SEARCH · USGS Science

Results for “Near Surface Geophysics”

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

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources

USGS2010

Lunar basin formation and highland stratigraphy

Multiring impact basins, formed after solidification of the lunar crust, account for most or all premare regional deposits and structures expressed in the lunar landscape and for major topographic and gravity variations. A fresh basin has two or more concentric mountain rings, a lineated ejecta blanket, and secondary impact craters. Crackled material on the floor may be impact melt. The ejecta blanket was emplaced at least partly as a ground‐hugging flow and was probably hot. A suggested model of basin formation is that the center lifts up and the rings form by inward collapse during evisceration. The resulting basin is shallow and has a central uplift of the mantle. This results in a central gravity high and a ring low. Later flooding by mare basalt has since modified most near side basins. Highland deposits of plains, furrowed and pitted terrain, and various hills, domes, and craters that were interpreted before the Apollo missions as being volcanic can now be interpreted as being basin related. A province map of the whole moon shows that the relatively young Orientale and Imbrium basins imprinted and rejuvenated much of the moon's surface; older basins must have also. The most primitive cratered surface remaining is mostly on the far side, distant from Imbrium and Orientale and other large relatively young basins. All five lunar landings in the highlands sampled stratigraphic units probably related to basins. Several nearly obliterated basins have been discovered recently, including a deep one on the far side that is as wide as the moon's radius. The presence of these ancient basins suggests that the surface is effectively saturated by basins and that many others were completely destroyed by later impacts. Basin impacts may have churned the lunar crust to large depths.

Reviews of Geophysics and Space Physics↗

USGS2010

Compilation of Water-Resources Data and Hydrogeologic Setting for the Allison Woods Research Station in Iredell County, North Carolina, 2005-2008

Water-resources data were collected to describe the hydrologic conditions at the Allison Woods research station near Statesville, North Carolina, in the Piedmont Physiographic Province of North Carolina. Data collected by the U.S. Geological Survey and the North Carolina Department of Environment and Natural Resources, Division of Water Quality, from April 2005 through September 2008 are presented in this report. Data presented include well-construction characteristics and periodic groundwater-level measurements for 29 wells, borehole geophysical logs for 8 wells, hourly groundwater-level measurements for 5 wells, continuous water-quality measurements for 3 wells, periodic water-quality samples for 12 wells and 1 surface-water station, slug-test results for 11 wells, and shallow groundwater-flow maps. In addition, the geology and hydrogeology at the site are summarized.

North Carolina↗

USGS1992

Hydrology and digital simulation of the regional aquifer system, eastern Snake River Plain, Idaho

