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At least 163 records · Page 9Linked to original sources
USGS1995

Hydrology and simulation of ground-water flow in southern Utah and Goshen Valleys, Utah

The ground-water resources of southern Utah and Goshen Valleys were assessed from 1988 to 1993 to determine the effects that additional ground-water withdrawals would have on water levels, surface water, and water quality. Recharge, movement, and discharge of ground-water were emphasized. The main ground-water system in southern Utah and Goshen Valleys is in the unconsolidated basin-fill deposits. Recharge to the ground-water system from streams, canals, irrigation, precipitation, intermittent and ephemeral runoff, and subsurface inflow was estimated to be 120,000 acre-feet in southern Utah Valley and 30,000 acre-feet in Goshen Valley in 1990. Discharge from the ground-water system to springs and drains, by evapotranspiration, to wells, streams, canals, Utah Lake, and sewer systems was estimated to be 130,000 acre-feet in southern Utah Valley and 33,000 acre-feet in Goshen Valley in 1990. Release from storage from March 1990 to March 1991 was estimated to be 9,800 acre-feet in southern Utah Valley and 3,400 acre-feet in Goshen Valley. Observed water-level fluctuations indicate that irrigation is not a major source of recharge in either valley and that precipitation is not a major source in Goshen Valley. In southern Utah Valley, water levels in March 1991 were not significantly different from water levels in March 1965. In Goshen Valley, water levels in March 1991 were higher than water levels in March 1965. A three-dimensional, finite-difference, ground-water flow model was used to simulate the ground-water system in the unconsolidated basin-fill deposits of southern Utah and Goshen Valleys. The steady-state conditions of 1949 and annual transient-state conditions from 1949 to 1990 were used to calibrate the model. Model-computed water-level declines of less than 20 feet are projected if municipal well withdrawals increase by 10,000 acre-feet per year. Model-computed water-level declines of 20 feet in southern Utah Valley and 40 to 80 feet in Goshen Valley are projected if well withdrawal is increased by 200 percent of the 1990 withdrawals.

Utah↗
USGS1995

Seepage study of the Sevier River Basin above Sevier Bridge Reservoir, Utah, 1988

A seepage study was done during 1988 on selected reaches of the Sevier River in Utah above Sevier Bridge Reservoir, the East Fork Sevier River in Black Canyon and Kingston Canyon, Long-East Bench and McEwen Canals in the upper Sevier River basin, and the San Pitch River in Sanpete Valley to determine gain or loss of flow from seepage. A net gain occurred in all of the reaches except Kingston Canyon on the East Fork Sevier River, which had a net loss. In the upper Sevier River basin, the Sevier River between Hatch and Circleville Canyon had a net gain of about 125 cubic feet per second; Long-East Bench Canal had a net gain of about 0.7 cubic foot per second; McEwen Canal had a net gain of about 0.9 cubic foot per second; the East Fork Sevier River in Black Canyon had a net gain of about 3.0 cubic feet per second; and the East Fork Sevier River in Kingston Canyon had a net loss of about 8.0 cubic feet per second. In central Sevier Valley, both the south and the north sections had large gains. The net gain for both sections, combined, was about 213 cubic feet per second for August 1988 and about 230 cubic feet per second for October 1988. The reach of the San Pitch River studied had a net gain of about 23.4 cubic feet per second.

Utah↗
USGS1995

Hydrology of Sanpete Valley, Sanpete and Juab Counties, Utah, and simulation of ground-water flow in the valley-fill aquifer

