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USGS2020

USGS “Did You Feel It?” — Science and lessons from twenty years of citizen science-based macroseismology

The U.S. Geological Survey (USGS) “Did You Feel It?” (DYFI) system is an automatic method for rapidly collecting macroseismic intensity data from Internet users’ shaking and damage reports and for generating intensity maps immediately following felt earthquakes. DYFI has been in operation for nearly two decades (1999-2019) in the United States, and for nearly 15 years globally. During that period the amount of data collected is astounding: Over 5 million individual DYFI intensity reports—spanning all magnitude and distance ranges—have been amassed and archived. DYFI allows for macroseismic data collection at rates and quantities never before imagined, and thus high-quality macroseismic intensity maps can be made almost immediately, and with more complete coverage at higher resolution than in the past. DYFI also allows for valuable positive interactions of the citizenry with a Federal science agency. In essence, the widespread adoption of DYFI—along with ShakeMap—has facilitated the general acceptance of the very concept of shaking intensity, fundamentally improving our agency’s ability to communicate both hazard and risk to the population. DYFI effectively confirms the importance of reporting and inculcating the public’s understanding of intensity—in addition to magnitude—for a proper perspective of earthquake risk-related decision-making. Furthermore, the vast amount of DYFI data allow for data-rich analyses of otherwise intractable seismological, sociological, and earthquake impact studies that range from quantifying the shaking due to induced earthquakes, to human response and risk perception, to relating recorded shaking metrics to macroseismic effects, and the attenuation of intensity with magnitude and distance. Naturally, web-based data collection also poses challenges. After two decades of experience acquiring data with the DYFI system, we address some of these hallenges by documenting refinements to our algorithmic and operational procedures that have evolved over that time. Lastly, we outline new opportune research and development directions for our DYFI approach to citizen seismology.

Frontiers in Earth Science↗
USGS1986

Hydrology of the Price River basin, Utah, with emphasis on selected coal-field areas

Data obtained during a hydrologic study of the Price River basin, Utah, are used to describe seasonal variations off low of springs, relation between ground water and surface water, hydraulic properties of the ground-water reservoir, ground-water recharge and discharge, flood characteristics of streams, mineralogic composition and depositional rates of sediments, nutrient and inorganic loading in streams and Scofield Reservoir, and water budgets for selected basins. Additional study and monitoring are needed to detect possible hydrologic changes caused by coal mining. Much of the ground-water discharge from the Star Point Sandstone in the Mesaverde Group in the Wasatch Plateau occurs along faults. In the Book Cliffs, where faulting is less extensive, most of the ground-water discharge is from the Flagstaff Limestone. The Flagstaff Limestone is greatly diffusive, has a small storage coefficient, and contains water which is perched. Springs issuing from the Star Point Sandstone in the Mud Creek drainage (Wasatch Plateau) had recession indexes greater than 365 days per log cycle. Springs issuing at higher altitudes from the Colton Formation and the Flagstaff Limestone in the Soldier Creek area (Book Cliffs) have great seasonal variability, with recession indexes ranging from 24 to 115 days per log cycle. Estimated transmissivities in the Soldier Creek area ranged from 0.003 foot squared per day in the lower part of the Castlegate Sandstone to 0.07 foot squared per day in the Price River Formation. Seepage from the Star Point Sandstone is the major contributor to base flow of the stream in Eccles Canyon (Wasatch Plateau). Gains of as much as 230 gallons per minute occurred near a fault zone which crosses Eccles Canyon at the junction with South Fork Canyon. The potentiometric surface of water in the Blackhawk Formation in the Wasatch Plateau (Mud Creek drainage) and the Book Cliffs (Soldier Creek area) generally is above the coal zones, and dewatering will be necessary in most places during mining. The total reported mine discharge during 1980 was about 2,800 acre-feet. During the 1980 water year, ground-water discharge from the Flagstaff Limestone contributed about 4,400 acre-feet, or 41 percent of the combined streamflow of Coal, Soldier, and Dugout Creeks. Discharge from the Blackhawk and other formations contributed about 2,200 acrefeet, or 21 percent of the streamflow. The recharge to a 4,020-acre outcrop of the Flagstaff Limestone in the Soldier Creek area was determined from measurements of the discharge of springs and seepage gains in streams. The estimated recharge was 2 inches per year, or 12 percent of the April 1 snowpack, or 9 percent of the precipitation during 1980. Benthic-diversity indexes at streams in the Book Cliffs and Wasatch Plateau are related to the size of the bed material. The Shannon-Weiner diversity index for five sites in the Mud Creek drainage ranged from 1.57 to 4.'20 during four sampling periods in 1979-80. In the Soldier Creek drainage, the diversity index for four sampling sites ranged from 0.8 to 2.3 during three sampling periods in 1979-80. Sediment deposition in Scofield Reservoir during 1943-79 was estimated to be 3,000 acre-feet but most of the coal deposition in the reservoir occurred prior to about 1950. An anaerobic zone develops in the reservoir during the summer, but water in the reservoir completely mixes during late summer or early fall.