The occurrence and movement of water in the regional aquifer system that underlies the eastern Snake River Plain, Idaho, de- pend on the transmissivity and storage capacity of rocks that compose the geologic framework and on the distribution and amount of recharge and discharge of water within that frame- work. On a regional scale, most water moves horizontally through interflow zones in Quaternary basalt of the Snake River Group. In recharge and discharge areas, water also moves vertically along joints and interfingering edges of basalt flows. Aquifer thickness is largely unknown, but geophysical studies suggest that locally the Quaternary basalt may exceed several thousand feet. Along the margins of the plain, sand and gravel several hundred feet thick transmit large volumes of water. Regional ground-water movement is generally from northeast to southwest, from areas of recharge to areas of discharge. Re- charge is from seepage of surface water used for irrigation, stream and canal losses, underflow from tributary drainage ba- sins, and infiltration of precipitation. Aquifer discharge is largely spring flow to the Snake River and water pumped for irrigation. Major springs are near American Falls Reservoir and along the Snake River from Milner Dam to King Hill. Regional ground-water flow was simulated with numerical models. Initially, a two-dimensional steady-state model that in- cluded a nonlinear, least-squares regression technique was used to estimate aquifer properties. Later, a three-dimensional steady- state and transient model was used to replace the two-dimen- sional model. Three-dimensional model results indicated that average total transmissivity ranged from about 0.05 to 120 feet squared per second and vertical leakance ranged from about 3 x 10 -10 to 5 x 10 -6 feet per second per foot of aquifer thickness. The three-dimensional transient model was used to compare measured and estimated long-term changes in ground-water dis- charge and water levels with simulated values. Initial head con- ditions used in transient simulations were derived from a steady-state solution of estimated preirrigation hydrologic condi- tions. Transient simulations were 5-year stress periods beginning in 1891 and ending in 1980. Recharge for each stress period from 1926 to 1980 was estimated from surface-water irrigation, pre- cipitation, and streamflow records. Recharge for stress periods from 1891 to 1925 was based on the average value for stress peri- ods from 1926 to 1980 and was indexed to estimated irrigated acreages. Average annual tributary drainage-basin underflow for stress periods from 1891 to 1910 was calculated by using basin- yield equations. Underflow for stress periods from 1911 to 1980 was varied by use of streamflow records. Transient simulations reasonably approximated measured changes in aquifer head and ground-water discharge that re- sulted from use of surface water for irrigation. Irrigation with surface water peaked in about 1950; subsequent increases in irri- gation have been supplied largely by ground water. The three- dimensional model simulated water-level declines and reduced ground-water discharge caused in part by increases in ground- water pumping. The transient model was used to simulate aquifer changes from 1981 to 2010 in response to three hypothetical development alternatives: (1) Continuation of 1980 hydrologic conditions, (2) increased pumpage, and (3) increased recharge. Simulation of continued 1980 hydrologic conditions for 30 years indicated that head declines of 2 to 8 feet might be expected in the central part of the plain. The magnitude of simulated head declines was con- sistent with head declines measured during the 1980 water year. Larger declines were calculated along model boundaries, but these changes may have resulted from underestimation of tribu- tary drainage-basin underflow and inadequate aquifer definition. Simulation of increased ground-water pumpage (an additional 2,400 cubic feet per second) for 30 years indicated head declines of 10 to 50 feet in the central part of the plain. These relatively large head declines were accompanied by increased simulated river leakage of 50 percent and decreased spring discharge of 20 percent. The effect of increased recharge (800 cubic feet per sec- ond) for 30 years was a rise in simulated heads of 0 to 5 feet in the central part of the plain.

Idaho;Oregon↗

USGS2003

Sources of global warming of the upper ocean on decadal period scales

Recent studies find global climate variability in the upper ocean and lower atmosphere during the twentieth century dominated by quasi-biennial, interannual, quasi-decadal and interdecadal signals. The quasi-decadal signal in upper ocean temperature undergoes global warming/cooling of ???0.1??C, similar to that occuring with the interannual signal (i.e., El Nin??o-Southern Oscillation), both signals dominated by global warming/cooling in the tropics. From the National Centers for Environmental Prediction troposphere reanalysis and Scripps Institution of Oceanography upper ocean temperature reanalysis we examine the quasi-decadal global tropical diabetic heat storage (DHS) budget from 1975 to 2000. We find the anomalous DHS warming tendency of 0.3-0.9 W m-2 driven principally by a downward global tropical latent-plus-sensible heat flux anomaly into the ocean, overwhelming the tendency by weaker upward shortwave-minus-longwave heat flux anomaly to drive an anomalous DHS cooling tendency. During the peak quasi-decadal warming the estimated dissipation of DHS anomaly of 0.2-0.5 W m-2 into the deep ocean and a similar loss to the overlying atmosphere through air-sea heat flux anomaly are balanced by a decrease in the net poleward Ekman heat advection out of the tropics of 0.4-0.7 W m-2. This scenario is nearly the opposite of that accounting for global tropical warming during the El Nin??o. These diagnostics confirm that even though the global quasi-decadal signal is phase-locked to the 11-year signal in the Sun's surface radiative forcing of ???0.1 W m-2, the anomalous global tropical DHS tendency cannot be driven by it directly.