The surface-and ground-water hydrology of Sanpete Valley and the San Pitch River drainage basin, Sanpete and Juab Counties, Utah, was studied to define the current conditions of the hydrologic system, to detect causes for downstream changes in water quality in the San Pitch River and in areas of high concentration of dissolved solids in ground water, and to determine the possible effects of present changes in irrigation methods and possible future increased ground-water withdrawals from the valley-fill aquifer. Measurements of water levels in wells show responses to climatic variation. The dissolved-solids concentration of water from the San Pitch River increases downstream. Principal areas of ground water with high concentrations of dissolved solids occur downgradient from outcrops of rocks of Jurassic and Tertiary age. One local-scale ground-water flow system discharges small volumes of water with high concentrations of dissolved solids to the San Pitch River southwest of Ephraim. Although ground water occurs in both valley-fill and consolidated-rock aquifers in the study area, more hydrologic information is available for the valley-fill aquifer. The valley-fill aquifer consists primarily of fine-grained silt and clay in the center of the valley and coarser deposits along the margin of the valley. Surface- water inflow to the valley is estimated to be about 152,000 acre-feet per year. Recharge to the valley-fill aquifer is estimated to be between 74,000 and 103,000 acre-feet per year. A three-dimensional, ground-water flow model was developed to better define present ground-water conditions and to determine possible effects of future changes in ground-water withdrawals from the valley-fill aquifer. Computer simulation results indicate the possibility of recharge to the valleyfill aquifer as subsurface inflow from consolidated-rock aquifers. Simulation of water-level changes during the late 1980's indicate that some of the declines could have been caused by conversion from flood irrigation to sprinkler irrigation. Predictive simulations using three times the average pumping rates indicate possible water-level declines of as much as 70 feet.

Utah↗
USGS1996

Hydrology and simulation of ground-water flow in Juab Valley, Juab County, Utah.

Plans to import water to Juab Valley, Utah, primarily for irrigation, are part of the Central Utah Project. A better understanding of the hydrology of the valley is needed to help manage the water resources and to develop conjunctive-use plans. The saturated unconsolidated basin-fill deposits form the ground-water system in Juab Valley. Recharge is by seepage from streams, unconsumed irrigation water, and distribution systems; infiltration of precipitation; and subsurface inflow from consolidated rocks that surround the valley. Discharge is by wells, springs, seeps, evapotranspiration, and subsurface outflow to consolidated rocks. Ground-water pumpage is used to supplement surface water for irrigation in most of the valley and has altered the direction of groundwater flow from that of pre-ground-water development time in areas near and in Nephi and Levan. Greater-than-average precipitation during 1980-87 corresponds with a rise in water levels measured in most wells in the valley and the highest water level measured in some wells. Less-than average precipitation during 1988-91 corresponds with a decline in water levels measured during 1988-93 in most wells. Geochemical analyses indicate that the sources of dissolved ions in water sampled from the southern part of the valley are the Arapien Shale, evaporite deposits that occur in the unconsolidated basin-fill deposits, and possibly residual sea water that has undergone evaporation in unconsolidated basin-fill deposits in selected areas. Water discharging from a spring at Burriston Ponds is a mixture of about 70 percent ground water from a hypothesized flow path that extends downgradient from where Salt Creek enters Juab Valley and 30 percent from a hypothesized flow path from the base of the southern Wasatch Range. The ground-water system of Juab Valley was simulated by using the U.S. Geological Survey modular, three-dimensional, finite-difference, ground-water flow model. The numerical model was calibrated to simulate the steady-state conditions of 1949, multi-year transient-state conditions during 1949-92, and seasonal transient-state conditions during 1992-94. Calibration parameters were adjusted until model-computed water levels reasonably matched measured water levels. Parameters important to the calibration process include horizontal hydraulic conductivity, transmissivity, and the spatial distribution and amount of recharge from subsurface inflow and seepage from ephemeral streams to the east side of Juab Valley.

Utah↗
USGS2000

Geohydrology and numerical simulation of groundwater flow in the central Virgin River Basin of Iron and Washington Counties, Utah

