 represents the second cruise made by the R/V ERDA-1 in 1992.) The new field activity IDs 92ER2 and 92ER4 presented in this report were originally referred to as ERDA 92-2 and ERDA 92-4 at the USGS in St. Petersburg, FL, and 92010 and 92037 at the USGS in Woods Hole, MA. A table showing the naming convention lineage for cruise IDs in the MASH data rescue series is included as a PDF. This report serves as an archive of high resolution scanned Tagged Image File Format (TIFF) and Graphics Interchange Format (GIF) images of the original boomer paper records, navigation files, trackline maps, Geographic Information System (GIS) files, cruise logs, and formal Federal Geographic Data Committee (FGDC) metadata for cruises 92ER2 and 92ER4. The boomer system uses an acoustic energy source called a plate, which consists of capacitors charged to a high voltage and discharged through a transducer in the water. The source is towed on a sled, at sea level, and when discharged emits a short acoustic pulse, or shot, which propagates through the water and sediment column. The acoustic energy is reflected at density boundaries (such as the seafloor or sediment layers beneath the seafloor), detected by the hydrophone receiver, and the amplitude of the reflected energy is recorded by an Edward P. Curley Lab (EPC) thermal plotter. This process is repeated at timed intervals (for example, 0.5 s) and recorded for specific intervals of time (for example, 100 ms). The timed intervals are also referred to as the shot interval or fire rate. On analog records, the recorded interval is referred to as the sweep, which is the amount of time the recorder stylus takes to sweep from the top of the record to the bottom of the record, thereby recording the amplitude of the reflected energy of one shot. In this way, consecutive recorded shots produce a two-dimensional (2-D) vertical image of the shallow geologic structure beneath the ship track. Many of the geophysical data collected by the USGS prior to the late 1990s were recorded in analog format and stored as paper copies. Scientists onboard made hand-written annotations onto these records to note latitude and longitude, time, line number, course heading, and geographic points of reference. Each paper roll typically contained numerous survey lines and could reach more than 90 ft in length. All rolls are stored at the USGS FISC-St. Petersburg, FL. To preserve the integrity of these records and improve accessibility, analog holdings were converted to digital files.

Alabama, Louisiana, Mississippi↗

USGS1988

Major ground-water flow systems in the Great Basin region of Nevada, Utah, and adjacent states

This atlas is one of several reports that are products of an analysis of regional aquifer systems in the Great Basin of Nevada, Utah, and adjacent States. The Geological Survey program of regional aquifer-system analyses is a nationwide study of ground-water systems on a regional scale. The program is intended to establish a framework of geologic, hydrologic, and geochemical information for each regional aquifer system studied. As of 1985, studies have been started or completed in 19 areas. The scope of the Great Basin Regional Aquifer-System Analysis is outlined by Harrill and others (1983). The purpose of this report is to bring the findings of several studies together into a map report that discusses regional aspects of ground-water flow in the Great Basin, delineates the major ground-water flow systems, and briefly describes some of their characteristics. This atlas is Chapter C of a three-part series. Chapter A delineates and describes hydrogeologic units in the Great Basin region, and Chapter B shows the generalized distribution of hydraulic potential.

Nevada, Utah↗

USGS1992

Geohydrologic systems in Kansas: Physical framework of the upper aquifer unit in the western interior plains aquifer system

The purpose of this Hydrologic Investigations Atlas is to provide a description of the principal geohydrologic systems in Upper Cambrian through Lower Cretaceous rocks in Kansas. This investigation was made as part of the Central Midwest Regional Aquifer-System Analysis (CMRASA). The CMRASA is one of several major investigations by the U.S. Geological Survey of regional aquifer systems in the United States. These regional investigations are designed to increase knowledge of the flow regime and hydrologic properties of major aquifer systems and to provide quantitative information for the assessment, development, and management water supplies. The CMRASA study area includes all or parts of 10 Central Midwestern States (Jorgensen and Signor, 1981), as shown on the envelope cover. This Hydrologic Investigations Atlas, which consists of a series of nine chapters, presents a description of the physical framework and the geohydrology of principal aquifers and confining systems in Kansas. Chapter D presents maps that show the areal extent, altitude and configuration of the top, and thickness of Mississippian rocks that compose the upper aquifer unit of the Western Interior Plains aquifer system in Kansas, The chapter is limited to the presentation of the physical framework of the upper aquifer unit. The interpretation of the physical framework of the upper aquifer unit is based on selected geophysical and lithologic logs and published maps of stratigraphically equivalent units. Maps indicating the thickness and the altitude and configuration of the top of the upper aquifer unit in the Western Interior Plains aquifer system have been prepared as part of a series of interrelated maps that describe the stratigraphic interval from the Precambrian basement through Lower Cretaceous rocks. A concerted effort was made to ensure that maps of each geohydrologic unit are consistent with the maps of underlying and overlying units. Chapter A of this atlas series (Wolf and others, 1990) describes the relation of principal geohydrologic systems in Kansas and presents a more detailed discussion of the methods and data used to prepare and ensure consistency among the sets of maps.