Journal of Geophysical Research C: Oceans↗

USGS1996

Crustal velocity field near the big bend of California's San Andreas fault

We use geodetic data spanning the 1920–1992 interval to estimate the horizontal velocity field near the big bend segment of California's San Andreas fault (SAF). More specifically, we estimate a horizontal velocity vector for each node of a two-dimensional grid that has a 15-min-by-15-min mesh and that extends between latitudes 34.0°N and 36.0°N and longitudes 117.5°W and 120.5°W. For this estimation process, we apply bilinear interpolation to transfer crustal deformation information from geodetic sites to the grid nodes. The data include over a half century of triangulation measurements, over two decades of repeated electronic distance measurements, a decade of repeated very long baseline interferometry measurements, and several years of Global Positioning System measurements. Magnitudes for our estimated velocity vectors have formal standard errors ranging from 0.7 to 6.8 mm/yr. Our derived velocity field shows that (1) relative motion associated with the SAF exceeds 30 mm/yr and is distributed on the Earth's surface across a band (>100 km wide) that is roughly centered on this fault; (2) when velocities are expressed relative to a fixed North America plate, the motion within our primary study region has a mean orientation of N44°W ± 2° and the surface trace of the SAF is congruent in shape to nearby contours of constant speed yet this trace is oriented between 5° and 10° counterclockwise relative to these contours; and (3) large strain rates (shear rates > 150 nrad/yr and/or areal dilatation rates < −150 nstr/yr) exist near the Garlock fault, near the White Wolf fault, and in the Ventura basin.

Journal of Geophysical Research B: Solid Earth↗

USGS2015

A Green's function approach for assessing the thermal disturbance caused by drilling deep boreholes in rock or ice

A knowledge of subsurface temperatures in sedimentary basins, fault zones, volcanic environments and polar ice sheets is of interest for a wide variety of geophysical applications. However, the process of drilling deep boreholes in these environments to provide access for temperature and other measurements invariably disturbs the temperature field around a newly created borehole. Although this disturbance dissipates over time, most temperature measurements are made while the temperature field is still disturbed. Thus, the measurements must be ‘corrected’ for the drilling-disturbance effect if the undisturbed temperature field is to be determined. This paper provides compact analytical solutions for the thermal drilling disturbance based on 1-D (radial) and 2-D (radial and depth) Green's functions (GFs) in cylindrical coordinates. Solutions are developed for three types of boundary conditions (BCs) at the borehole wall: (1) prescribed temperature, (2) prescribed heat flux and (3) a prescribed convective condition. The BC at the borehole wall is allowed to vary both with depth and time. Inclusion of the depth dimension in the 2-D solution allows vertical heat-transfer effects to be quantified in situations where they are potentially important, that is, near the earth's surface, at the bottom of a well and when considering finite-drilling rates. The 2-D solution also includes a radial- and time-dependent BC at the earth's surface to assess the impact of drilling-related infrastructure (drilling pads, mud pits, permanent shelters) on the subsurface temperature field. Latent-heat effects due to the melting and subsequent refreezing of interstitial ice while drilling a borehole through ice-rich permafrost can be included in the GF solution as a moving-plane heat source (or sink) located at the solid–liquid interface. Synthetic examples are provided illustrating the 1-D and 2-D GF solutions. The flexibility of the approach allows the investigation of thermal drilling effects in rock or ice for a wide variety of drilling technologies. Numerical values for the required radial GFs G R are available through the Advanced Cooperative Arctic Data and Information Service at doi:10.5065/D64F1NS6.

Geophysical Journal International↗

USGS2010

Estimating the timing and location of shallow rainfall-induced landslides using a model for transient, unsaturated infiltration

Shallow rainfall-induced landslides commonly occur under conditions of transient infiltration into initially unsaturated soils. In an effort to predict the timing and location of such landslides, we developed a model of the infiltration process using a two-layer system that consists of an unsaturated zone above a saturated zone and implemented this model in a geographic information system (GIS) framework. The model links analytical solutions for transient, unsaturated, vertical infiltration above the water table to pressure-diffusion solutions for pressure changes below the water table. The solutions are coupled through a transient water table that rises as water accumulates at the base of the unsaturated zone. This scheme, though limited to simplified soil-water characteristics and moist initial conditions, greatly improves computational efficiency over numerical models in spatially distributed modeling applications. Pore pressures computed by these coupled models are subsequently used in one-dimensional slope-stability computations to estimate the timing and locations of slope failures. Applied over a digital landscape near Seattle, Washington, for an hourly rainfall history known to trigger shallow landslides, the model computes a factor of safety for each grid cell at any time during a rainstorm. The unsaturated layer attenuates and delays the rainfall-induced pore-pressure response of the model at depth, consistent with observations at an instrumented hillside near Edmonds, Washington. This attenuation results in realistic estimates of timing for the onset of slope instability (7 h earlier than observed landslides, on average). By considering the spatial distribution of physical properties, the model predicts the primary source areas of landslides.