Because rapid growth of communities in Washington and Iron Counties, Utah, is expected to cause an increase in the future demand for water resources, a hydrologic investigation was done to better understand ground-water resources within the central Virgin River basin. This study focused on two of the principal ground-water reservoirs within the basin: the upper Ash Creek basin ground-water system and the Navajo and Kayenta aquifer system. The ground-water system of the upper Ash Creek drainage basin consists of three aquifers: the uppermost Quaternary basin-fill aquifer, the Tertiary alluvial-fan aquifer, and the Tertiary Pine Valley monzonite aquifer. These aquifers are naturally bounded by the Hurricane Fault and by drainage divides. On the basis of measurements, estimates, and numerical simulations of reasonable values for all inflow and outflow components, total water moving through the upper Ash Creek drainage basin ground-water system is estimated to be about 14,000 acre-feet per year. Recharge to the upper Ash Creek drainage basin ground-water system is mostly from infiltration of precipitation and seepage from ephemeral and perennial streams. The primary source of discharge is assumed to be evapotranspiration; however, subsurface discharge near Ash Creek Reservoir also may be important. The character of two of the hydrologic boundaries of the upper Ash Creek drainage basin ground-water system is speculative. The eastern boundary provided by the Hurricane Fault is assumed to be a no-flow boundary, and a substantial part of the ground-water discharge from the system is assumed to be subsurface outflow beneath Ash Creek Reservoir along the southern boundary. However, these assumptions might be incorrect because alternative numerical simulations that used different boundary conditions also proved to be feasible. The hydrogeologic character of the aquifers is uncertain because of limited data. Differences in well yield indicate that there is considerable variability in the transmissivity of the basin-fill aquifer. Field data also indicate that the basin-fill aquifer is more transmissive than the underlying alluvial-fan aquifer. Data from the Pine Valley monzonite aquifer indicate that its transmissivity may be highly variable and that it is strongly influenced by the connection of fractures. The Navajo and Kayenta aquifers provide most of the potable water to the municipalities of Washington County. Because of large outcrop exposures, uniform grain size, and large stratigraphic thickness, these formations are able to receive and store large amounts of water. In addition, structural forces have resulted in extensive fracture zones that enhance ground-water recharge and movement within these aquifers. Aquifer testing of the Navajo aquifer indicates that horizontal hydraulic-conductivity values range from 0.2 to 32 feet per day at different locations and may be primarily dependent on the extent of fracturing. Limited data indicate that the Kayenta aquifer generally is less transmissive than the Navajo aquifer. The aquifers are bounded to the south and west by the erosional extent of the formations and to the east by the Hurricane Fault, which completely offsets these formations and is assumed to be a lateral no-flow boundary. Like the Hurricane Fault, the Gunlock Fault is assumed to be a lateral no-flow boundary that divides the Navajo and Kayenta aquifers within the study area into two parts: the main part, between the Hurricane and Gunlock Faults; and the Gunlock part, west of the Gunlock Fault. Generally, the water in the Navajo and Kayenta aquifers contains few dissolved minerals. However, two distinct areas contain water with dissolved-solids concentrations greater than 500 milligrams per liter: a larger area north of the city of St. George and a smaller area a few miles west of the town of Hurricane. Mass-balance calculations indicate that in the higher-dissolved-solids area north of St. George, as much as 2.7 cubic feet per second may be entering the aquifer from underlying formations. For the area west of Hurricane, as much as 1.5 cubic feet per second may be entering the aquifer from underlying formations. On the basis of measurements, estimates, and numerical simulations, total water moving through the Navajo and Kayenta aquifers is estimated to be about 25,000 acre-feet per year for the main part and 5,000 acre-feet per year for the Gunlock part. The primary source of recharge is assumed to be infiltration of precipitation in the main part and seepage from the Santa Clara River in the Gunlock part. The primary source of discharge is assumed to be well discharge for both the main and Gunlock parts of the aquifers. Numerical simulations indicate that faults with major offset, such as the Washington Hollow Fault and an unnamed fault near Anderson Junction, may impede horizontal ground-water flow. Also, increased horizontal hydraulic conductivity along the orientation of predominant surface fracturing may be an important factor in regional ground-water flow. Simulations with increased north-south hydraulic conductivity substantially improved the match to measured water levels in the central area of the model between Snow Canyon and Mill Creek. Numerical simulation of the Gunlock part, using aquifer properties determined for the city of St. George municipal well field, resulted in a reasonable representation of regional water levels and estimated seepage from and to the Santa Clara River. To further quantify the Gunlock part of the Navajo and Kayenta aquifers, a better understanding of ground-water flow at the Gunlock Fault is needed.

