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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 811 records · Page 45Linked to original sources
USGS2000

Rapid distribution of earthquake information for everybody

No matter who you are, seismologist or regular person on the street, when you feel the Earth move you want to know what's going on. Was it an earthquake? Where was the earthquake? How big was it? As a grad student, many moons ago, when the Earth moved, the Electronic Seismologist (ES) was known to immediately turn on the “AM/FM-Automatic-Earthquake-Locator.” Before the seismograms could be pulled off the photographic drums, developed, and read and an “official” hypocenter determined (using a large map and a piece of string to swing arcs), the radio would usually have reported a location. Individuals feeling the earthquake would have called radio and TV stations (not to mention the police, newspapers, and sometimes the seismograph station), reported feeling something, and described what it was like. Reporters taking these calls got pretty good at estimating roughly where the event was, and they sometimes came up with a fairly good estimate of the magnitude. This seat-of-the-pants radio-seismology is fast becoming a lost art. Reporters now race to their computers and point their Web browsers at the nearest seismic network where they can count on finding, within minutes, an automatic but “official” location and magnitude for the earthquake.

Seismological Research Letters↗
USGS2024

New 10Be-26Al isochron burial dating informs the Pliocene and Pleistocene evolution of the lower Colorado River, southwestern United States

Four new 10 Be- 26 Al isochron burial ages ranging from 4.4 to 2 Ma on ancestral Colorado River deposits in the lower Colorado River corridor (LCRC) help constrain the river’s evolution during the Pliocene and early Pleistocene. They help fill a gap between previous work that focused on older and younger deposits: Older dated deposits include the 5 Ma Bouse Formation, which records the integration of the Colorado River through a series of preexisting basins to the Gulf of California and the ca. 4.5 - 3.5 Ma Bullhead Alluvium, a 200 to 300 m thick aggregational package that immediately followed integration. The much younger, 100 - 70 ka, Chemehuevi Formation is another major aggradation package mapped throughout the LCRC. The new burial ages on the facies of Santa Fe Railway (4.37 ± 0.71 Ma), boulder conglomerate of Bat Cave Wash (2.12 ± 0.26 and 2.05 ± 0.31 Ma), and the Palo Verde alluvium (3.03 ± 0.26 Ma) partially fill in a 3.5 M.y. gap between the deposition of the Bullhead Alluvium and the Chemeheuvi Formation and document the timescales over which the Colorado River was able to remove the Bullhead aggradational package and initiate newer and smaller aggradational pulses.

Arizona, California, Nevada↗
USGS2019

BbsAssistant: An R package for downloading and handling data and information from the North American Breeding Bird Survey

This R package contains functions for downloading and munging data from the U.S. Geological Surveys North American Breeding Bird Survey (BBS) via file transfer protocol (FTP) (Pardieck, Ziolkowski Jr, Lutmerding, & Hudson, 2018; J. R. Sauer et al., 2017). This package was created to allow the user to bulk-download the BBS point count and related (e.g., route-level conditions) via FTP, and to quickly subset the data by taxonomic classifications and/or geographical locations. This package also maintains data containing the trend and annual indices from the most recent (1996-2017) hierarchical population analyses (J. Sauer et al., 2017).

Journal of Open Source Software↗
USGS1985

Regional setting and new information on some critical geologic features of the West Shasta district, California