Journal of Geophysical Research F: Earth Surface↗

USGS2022

Chemical geodynamics insights from a machine learning approach

The radiogenic isotope heterogeneity of oceanic basalts is often assessed using 2D isotope ratio diagrams. But because the underlying data are at least six dimensional ( 87 Sr/ 86 Sr, 143 Nd/ 144 Nd, 176 Hf/ 177 Hf, and 208,207,206 Pb/ 204 Pb), it is important to examine isotopic affinities in multi-dimensional data space. Here, we apply t-distributed stochastic neighbor embedding (t-SNE), a multi-variate statistical data analysis technique, to a recent compilation of radiogenic isotope data of mid ocean ridge (MORB) and ocean island basalts (OIB). The t-SNE results show that the apparent overlap of MORB-OIB data trends in 2-3D isotope ratios diagrams does not exist in multi-dimensional isotope data space, revealing that there is no discrete “component” that is common to most MORB-OIB mantle sources on a global scale. Rather, MORB-OIB sample stochastically distributed small-scale isotopic heterogeneities. Yet, oceanic basalts with the same isotopic affinity, as identified by t-SNE, delineate several globally distributed regional domains. In the regional geodynamic context, the isotopic affinity of MORB and OIB is caused by capturing of actively upwelling mantle by adjacent ridges, and thus melting of mantle with similar origin in on, near, and off-ridge settings. Moreover, within a given isotopic domain, subsidiary upwellings rising from a common deep mantle root often feed OIB volcanism over large surface areas. Overall, the t-SNE results define a fundamentally new basis for relating isotopic variations in oceanic basalts to mantle geodynamics, and may launch a 21st century era of “chemical geodynamics.”

Geochemistry, Geophysics, Geosystems↗

USGS2012

The use of MAGSAT data to determine secular variation

A combined spatial and secular variation model of the geomagnetic field, labeled M061581, is derived from a selection of Magsat data. Secular variation (SV) data computed from linear fits to midnight hourly values from 19 magnetic observatories were also included in the analysis but were seen to have little effect on the model. The SV patterns from this new model are compared with those from the 1980 IGRF and with those for 1970 computed by the DGRF and with the 1960 patterns computed using the GSFC(12/66) model. Most of the features of the M061581 are identical in location and level with those of the 1980 IGRF. Together they confirm that the reversals in sign of field change seen over Asia and North America between 1965 and 1975 are reverting to the pre-1965 states. The M061581 model gives −32 nT/yr for the dipole decay rate, larger than the 70% increase already reported since 1965. This abnormally high value is interpreted as being a defect of the model because it appears to result from a much larger (−100 nT/yr) drop in field over the polar regions not indicated by the 1980 IGRF. This north polar decrease is shown to be of external origin as the result of a combination of the seasonal effect of the north polar ionospheric (counterclockwise) afternoon Sq p cell increasing in intensity from the beginning (November 1979) to the end (June 1980) of the Magsat data collection period, coupled with an enhancement of its effect as the orbit lowered from the 350– 550 km initial altitudes to near 200 km just prior to burnup. This experiment indicates that secular variation can be obtained from satellite data for intervals of less than a full year if corrections can be made for seasonal effects and that ‘annual snapshots’ of the field by a satellite would allow easy and accurate models of secular change without the use of any surface data.