Utah↗
USGS2003

Hydrology and simulation of ground-water flow in Kamas Valley, Summit County, Utah

Kamas Valley, Utah, is located about 50 miles east of Salt Lake City and is undergoing residential development. The increasing number of wells and septic systems raised concerns of water managers and prompted this hydrologic study. About 350,000 acre-feet per year of surface water flows through Kamas Valley in the Weber River, Beaver Creek, and Provo River, which originate in the Uinta Mountains east of the study area. The ground-water system in this area consists of water in unconsolidated deposits and consolidated rock; water budgets indicate very little interaction between consolidated rock and unconsolidated deposits. Most recharge to consolidated rock occurs at higher altitudes in the mountains and discharges to streams and springs upgradient of Kamas Valley. About 38,000 acre-feet per year of water flows through the unconsolidated deposits in Kamas Valley. Most recharge is from irrigation and seepage from major streams; most discharge is to Beaver Creek in the middle part of the valley. Long-term water-level fluctuations range from about 3 to 17 feet. Seasonal fluctuations exceed 50 feet. Transmissivity varies over four orders of magnitude in both the unconsolidated deposits and consolidated rock and is typically 1,000 to 10,000 feet squared per day in unconsolidated deposits and 100 feet squared per day in consolidated rock as determined from specific capacity. Water samples collected from wells, streams, and springs had nitrate plus nitrite concentrations (as N) substantially less than 10 mg/L. Total and fecal coliform bacteria were detected in some surface-water samples and probably originate from livestock. Septic systems do not appear to be degrading water quality. A numerical ground-water flow model developed to test the conceptual understanding of the ground-water system adequately simulates water levels and flow in the unconsolidated deposits. Analyses of model fit and sensitivity were used to refine the conceptual and numerical models.

Utah↗
USGS1995

Chemical composition of ground water, hydrologic properties of basin-fill material, and ground-water movement in Salt Lake Valley, Utah

The chemical composition and movement of ground water and hydrologic properties of the basin‑fill material were studied to better under‑ stand the flow system in Salt Lake Valley, Utah. Recharge sources and water‑rock interactions influence the water chemistry in the principal and shallow unconfined aquifers. Chloride concentration in water from some wells has increased from the 1950’s and 1960’s to 1992, possibly because of the infiltration of water that contains dissolved road salt and the movement of ground water with relatively high chloride concentrations from volcanic rocks in the vicinity of these wells. Hydraulic‑conductivity values determined from slug tests done on wells finished in the shallow unconfined aquifer and confining layers ranged from 0.003 to 33.4 feet per day. Transmissivity values determined for the principal aquifer from four multiple‑well aquifer tests ranged from 6,400 to 43,600 feet squared per day. Vertical hydraulic‑conductivity values estimated from these tests are from 0.01 to 1 foot per day. Water from 81 sites was analyzed for the stable‑isotope ratios of oxygen and hydrogen to determine sources of recharge and mixing of water from these sources. Water sampled from the principal aquifer in the southeastern part of the valley is isotopically similar to water in Big and Little Cottonwood Creeks. Ground water sampled from the shallow unconfined aquifer is generally enriched in oxygen‑18 and deuterium relative to other water in the valley, except for water from the Jordan River and its diversions, which are probable recharge sources. Tritium concentrations ranging from about 33 to 59 tritium units in water from the principal aquifer in the southeastern part of the valley are representative of concentrations in water that was recharged in the 1960’s.

Utah↗
USGS1995

Numerical simulation of ground-water flow in basin-fill material in Salt Lake Valley, Utah