Utah↗
USGS1983

Hydrology of the Price River basin, Utah, with emphasis on selected coal-field areas

Data obtained during a hydrologic study of the Price River basin, Utah, are used to describe seasonal variations of flow of springs, relation between ground water and surface water, hydraulic properties of the ground-water reservoir, ground-water recharge and discharge, flood characteristics of streams, mineralogic composition and depositional rates of sediments, nutrient and inorganic loading in streams and Scofield Reservoir, and water budgets for selected basins. Additional study and monitoring are needed to detect possible hydrologic changes caused by coal mining. Much of the ground-water discharge from the Star Point Sandstone in the Mesaverde Group in the Wasatch Plateau occurs along faults. In the Book Cliffs, where faulting is less extensive, most of the ground-water discharge is from the Flagstaff Limestone. The Flagstaff Limestone is greatly diffusive, has a small storage coefficient, and contains water which is perched. Springs issuing from the Star Point Sandstone in the Mud Creek drainage (Wasatch Plateau) had recession indexes greater than 365 days per log cycle. Springs issuing at higher altitudes from the Colton Formation and the Flagstaff Limestone in the Soldier Creek area (Book Cliffs) have great seasonal variability, with recession indexes ranging from 24 to 115 days per log cycle. Estimated transmissivities in the Soldier Creek area ranged from 0.003 foot squared per day in the lower part of the Castlegate Sandstone to 0.07 foot squared per day in the Price River Formation. Seepage from the Star Point Sandstone is the major contributor to base flow of the stream in Eccles Canyon (Wasatch Plateau). Gains of as much as 230 gallons per minute occurred near a fault zone which crosses Eccles Canyon at the junction with South Fork Canyon. The potentiometric surface of water in the Blackhawk Formation in the Wasatch Plateau (Mud Creek drainage) and the Book Cliffs (Soldier Creek area) generally is above the coal zones, and dewatering will be necessary in most places during mining. The total reported mine discharge during 1980 was about 2,800 acre-feet. During the 1980 water year, ground-water discharge from the Flagstaff Limestone contributed about 4,400 acre-feet, or 41 percent of the combined streamflow of Coal, Soldier, and Dugout Creeks. Discharge from the Blackhawk and other formations contributed about 2,200 acre-feet, or 21 percent of the streamflow. The recharge to a 4,020-acre outcrop of the Flagstaff Limestone in the Soldier Creek area was determined from measurements of the discharge of springs and seepage gains in streams. The estimated recharge was 2 inches per year, or 12 percent of the April 1 snowpack, or 9 percent of the precipitation during 1980. Benthic-diversity indexes at streams in the Book Cliffs and Wasatch Plateau are related to the size of the bed material. The Shannon-Weiner diversity index for five sites in the Mud Creek drainage ranged from 1.57 to 4.20 during four sampling periods in 1979-80. In the Soldier Creek drainage, the diversity index for four sampling sites ranged from 0.8 to 2.3 during three sampling periods in 1979-80. Sediment deposition in Scofield Reservoir during 1943-79 was estimated to be 3,000 acre-feet but most of the coal deposition in the reservoir occurred prior to about 1950. An anaerobic zone develops in the reservoir during the summer, but the water in the reservoir completely mixes during late summer or early fall.