Journal of Geophysical Research Solid Earth↗

USGS2021

Unsaturated flow processes and the onset of seasonal deformation in slow-moving landslides

Predicting rainfall-induced landslide motion is challenging because shallow groundwater flow is extremely sensitive to the preexisting moisture content in the ground. Here, we use groundwater hydrology theory and numerical modeling combined with five years of field monitoring to illustrate how unsaturated groundwater flow processes modulate the seasonal pore water pressure rise and therefore the onset of motion for slow-moving landslides. The onset of landslide motion at Oak Ridge earthflow in California’s Diablo Range occurs after an abrupt water table rise to near the landslide surface 52–129 days after seasonal rainfall commences. Model results and theory suggest that this abrupt rise occurs from the advection of a nearly saturated wetting front, which marks the leading edge of the integrated downward flux of seasonal rainfall, to the water table. Prior to this abrupt rise, we observe little measured pore water pressure response within the landslide due to rainfall. However, once the wetting front reaches the water table, we observe nearly instantaneous pore water pressure transmission within the landslide body that is accompanied by landslide acceleration. We cast the timescale to reach a critical pore water pressure threshold using a simple mass balance model that considers variable moisture storage with depth and explains the onset of seasonal landslide motion with a rainfall intensity-duration threshold. Our model shows that the seasonal response time of slow-moving landslides is controlled by the dry season vadose zone depth rather than the total landslide thickness.

California↗

USGS2009

On near-source earthquake triggering

[1] When one earthquake triggers others nearby, what connects them? Two processes are observed: static stress change from fault offset and dynamic stress changes from passing seismic waves. In the near-source region ( r ≤ 50 km for M ∼ 5 sources) both processes may be operating, and since both mechanisms are expected to raise earthquake rates, it is difficult to isolate them. We thus compare explosions with earthquakes because only earthquakes cause significant static stress changes. We find that large explosions at the Nevada Test Site do not trigger earthquakes at rates comparable to similar magnitude earthquakes. Surface waves are associated with regional and long-range dynamic triggering, but we note that surface waves with low enough frequency to penetrate to depths where most aftershocks of the 1992 M = 5.7 Little Skull Mountain main shock occurred (∼12 km) would not have developed significant amplitude within a 50-km radius. We therefore focus on the best candidate phases to cause local dynamic triggering, direct waves that pass through observed near-source aftershock clusters. We examine these phases, which arrived at the nearest (200–270 km) broadband station before the surface wave train and could thus be isolated for study. Direct comparison of spectral amplitudes of presurface wave arrivals shows that M ∼ 5 explosions and earthquakes deliver the same peak dynamic stresses into the near-source crust. We conclude that a static stress change model can readily explain observed aftershock patterns, whereas it is difficult to attribute near-source triggering to a dynamic process because of the dearth of aftershocks near large explosions.

Journal of Geophysical Research B: Solid Earth↗

USGS1969

Application of deep electrical soundings for groundwater exploration in Hawaii

Forty-five resistivity soundings, using Schlumberger and equatorial dipole electrode configurations, were made on the islands of Oahu and Hawaii to determine the applicability of direct current resistivity methods for locating freshwater aquifers in the State of Hawaii. The soundings were made on the northwestern part of the island of Oahu near the town of Waialua and on the island of Hawaii on the "saddle" area near Pohakuloa and Humuula. Interpretation of 32 sounding curves obtained on the island of Oahu indicates that it is possible to correlate five stratigraphic units underlain by a vesicular basalt basement and that the determination of the approximate depth to the freshwater-saline-water interface within the basalt is feasible. Two of these Schlumberger soundings with electrode spacings AB/2 reaching 6000 ft yielded sounding curves of the maximum and minimum types whose terminal branches asymptotically approach a resistivity of about 30 ohm, which is believed to be the true resistivity of basalt saturated with sea water. Near the town of Waialua the aquifer is a coral zone as well as parts of the weathered vesicular basalt basement. On the island of Hawaii, near Pohakuloa, an exploratory well drilled in basalt to a depth of 1001 ft (prior to the resistivity survey) proved to be dry. Interpretation of thirteen deep soundings made with Schlumberger and equatorial arrays suggests that the minimum depth to a conductive layer, which may represent basalt saturated with fresh water, is about 2700 ft below land surface. The groundwater appears to be dike impounded.

Hawaii↗

USGS2009

Observations of periglacial landforms in Utopia Planitia with the High Resolution Imaging Science Experiment (HiRISE)

The region of western Utopia Planitia (80-105 degreesE, 40-55 degrees N) displays several types of landforms similar to Earth periglacial features, including scallop-shaped depressions and networks of polygonal terrains. The scalloped depressions have been proposed to originate from thermokarstic processes such as sublimation and/or melting of near-surface ground ice. Using HiRISE imagery, we characterize these depressions and several associated, distinct polygon networks in unprecedented morphologic and topographic detail and investigate support for an ice-based degradation process. The scalloped depressions and interior polygons and ridges are found to evolve together, mainly influenced by sublimation, local proximity of ground ice to the surface, and obliquity variations.