The West Shasta massive sulfide district is in the easternmost of a series of accreted island-arc and oceanic crust terranes that comprise the Klamath Mountains. A sequence of submarine volcanic rocks of predominantly Early Devonian age is the principal component of the island-arc terrane in which the sulfide deposits are hosted. The Copley Greenstone, consisting mainly of andesitic and basaltic pillow lavas and breccias totaling at least 1,800 m in thickness, is the oldest rock unit in the sequence. It is overlain and also intruded by dikes of the Balaklala Rhyolite. Northeast of the West Shasta district, greenstone also overlies the Balaklala Rhyolite, suggesting that a major greenstone unit may overlie potentially mineralized rhyolite east of the district. However, recent studies have shown that the complex relations in that area can be explained by folding.The Balaklala sequence consists of silicic flows, breccias, and tuffs having a maximum thickness somewhat in excess of 1,000 m. The Balaklala has been divided by Kinkel et al. (1956) into three units: a lower nonporphyritic to slightly porphyritic unit containing large amounts of breccia and tuff; a middle unit characterized by rhyolite containing quartz phenocrysts 1 to 4 mm in diameter but also containing a complex assortment of tuff, breccia, and pyritic massive sulfide bodies in its upper part; and an upper unit typically containing dark quartz phenocrysts in excess of 4 mm in diameter. Much of the lower part of the upper unit is pyroclastic material, whereas most of the upper part of the unit appears to be a massive volcanic-flow rock. At least half a dozen eruptive centers for the Balaklala Rhyolite are identified, three of them within an area measuring 17 X 3 km that constitutes the limits of the former mining district.The youngest unit in the arc sequence is the Kennett Formation consisting of black shale and chert containing radiolarians, which indicate fairly deep-water deposition in its lower part, and limestone containing a shallow water fauna of probable Middle Devonian age in the upper part. A 400-m.y.-old trondhjemite stock, named the Mule Mountain stock, intrudes the Copley Greenstone and Balaklala Rhyolite and is considered to be essentially coeval with these volcanic units.The pyritic massive sulfide deposits occur in clusters of individual bodies owing in large part to disruption by postmineral faults. The deposits are stratigraphically confined to the upper part of the subhorizontal middle unit of the Balaklala, and their horizontal distribution is here interpreted to have been controlled by an extensional tectonic regime that prevailed during Early Devonian time. The major geologic evidence for such a regime is the marked preferred elongations exhibited by the distribution of the afore-mentioned eruptive centers, the eight or nine massive sulfide clusters in the district, and the geometrically similar distribution of the clusters in relation to each other. The preferred directions of elongation in both the detailed and broader senses may be generalized to N 20 degrees to 25 degrees E, N 37 degrees E, N 60 degrees to 80 degrees E, and N 40 degrees to 60 degrees W. The three northeast trends dominate throughout the district, whereas the northwest trend is evident mainly in the northern part and is more speculative. The major deposit clusters fall at intersections of the major trends, some of which may have been grabens. Trend intersections having no known deposits may be good exploration targets in localities where the stratigraphically favorable middle unit of the Balaklala is still present.

Economic Geology↗
USGS2020

Further information on the avifauna of St. Matthew and Hall Islands, Bering Sea, Alaska

In June and July 2018 and July 2019 we surveyed birds on St. Matthew and Hall islands, isolated in the central Bering Sea. Our surveys were focused on the McKay’s Bunting (Plectrophenax hyperboreus), Rock Sandpiper (Calidris ptilocnemis ptilocnemis), and Pelagic Cormorant (Phalacrocorax pelagicus) but encompassed all birds and yielded 13 species and four subspecies new to the islands’ avifaunal list, and new details and documentation of breeding for eight species. Especially notable discoveries include a mixed pair of Bewick’s (Cygnus columbianus bewickii) and Whistling (C. c. columbianus) Swans, a mixed pair of the Glaucous-winged (Larus glaucescens) and an Asian subspecies of the Herring Gull (L. argentatus vegae), and discovery of a colony of ~100 pairs of the Red-legged Kittiwake (Rissa brevirostris). Also, contrary to many previous expeditions, we found the Gray-crowned Rosy-Finch (Leucosticte tephrocotis umbrina) to be common and conclude that it may be resident.

Alaska↗
USGS2016

Contrasting nitrogen fate in watersheds using agricultural and water quality information

Surplus nitrogen (N) estimates, principal component analysis (PCA), and end-member mixing analysis (EMMA) were used in a multisite comparison contrasting the fate of N in diverse agricultural watersheds. We applied PCA-EMMA in 10 watersheds located in Indiana, Iowa, Maryland, Nebraska, Mississippi, and Washington ranging in size from 5 to 1254 km 2 with four nested watersheds. Watershed Surplus N was determined by subtracting estimates of crop uptake and volatilization from estimates of N input from atmospheric deposition, plant fixation, fertilizer, and manure for the period from 1987 to 2004. Watershed average Surplus N ranged from 11 to 52 kg N ha −1 and from 9 to 32% of N input. Solute concentrations in streams, overland runoff, tile drainage, groundwater (GW), streambeds, and the unsaturated zone were used in the PCA-EMMA procedure to identify independent components contributing to observed stream concentration variability and the end-members contributing to streamflow and NO 3 load. End-members included dilute runoff, agricultural runoff, benthic-processing, tile drainage, and oxic and anoxic GW. Surplus N was larger in watersheds with more permeable soils (Washington, Nebraska, and Maryland) that allowed greater infiltration, and oxic GW was the primary source of NO 3 load. Subsurface transport of NO 3 in these watersheds resulted in some removal of Surplus N by denitrification. In less permeable watersheds (Iowa, Indiana, and Mississippi), NO 3 was rapidly transported to the stream by tile drainage and runoff with little removal. Evidence of streambed removal of NO 3 by benthic diatoms was observed in the larger watersheds.