Utah↗
USGS1983

Mineral surveys by the Geological Survey and the Bureau of Mines of Bureau of Land Management Wilderness Study Areas

The Federal Land Policy and Management Act of 1976 instructed the Bureau of Land Management (BLM) to review all public lands under its jurisdiction and to determine their suitability or nonsuitability for wilderness designation. As part of this process, the Geological Survey and the Bureau of Mines conduct mineral surveys of areas for which a preliminary determination of wilderness suitability has been made. The BLM has completed its wilderness inventory phase and has found that 23.2 million acres deserve further study for wilderness consideration. These 23.2 million acres of wilderness study areas include 1 million acres of natural and primitive areas (Instant Study Areas), 5.7 million acres in the California Desert Conservation Area, and 16.5 million acres in other wilderness study areas. Mineral surveys on all areas recommended for wilderness will be completed by 1990.

Circular↗
USGS2007

Geologic map of Nevada

The purpose of the Geologic Map of Nevada is to provide an integrated set of digital geologic information that can be used for regional geologic and rigorous spatial analysis. Two components of this map represent new information that has not been published in this form before. The new geology layer was created by merging into a single file individual digital Nevada county geologic maps (Hess and Johnson, 1997), published at a scale of 1:250,000. A new regional interpretation was created to unify all of the different county rock units, and then appropriate edits and modifications were made to the file to reflect additional geologic information and more current geologic interpretations. All possible sources of information were not utilized in the scope of this project, but rather the goal was to create a consistent Statewide 1:250,000-scale map that would facilitate regional geologic interpretation and be a foundation for future spatial analyses of digital data. Secondly, a new database of conodont biostratigraphic data compiled and analyzed by Anita Harris is also incorporated into the map. Information about many, but not all, of these conodont samples have been published separately elsewhere over the years, but they have not been presented together in a single digital database. Other previously published data layers are used in this map to enhance the usefulness of the geologic information. These layers include mineral deposit locations, oil well locations, and cartographic layers such as county boundaries, roads, towns, cities, rivers, water bodies, township, range and section grids, quadrangle grids, and topography. A summary of these components is given below, and complete descriptions of each layer are provided in the digital metadata.

Nevada↗
USGS1964

Placer gold occurrences in Alaska

The following references give data on localities of placer gold by quadrangle and are keyed by number within each quadrangle to locations shown on map. The quadrangle boundaries and names used on the map are those selected by the U. S. Geological Survey for topographic mapping in Alaska on a scale of 1:250,000. The references cited for each group of localities are the most complete or most recent descriptions as of December 31, 1960.

Alaska↗
USGS1977

Particle size of sediments collected from the bed of the Amazon River and its tributaries in June and July 1976

Sixty-five samples of bed material were collected from the Amazon River and its major tributaries between Belem, Brazil, and Iquitos, Peru. Samples were taken with a standard BM-54 sampler, a pipe dredge, or a Helley-Smith bedload sampler. Most of the samples have median diameters in the size range of fine to medium sand and contain small percentages of fine gravel. Complete size distributions are tabulated.

Open-File Report↗
USGS1980

Geologic and hydrologic data from a test-monitor well at Fernandina Beach, Florida

A 2,102-foot observation well was drilled at Fernandina Beach, Florida, to obtain geologic and hydrologic data. Drill cuttings, water samples, and water-level measurements were collected. Geologist's, driller's, and geophysical logs were completed. The well is constructed with 12-inch diameter casing to a depth of 515 feet and 6-inch diameter casing from 515 to 2,000 feet. The remainder is open hole. The uppermost 500 feet of material penetrated by the well consists of sand, clay, limestone, and dolomite. In the remainder of the hole, the material consists of fragmental and granular limestone and massive to finely crystalline dolomite, which comprise the Floridan aquifer in the area. After the well was completed, water levels in the monitored zone, 2,000 to 2,102 feet, were above land surface. During July and August 1979, water levels ranged from about 8 to 13 feet above land surface. Chloride concentrations of water sampled through the drill stem from a depth of 632 to 2,039 feet ranged from 25 to 710 milligrams per liter. Chloride increased markedly below 2,039 feet to a maximum of 7,800 milligrams per liter at 2,094 feet. After completion of the well, chloride was 8,100 milligrams per liter.