Journal of Geophysical Research↗

USGS1980

Mesozoic and Cenozoic structural trends under southern Bering Sea shelf

Mesozoic rocks exposed near the tip of the Alaska Peninsula form an antiformal structure that flanks the southern side of Bristol Bay basin and that can be traced with geophysical data about 700 km offshore to the vicinity of the Pribilof Islands. Upper Jurassic sandstone and Upper Cretaceous mudstone dredged from the top and flanks of this structure near the islands confirm that Mesozoic rocks extend from the Alaska Peninsula to the Bering sea margin. The southern part of the Bering Sea Shelf is underlain by several large structural basins: St. George, Amak, and Bristol Bay basins. These filled basins encompass an offshore area of about 31,000 sq km; St. George basin contains more than 10 km of strata. Reflection profiles show that the surface of the offshore antiformal structures is an angular unconformity overlain by Cenozoic beds. This unconformity can be traced toward the axes of the adjacent subshelf basins where, as a disconformity, it parallels underlying and overlying strata. Dredge data suggest that the unconformity and disconformity may be as old as middle to Late Cretaceous. The downdip trace of the unconformity in Bristol Bay basin is underlain by reflectors paralleling the contact, a relation suggesting that the basin and perhaps other shelf basins may be underlain by ancient Mesozoic depocenters. The bulk of the thick sections in these basins is, however, thought to be mainly Cenozoic in age. Strata in the basins are cut by high-angle growth faults. The faults commonly offset the seafloor, which implies that basin subsidence and filling continue to the present. Shallow-water diatomaceous mudstone of Eocene and Oligocene age dredged from the continental slope near the Pribilof Islands indicates that collapse of the margin and outer shelf basins began by at least early Tertiary time. In Mesozoic time, the Bering margin between Siberia and the Alaska Peninsula (Beringian margin) may have been a zone of either oblique underthrusting or transform motion between the North American and Pacific lithosphere (Kula plate?). This motion may have rifted the edge of the North American plate, resulting in the formation of a series of elongate basins and ridges paralleling the plate edge. These hypothetical basins may have controlled the location and initial subsidence of Bristol Bay, Amak, and St. George basins. Formation of the Aleutian Island arc in late Mesozoic or earliest Tertiary time presumably terminated plate interaction along the Beringian margin. Sediment loading and subsequent subsidence of the remnant plate within the abyssal Bering Sea may have caused continuing collapse of the Beringian margin in latest Cretaceous and earliest Tertiary time.

AAPG Bulletin↗

USGS2025

Completion summary for monitor wells NRF-17 and NRF-18 at the Naval Reactors Facility, Idaho National Laboratory, Idaho