Indiana, Iowa, Maryland, Nebraska, Mississippi, Wa↗
USGS2025

Potential for continental scientific drilling to inform fault mechanics and earthquake science

Our understanding of fault mechanics and earthquake processes remains limited, largely due to minimal direct observations near active faults at seismogenic depths. This lack of data restricts our ability to accurately assess and mitigate both natural and human-induced seismic hazards. However, recent advancements in drilling capabilities and downhole sensing technologies offer an opportunity: the ability to observe the physical conditions within a volume near active fault zones. In this contribution, we highlight how scientific drilling can provide access to the near-fault environment, enabling measurements of the stress, temperature, fluid pressure, and rock properties at depths where ruptures initiate, propagate, and arrest. These observations are essential to refine models of earthquake nucleation and dynamic rupture, bridging gaps between laboratory experiments, numerical simulations, and surface observations. These insights can advance fundamental understanding in earthquake science but also support the development of more effective seismic hazard assessments and risk mitigation strategies.

Seismica↗
USGS2025

Beyond the mangroves: A global synthesis of tidal forested wetland types, drivers and future information opportunities

There is increasing awareness of the global diversity of tidal forested wetlands (TFWs) and their significance in the provision of ecosystem services. These ecosystems, including mangrove forests, tidal freshwater forested wetlands, supratidal forests and transitional forests together span multiple climatic zones, geomorphic settings, and inundation and salinity regimes. We utilise case studies across five continents to demonstrate the state of knowledge among TFWs. Intertidal mangroves are the best-defined of the TFWs thanks to decades of research on their geomorphology, hydrology and ecology across their broad distribution. Non-mangrove forest settings, however, demonstrate more diverse hydrological, biochemical and vegetation conditions. In many cases, non-mangrove forests are situated at upper intertidal or supratidal elevations, where surface waters and groundwater are subject to interactions between tides freshwater inputs. Salinity datasets show variations ranging from tidal freshwater forested wetlands and ‘low-salinity mangroves’ to mesohaline or marine salinities, often with high temporal variability. While the floristic composition of non-mangrove forests vary among biogeographic regions, locally dominant TFW species are commonly distributed beyond the tidal niche into non-tidal wetland and upland forests. This presents challenges for traditional remote sensing approaches to ecosystem mapping, which are mostly lacking for non-mangrove forests. Geomorphic approaches and developments in machine learning offer opportunities to address this.

Preprint↗
USGS1978

National Cartographic Information Center Newsletter No. 8

In this issue we cover several interesting topics, including a report on the NCIC/Special Libraries Association meeting in Denver, the launching of a third Landsat satellite with a new thermal band, and the formation of a new California map society.

Newsletter↗
USGS2011

Informal trail monitoring protocols: Denali National Park and Preserve

The National Park Service (NPS) accommodates nearly 300 million visitors per year, visitation that presents managers with substantial challenges at some 394 park units across some 83.6 million acres of protected lands. An increasing number of visitors inevitably contribute negative effects to fragile natural and cultural resources. Such visitation - related resource impacts can degrade natural conditions and processes and the quality of recreation experiences. According to the NPS Management Policies: ―The fundamental purpose of the national park system , established by the Organic Act and reaffirmed by the General Authorities Act, as amended, begins with a mandate to conserve park resources and values...The fundamental purpose of all parks also includes providing for the enjoyment of park resources and values by the people of the United States.‖ (NPS 2006 b , Section 1.4.3). However, what might appear to be dual mandates, visitation and resource protection, are clarified to reveal the primacy of resource protection. The Management Policies acknowledge that so me resource degradation is an inevitable consequence of visitation, but directs managers to ―ensure that any adverse impacts are the minimum necessary, unavoidable, cannot be further mitigated, and do not constitute impairment or derogation of park resources and values‖ (NPS 2006 b ).

Alaska↗
USGS1986

Geologic and grade-tonnage information on Tertiary epithermal precious- and base-metal vein districts associated with volcanic rocks

Data on grades, tonnages, and geology of selected Tertiary epithermal precious- and base-metal vein districts associated with volcanic rocks were tabulated for ease of examination and comparison of characteristics between districts. There are 215 districts listed, with a cumulative tonnage of 709 million metric tons and average grades of 4.7 g/t Au, 224 g/t Ag, 0.16 percent Cu, 0.55 percent Pb, and 0.83 percent Zn, representing about 60 percent of world districts.

Bulletin↗