A three-dimensional, finite-difference, numerical model was developed to simulate ground-water flow in the basin-fill material in Salt Lake Valley, Utah. The model was calibrated to steady-state and transient-state conditions. The steady-state simulation was developed and calibrated using hydrologic data defining average conditions for 1968. The transient-state simulation was developed and calibrated using hydrologic data from 1969-91. Areally the model grid is 94 rows by 62 columns, with each cell 0.35 mile on a side. Vertically, the aquifer system is divided into seven layers. The model simulates recharge to the basin-fill ground-water flow system from (1) consolidated rock, (2) streams and canals, (3) precipitation on the valley floor, (4) irrigated land, (5) reservoirs and evaporation ponds in the southwestern part of the valley, and (6) underflow at Jordan Narrows. Estimated discharge to wells, canals, and springs is incorporated in the model. During simulation, the model computes (1) ground-water flow to and seepage from the Jordan River and the lower reaches of its principal tributaries, (2) recharge from consolidated rock at the northern end of the Oquirrh Mountains, (3) discharge to drains, and (4) discharge by evapotranspiration. During steady-state calibration, calibration variables were adjusted within probable ranges to minimize differences between model-computed and measured water levels, model-computed and estimated ground-water discharge to the Jordan River, and simulated and measured vertical hydraulic gradients. The transient-state simulation was calibrated to measured water-level changes and estimated annual gains in the Jordan River.

Utah↗
USGS2017

Contaminants of emerging concern in the Great Lakes Basin: A report on sediment, water, and fish tissue chemistry collected in 2010-2012

Despite being detected at low levels in surface waters and sediments across the United States, contaminants of emerging concern (CECs) in the Great Lakes Basin are not well characterized in terms of spatial and temporal occurrence. Additionally, although the detrimental effects of exposure to CECs on fish and wildlife have been documented for many CECs in laboratory studies, we do not adequately understand the implications of the presence of CECs in the environment. Based on limited studies using current environmentally relevant concentrations of chemicals, however, risks to fish and wildlife are evident. As a result, there is an increasing urgency to address data gaps that are vital to resource management decisions. The U.S. Fish and Wildlife Service, in collaboration with the U.S. Geological Survey, is leading a Great Lakes Basin-wide evaluation of CECs (CEC Project) with the objectives to (a) characterize the spatial and temporal distribution of CECs; (b) evaluate risks to fish and wildlife resources; and (c) develop tools to aid resource managers in detecting, averting, or minimizing the ecological consequences to fish and wildlife that are exposed to CECs. This report addresses objective (a) of the CEC Project, summarizing sediment and water chemistry data collected from 2010 to 2012 and fish liver tissue chemistry data collected in 2012; characterizes the sampling locations with respect to potential sources of CECs in the landscape; and provides an initial interpretation of the variation in CEC concentrations relative to the identified sources. Data collected during the first three years of our study, which included 12 sampling locations and analysis of 134 chemicals, indicate that contaminants were more frequently detected in sediment compared to water. Chemicals classified as alkyphenols, flavors/ fragrances, hormones, PAHs, and sterols had higher average detection frequencies in sediment compared to water, while the opposite was observed for pesticides, pharmaceuticals, and plasticizers/flame retardants. The St. Louis River and Maumee River sampling locations had the most CEC detections in water and sediment, relative to other sites, as well as the largest number of maximum detected concentrations across all sites in the Basin. No consistent temporal CEC occurrence patterns were observed at locations sampled multiple times each day. Most appearances and increases in chemical concentrations in sediments occurred at sites immediately downstream from wastewater treatment plants and at sites with predominantly developed land use. The location with the most observed appearances and increases was the St. Louis River. Perfluorinated compounds were commonly detected in fish liver tissues with detections in 100% of both benthic and pelagic species. The occurrence of these chemicals in liver tissue of benthic and pelagic species was generally similar. Abstract