The U.S. Geological Survey (USGS)—in cooperation with the U.S. Department of Energy (DOE) for the Naval Reactors Laboratory Field Office that supports operations for the Naval Reactors Facility (NRF) located at the Idaho National Laboratory (INL)—drilled and constructed well NRF-17 (formerly borehole USGS 151) and well NRF-18 (formerly borehole USGS 152) for stratigraphic framework analyses and water-quality monitoring at the Idaho National Laboratory (INL) near the NRF, in southeastern Idaho. Borehole USGS 151 was continuously cored from about 48 to 1,070 feet (ft) below land surface (BLS); rotary drilled from approximately 1,070 to 1,720 ft BLS; and re-drilled to complete construction as a monitor well NRF-17, completed to 461 ft BLS. Borehole USGS 152 was continuously cored from approximately 19 to 1,259 ft BLS; rotary drilled from approximately 1,259 to 1,630 ft BLS; and re-drilled to complete construction as a monitor well NRF-18, completed to 450 ft BLS. Geophysical data were examined with photographed core material to record lithologic descriptions and to suggest zones where groundwater flow was anticipated. Basalt flows varied from highly fractured to dense, with high-to-low vesiculation. Well NRF-17 generally was constructed in mostly dense basalt (greater than 75 percent), and well NRF-18 was constructed in primarily fractured and (or) vesicular basalt. In well NRF-17, the well capacity is directly affected by the limited amount of fractured basalt, which serves as the primary pathway for groundwater. This effect was observed during the pumping test conducted after the well's final construction. Single-well aquifer tests were done at wells NRF-17 and NRF-18 to provide estimates of transmissivity and hydraulic conductivity after final well construction and initial well development. Estimated values of transmissivity and hydraulic conductivity for well NRF-17 were 8.81 feet squared per day (ft 2 /d) and 1.04×10 -2 feet per day (ft/d), respectively. Estimated values of transmissivity and hydraulic conductivity for well NRF-18 were 4.77×10 3 ft 2 /d and 5.61 ft/d, respectively. The NRF-17 pump test resulted in 19.41 ft of measured drawdown at a sustained average pumping rate of 3.3 gallons per minute (gal/min). The NRF-18 pump test resulted in 0.55 ft of measured drawdown at a sustained average pumping rate of 31.0 gal/min. Water-quality samples collected from the two wells were analyzed for cations, anions, metals, nutrients, volatile organic compounds, stable isotopes, and radionuclides. Water samples for select inorganic constituents showed concentrations consistent with signatures from tributary valley groundwater with influences from ephemeral surface-water recharge from the Big Lost River. Water-quality samples analyzed for stable isotopes of oxygen and hydrogen are consistent with signatures from tributary valley groundwater and surface-water recharge inputs to the aquifer. No measured water-quality results were greater than their respective maximum contaminant levels for public drinking-water supplies. Inorganic and nutrient water-quality results for well NRF-17 and well NRF-18 suggest the groundwater in this area is potentially affected by industrial wastewater disposal.

Idaho↗

USGS1996

A quantitative look at the demise of a basaltic vent: The death of Kupaianaha, Kilauea Volcano, Hawai'i

The Kupaianaha vent, the source of the 48th episode of the 1983-to-present Pu'u 'O'o-Kupaianaha eruption, erupted nearly continuously from July 1986 until February 1992. This investigation documents the geophysical and geologic monitoring of the final 10 months of activity at the Kupaianaha vent. Detailed very low frequency (VLF) electromagnetic profiles across the single lava tube transporting lava from the vent were used to determine the cross-sectional area of the molten lava within the tube. Combined with measurements of lava velocity, these data provide an estimate of the lava output of Kupaianaha. In addition, lava temperatures (calculated from analysis of quenched glass) and bulk-rock chemistry were obtained for samples taken from the tube at the same site. The combined data set shows the lava flux from Kupaianaha vent declining linearly from 250000 m3/day in April 1991 to 54000 m3/day by November 1991. During that time surface breakouts of lava from weak points along the tube occurred progressively closer to the vent, consistent with declining efficiency in lava transport. There were no significant changes in lava temperature or in bulk MgO content during this period. Another eruptive episode (the 49th) began uprift of Kupaianaha on 8 November 1991 and erupted lava concurrently with Kupaianaha for 18 days. Lava flux from Kupaianaha decreased in response to this new episode, but the response was delayed by approximately 1 day. After 14 November 1991, lava velocities were no longer measurable in the tube because the lava stream beneath the skylight had crusted over; however, the VLF-derived electrical conductances documented the decreasing flux of molten lava through the tube. Kupaianaha remained active, but output continued to decrease until early February 1992 when the last active surface flows were seen. In November 1991 we used the linearly decreasing effusion rate to accurately predict the date for the death of the Kupaianaha vent. The linear nature of the decline in lava tube conductance and the delayed and slow response of the Waha'ula tube conductances to the 49th eruptive episode led us to speculate that (a) the Kupaianaha vent shut down because of a decrease in driving pressure and not because of a freeze-up of the vent, and (b) that Pu'u 'O'o, episode 49, and Kupaianaha were fed nearly vertically from a source deep within the rift zone.