Kansas↗

USGS2008

Predicted surface displacements for scenario earthquakes in the San Francisco Bay region

In the immediate aftermath of a major earthquake, the U.S. Geological Survey (USGS) will be called upon to provide information on the characteristics of the event to emergency responders and the media. One such piece of information is the expected surface displacement due to the earthquake. In conducting probabilistic hazard analyses for the San Francisco Bay Region, the Working Group on California Earthquake Probabilities (WGCEP) identified a series of scenario earthquakes involving the major faults of the region, and these were used in their 2003 report (hereafter referred to as WG03) and the recently released 2008 Uniform California Earthquake Rupture Forecast (UCERF). Here I present a collection of maps depicting the expected surface displacement resulting from those scenario earthquakes. The USGS has conducted frequent Global Positioning System (GPS) surveys throughout northern California for nearly two decades, generating a solid baseline of interseismic measurements. Following an earthquake, temporary GPS deployments at these sites will be important to augment the spatial coverage provided by continuous GPS sites for recording postseismic deformation, as will the acquisition of Interferometric Synthetic Aperture Radar (InSAR) scenes. The information provided in this report allows one to anticipate, for a given event, where the largest displacements are likely to occur. This information is valuable both for assessing the need for further spatial densification of GPS coverage before an event and prioritizing sites to resurvey and InSAR data to acquire in the immediate aftermath of the earthquake. In addition, these maps are envisioned to be a resource for scientists in communicating with emergency responders and members of the press, particularly during the time immediately after a major earthquake before displacements recorded by continuous GPS stations are available.

Open-File Report↗

USGS2016

Enriching the national map database for multi-scale use: Introducing the visibilityfilter attribution

The US Geological Survey’s (USGS) National Geospatial Technical Operations Center is prototyping and evaluating the ability to filter data through a range of scales using 1:24,000-scale The National Map (TNM) datasets as the source. A “VisibilityFilter” attribute is under evaluation that can be added to all TNM vector data themes and will permit filtering of data to eight target scales between 1:24,000 and 1:5,000,000, thus defining each feature’s smallest applicable scale-of-use. For a prototype implementation, map specifications for 1:100,000- and 1:250,000-scale USGS Topographic Map Series are being utilized to define feature content appropriate at fixed mapping scales to guide generalization decisions that are documented in a ScaleMaster diagram. This paper defines the VisibilityFilter attribute, the generalization decisions made for each TNM data theme, and how these decisions are embedded into the data to support efficient data filtering.

Conference Paper↗

USGS2011

Database for potential hazards from future volcanic eruptions in California

More than 500 volcanic vents have been identified in the State of California. At least 76 of these vents have erupted, some repeatedly, during the past 10,000 yr. Past volcanic activity has ranged in scale and type from small rhyolitic and basaltic eruptions through large catastrophic rhyolitic eruptions. Sooner or later, volcanoes in California will erupt again, and they could have serious impacts on the health and safety of the State's citizens as well as on its economy. This report describes the nature and probable distribution of potentially hazardous volcanic phenomena and their threat to people and property. It includes hazard-zonation maps that show areas relatively likely to be affected by future eruptions in California. This digital release contains information from maps of potential hazards from future volcanic eruptions in the state of California, published as Plate 1 in U.S. Geological Survey Bulletin 1847. The main component of this digital release is a spatial database prepared using geographic information systems (GIS) applications. This release also contains links to files to view or print the map plate, main report text, and accompanying hazard tables from Bulletin 1847. It should be noted that much has been learned about the ages of eruptive events in the State of California since the publication of Bulletin 1847 in 1989. For the most up to date information on the status of California volcanoes, please refer to the U.S. Geological Survey Volcano Hazards Program website.

California↗

USGS2020

Geomagnetism Program research plan, 2020–2024

The Geomagnetism Program of the U.S. Geological Survey (USGS) monitors geomagnetic field variation through operation of a network of observatories across the United States and its territories, and it pursues scientific research needed to estimate and assess geomagnetic and geoelectric hazards. Over the next five years (2020–2024 inclusive) and in support of national and agency priorities, Geomagnetism Program research scientists plan to pursue an integrated set of research projects broadly encompassing empirical estimation and mapping of geomagnetic disturbance, modeling of solid-Earth conductivity structure and surface impedance, and mapping of magnetic-storm-induced geoelectric fields. Analyses are empirically based, relying on measured time series as well as statistical and numerical modeling of geomagnetic-monitoring data from ground-based observatories and surface-impedance tensors acquired during magnetotelluric surveys. The plan describes augmentation and development of the Geomagnetism Program's existing research portfolio, assuming present funding levels and staffing numbers. Because the projects are interdependent, they cannot be straightforwardly prioritized. They will all be pursued as resources and time permit; additional funding and staffing would enable the projects to be broadened and more rapidly completed. Where appropriate and subject to budgetary constraints and staffing numbers, research on specific projects might be accelerated or even judiciously expanded—some opportunities for expansion are discussed in this plan. Results will provide realistic illumination of the nature of the ground-level expression of space-weather disturbance, a subject of particular importance for projects focused on evaluating the vulnerability of electric-power-grid systems. This plan does not cover Geomagnetism Program operations, which are primarily concerned with the operation of magnetic observatories and, now, magnetotelluric surveys, although the context of such observatories and surveys is discussed. The research element of the program provides guidance for the expansion of program operations and research projects. In addition to the research projects summarized here, program scientists continue to provide leadership to the national and international geomagnetic, magnetotelluric, and space-weather communities.

Circular↗

USGS1986

Potentiometric surface, ground-water withdrawals, and recharge area for the Nanafalia-Clayton aquifer in Alabama, fall 1982

The U.S. Geological Survey began a nationwide program in 1978, termed Regional Aquifer-System Analysis (RASA), to study a number of the major aquifer systems that provide a significant part of the country 's water supply. One of the aquifer systems chosen for study was the thick and extensive sequence of sands for Cretaceous and early Tertiary age that underlies the Coastal Plain of the southeastern United States. This system, which extends from Mississippi eastward to South Carolina, is called the Southeastern Coastal Plain aquifer system. It can be divided geohydrologically into several separate aquifers. This map, one of a series that portray the potentiometric surface, groundwater withdrawal, and recharge areas for the aquifers in Alabama that are included in the regional system, deals with the Nanafalia-Clayton aquifer. (Lantz-PTT)

Water-Resources Investigations Report↗