Great Lakes Basin↗
USGS2019

Handbook to the partners in flight population estimates database, version 3.0

This document describes the content of Version 3.0 of the Partners in Flight (PIF) Population Estimates Database, which provides population estimates for breeding USA/Canada landbirds at several geographic scales following the Partners in Flight approach described initially in Rich et al. (2004) and by Rosenberg and Blancher (2005) and most recently refined by Stanton et al. (2019). The Handbook also provides details about how the estimates were derived, information on limitations and caveats, a guide to using the estimates, and future desired directions for improving the estimates. This version of the database is intended as a companion to the Partners in Flight Landbird Conservation Plan: 2016 Revision for Canada and Continental United States (Rosenberg et al. 2016), although estimates for most species included in the database have been updated from those used in the 2016 Plan. Most of the estimates in the database are based on North American Breeding Bird Survey (BBS) data for landbirds from the decade 2006–2015. The information in this 2019 Version of the Handbook, for Version 3.0 of the database, describes all changes that have been made to the database since 2007 (Version 1.0, cf. Blancher et al. 2007)—including the additions documented in the Handbook for Version 2.0 (Blancher et al. 2013)—and therefore serves as a single source document describing the current database. Version 3.0 of the database addresses some of the recommendations suggested by Thogmartin et al. (2006) but does not yet fully address other limitations noted by Thogmartin et al. (2006), Blancher et al. (2007), Thogmartin (2010), Matsuoka et al. (2012), and Twedt (2015). By far, the most substantial change to the database comprises the incorporation of quantitative uncertainty bounds around population estimates for most species (see Stanton et al. 2019 for details). PIF Science anticipates that future versions of the database will occur in stages: first, improving elements of the basic PIF approach (e.g., incorporating more recent BBS data, updating Time of Day Adjustments, and refining Pair Adjustments); next, addressing additional concerns inherent in the PIF approach (e.g., replacing average maximum detection distance bins with research-derived species-specific effective detection radii); and later, perhaps replacing the sample-based PIF approach with a spatially-explicit, model-based (pixel-based) approach that more deliberately incorporates habitat and road biases and the proportion of birds available but not detected by current sampling methodology. This current Version 3.1 of the Handbook updates citations in the Literature Cited and incorporates relatively minor improvements in text clarity over the previous 3.0 version. The content of the Population Estimates Database itself remains the same except for changes to the global and USA/Canada estimates for Northern Bobwhite and Black Vulture.

Partners in Flight Technical Publication↗
USGS2023

Obtaining and applying public data for training students in technical statistical writing: Case studies with data from U.S. Geological Survey and general ecological literature

Effective undergraduate statistical education requires training using real-world data. Textbook datasets seldom match the complexities and messiness of real-world data and finding these datasets can be challenging for educators. Consulting and industrial datasets often have nondisclosure agreements. Academic datasets often require subject area expertise beyond those of a general education or lack connections to real-world applications. Many governments, including the United States, now require the release of data from projects they directly complete or fund though grants and contracts. We show how statistical educators may find datasets and incorporate them into courses. Specifically, we use two examples from the U.S. Geological Survey (USGS) and one example from the ecology literature. We demonstrate the use of these datasets in an upper-level analysis of variance (ANOVA) class. In addition to describing how we found the datasets, we describe how to include them into course work and the course’s student assessments. We have used these datasets over multiple semesters and included student feedback from these courses. Although our examples focus on an ANOVA class, the general methods for finding data shared here could be used for statistical classes ranging from high school to graduate education. Supplementary materials for this article are available online.

Journal of Statistics and Data Science Education↗
USGS1987

Selected literature on water-resources investigations in New Jersey by the U.S. Geological Survey, through 1986

Because of the importance and complexity of the water resources of New Jersey today, there is a need for a current bibliography to serve as a basis for future water resources studies. This report lists about 400 book reports, map reports, and articles that deal with the water resources of New Jersey published through 1986. The publications are grouped under three major headings: (1) publications of the U.S. Geological Survey, (2) publications of State agencies prepared by or in cooperation with the U.S. Geological Survey, and (3) other publications, such as technical journals prepared by or co-authored by U.S. Geological Survey personnel. Most of the publications are available for inspection at the West Trenton office of the U.S. Geologic Survey and at large public and university libraries. Ordering information is given for those publications that are for sale. (USGS)

Open-File Report↗
USGS2008

Linking environmental risk assessment and communication: An experiment in co-evolving scientific and social knowledge

Dissemination of information to decision-makers and enhanced methods of public participation are often put forward as antidotes to a perceived disconnect between risk assessment and risk communication in the public domain. However, mechanisms that support both the provision of routine, timely and relevant technical knowledge to the public and meaningful opportunities for public participation in the evaluation and management of risk are few. We argue for the need to re-conceptualise the institutional context in which risk research and communication occur as one in which scientific knowledge and public understanding are co-evolutionary instead of independent or sequential. Here, we report on an experiment to promote coevolution of environmental risk assessment and risk communication through the instrumental use of a web-based platform that dynamically links expert and public discourses through common information sources, linked scenario evaluations, and opportunities for iterative dialogue. On the basis of technical feasibility, research value and public communication capacity, we conclude that there is potential for further refinement of the methodologies presented here. Copyright ?? 2008 Inderscience Enterprises Ltd.