Bulletin of Volcanology↗

USGS1999

Fish-community composition in Cowanesque River upstream and downstream of the Cowanesque Dam, Tioga County, Pennsylvania, 1998

Between February 1997 and September 1997, 10 monitor wells were drilled near the site of the former Naval Air Warfare Center, Warminster, Bucks County, Pa., to monitor water levels and sample ground-water contaminants in the shallow, intermediate, and deep water-bearing zones. The sampling will determine the horizontal and vertical distribution of contaminated ground water migrating from known or suspected contaminant sources. Four wells were drilled north of the property adjacent to Area A, three wells along strike located on Lewis Drive, and three wells directly down dip on Ivyland Road. Well depths range from 69 feet to 300 feet below land surface. Borehole-geophysical logging and television surveys were used to identify water-bearing zones so that appropriate intervals could be screened in each monitor well. Geophysical logs were obtained at the 10 monitor wells. Borehole television surveys were obtained at the four monitor wells adjacent to Area A. Caliper and borehole television surveys were used to locate fractures, inflections on fluidtemperature and fluid-resistivity logs were used to locate possible water-bearing fractures, and heatpulse- flowmeter measurements verified these locations. Natural-gamma logs provided information on stratigraphy. After interpretation of geophysical logs, borehole television surveys, and driller?s logs, all wells were screened such that water-level fluctuations could be monitored and water samples collected from discrete water-bearing zones in each borehole.

Open-File Report↗

USGS2026

Shallow hydrogeologic framework of the Tully Valley mudboil area, Onondaga County, New York

Mudboils have been documented in the Tully Valley in southern Onondaga County, New York, since the late 1890s. Sediment-laden water from the mudboils flows into Onondaga Creek, which empties into Onondaga Lake at Syracuse 15 miles to the north. Turbidity from the mudboils has degraded the water quality of Onondaga Creek despite a series of mitigation efforts that began in the early 1990s. Turbidity mitigation actions presently (2025) being considered include creek relocation and offline sediment settling. In support of these proposed actions during 2021–23, the U.S. Geological Survey, in cooperation with the New York State Department of Environmental Conservation, U.S. Environmental Protection Agency, Onondaga Nation, Onondaga Environmental Institute, and Central New York Regional Planning and Development Board, collected and analyzed geologic, hydrologic, geophysical, and geotechnical data to characterize the shallow hydrogeology along four proposed creek-relocation paths and in the proposed offline settling basin area. The investigation indicated that the four proposed creek-relocation paths, two east of Onondaga Creek and two west of Onondaga Creek, are underlain by sediments including muck, alluvium, mudboil deposits, alluvial-fan sand and gravel, and lacustrine fines. The proposed excavations would penetrate partially to fully saturated conditions: generally, the water table is shallow near the creek and deep on the alluvial fans. The shallowest excavation, about 5 feet below land surface, would be near the creek and primarily in alluvium, and the deepest excavation, as much as 30 feet below land surface, would be in the alluvial-fan deposits. Brackish waters would be penetrated by proposed channel excavations on the eastern side of Onondaga Creek in an area downgradient from a potentially leaking historical salt-exploration borehole and near the main mudboil area. Excavation in these areas likely would provide a continuous source of brackish groundwater to the relocated creek. Proposed channel excavations of muck, soft to very soft lacustrine fines, and mudboil-type sediments in mudboil and suspected mudboil areas would pose an excavation and slope stability challenge and would have the greatest potential to create new mudboils. Proposed channel excavations below the water table on the Rattlesnake Gulf and Rainbow Creek alluvial fans would intercept groundwater and make the constructed streambank susceptible to seepage-induced slope instability. The substantial water-level fluctuation in the sediments of both alluvial fans would aggravate the stability condition. In addition, excavation on the Rattlesnake Gulf alluvial fan would have the potential to affect water-supply springs at the toe of the fan. The proposed offline settling basin area is in the northern part of the Rattlesnake Gulf alluvial fan. Natural and man-made diversions of Rattlesnake Gulf have resulted in saturated conditions in the general area of the proposed basin. The proposed offline settling basin would be excavated in, and berms would be constructed on, alluvial-fan deposits and lacustrine fines. In the proposed basin area, the alluvial deposits overlying the lacustrine fines are less than 10 feet thick. Excavation, berm construction, and loading of the saturated, soft to very soft lacustrine fines may be problematic and require soil strengthening.

New York↗