International Journal of Global Environmental Issu↗
USGS2022

Planetary geologic mapping protocol—2022

The Planetary Geologic Mapping Protocol covers the idealized process of compiling a NASA-funded map product of a non-terrestrial solid surface planetary body for U.S. Geological Survey (USGS) publication and summarizes technical specifications of the Mapping Process for authors and reviewers. Directed by community and programmatic recommendations, the USGS Planetary Geologic Map Coordination Group assembled the content herein to aid the timely production of USGS map products. This document can be also used as a reference document by those researchers who are completing geologic maps that will be published outside the USGS.

Techniques and Methods↗
USGS2023

The 2023 US 50-State National Seismic Hazard Model: Overview and implications

The US National Seismic Hazard Model (NSHM) was updated in 2023 for all 50 states using new science on seismicity, fault ruptures, ground motions, and probabilistic techniques to produce a standard of practice for public policy and other engineering applications (defined for return periods greater than ∼475 or less than ∼10,000 years). Changes in 2023 time-independent seismic hazard (both increases and decreases compared to previous NSHMs) are substantial because the new model considers more data and updated earthquake rupture forecasts and ground-motion components. In developing the 2023 model, we tried to apply best available or applicable science based on advice of co-authors, more than 50 reviewers, and hundreds of hazard scientists and end-users, who attended public workshops and provided technical inputs. The hazard assessment incorporates new catalogs, declustering algorithms, gridded seismicity models, magnitude-scaling equations, fault-based structural and deformation models, multi-fault earthquake rupture forecast models, semi-empirical and simulation-based ground-motion models, and site amplification models conditioned on shear-wave velocities of the upper 30 m of soil and deeper sedimentary basin structures. Seismic hazard calculations yield hazard curves at hundreds of thousands of sites, ground-motion maps, uniform-hazard response spectra, and disaggregations developed for pseudo-spectral accelerations at 21 oscillator periods and two peak parameters, Modified Mercalli Intensity, and 8 site classes required by building codes and other public policy applications. Tests show the new model is consistent with past ShakeMap intensity observations. Sensitivity and uncertainty assessments ensure resulting ground motions are compatible with known hazard information and highlight the range and causes of variability in ground motions. We produce several impact products including building seismic design criteria, intensity maps, planning scenarios, and engineering risk assessments showing the potential physical and social impacts. These applications provide a basis for assessing, planning, and mitigating the effects of future earthquakes.

Earthquake Spectra↗
USGS2024

The U.S. Geological Survey Volcano Science Center’s response plan for significant volcanic events

This publication describes the U.S. Geological Survey Volcano Science Center (VSC) Response Plan for Significant Volcanic Events (hereinafter referred to as “the plan”) that has been developed for U.S volcano observatories over the past several years in consultation with the lead scientist, or Scientist-in-Charge (SIC), of each of the five U.S. Geological Survey (USGS) volcano observatories. The goal of the plan is to define a standardized management system that ensures the VSC can achieve the following during a volcanic crisis: maintain situational awareness and issue timely warnings and hazard assessments, fulfill internal and external agency requests for information as well as requests from the public, sustain financial and technical support, and gather critical scientific data. The plan addresses situations in which the scale of a response at least temporarily eclipses the response capabilities of a single observatory. The plan features two integrated response structures for managing and carrying out operations within the VSC during a crisis: the Observatory Volcanic Event Response Team (OVERT) and the Center Volcanic Event Response Team (CVERT). The design of these structures reflects lessons learned from past volcanic responses and is influenced by the Incident Command System used by the U.S. Federal Government for managing emergency responses. The plan clarifies expectations regarding the flow of information during a response, summarizes required tasks of the responding observatory and VSC to ensure a successful response, defines response-team roles and responsibilities, and describes the internal communication practices critical for an effective and coordinated response.

Circular↗