Florida↗
USGS1987

Estimated sediment deposition in Lake Corpus Christi, Texas, 1972-85

The investigation of sediment deposition in Lake Corpus Christi was initiated by researching the published and unpublished sediment data for the 1972-85 water years for stations located upstream and downstream of the lake. Regression analysis was used to fill in the missing data. Data were tabulated for monthly discharge (acre-feet) and sediment load (tons, acre-feet, and percent by weight). Yearly totals and cumulative averages were computed and included in the tables. An estimated 10,300 acre-feet (wet volume) of sediment has been deposited in Lake Corpus Christi during the 14-year period of record (1972-85), an average of 736 acre-feet per year (wet volume). An earlier study by the U.S. Soil Conservation Service, based on 1942-48 changes of lake bottom contours, estimated that 736 acre-feet per year of suspended sediment had entered Lake Corpus Christi during that 6-year period. Some difference was found in comparison of the results of the U.S. Geological Survey (Water Resources Division) study and the McCaughan and Etheridge Consulting Engineers study. Total sediment outflow from Lake Corpus Christi was estimated at 177 acre-feet (dry) by the Geological Survey and 1,070 acre-feet (dry) by McCaughan and Etheridge Consulting Engineers. This difference may be due to construction of a new dam, completed in 1958, that is higher and inundated the old dam.

Open-File Report↗
USGS1990

Solid-precipitation (snowfall) measurement intercomparison, Bismarck, North Dakota

Difficulties involved in obtaining accurate measurements of solid precipitation (snowfall) have been recognized for many years. Many studies have been conducted to evaluate the accuracy and performance of precipitation gages. These studies show that the type of collection method used can significantly affect the quantity of precipitation measured. Although the types of collection methods evaluated differed for each study and the magnitude of measurement error differed for each study, all of the studies concluded that wind is the major cause of measurement error. Measurement error caused by wind is the result of turbulence and wind speed in the vicinity of the gage orifice (opening). As air rises to pass over the gage, precipitation particles that would have entered the gage orifice are deflected and carried farther downwind. Measurement errors increase as wind speed increases. Studies have shown that measurement errors as great as 80 percent can be attributed to wind. Wind speed and turbulence can be reduced by shielding the gage from the wind. Several types of windshields have been built to decrease wind-related errors. The World Meteorological Organization recognized the need for an international comparison of current methods used for measuring solid precipitation and proposed the Solid Precipitation Measurement Intercomparison. The objectives of the Intercomparison are to: Determine the wind-related errors in methods of solid-precipitation measurements; Derive standard methods for correcting solid-precipitation measurements; Introduce a reference method of solid-precipitation measurement for general use to calibrate any type of precipitation gage; and Establish a complete solid-precipitation data set

Open-File Report↗
USGS1996

Snow-depth and water-equivalent data for the Fairbanks area, Alaska, spring 1995

Snow depths at 34 sites and snow-water equivalents at 13 sites in the Fairbanks area were monitored during the 1995 snowmelt period (March 30 to April 26) in the spring of 1995. The U.S. Geological Survey conducted this study in cooperation with the Fairbanks International Airport, the University of Alaska Fairbanks, the Alaska Department of Natural Resources-Division of Mining and Water Management, the U.S Army, Alaska, and the U.S. Army Corps of Engineers-Alaska District. These data were collected to provide information about potential recharge of the ground-and surface-water systems during the snowmelt period in the Fairbanks area. This information is needed by companion geohydrologic studies of areas with known or suspected contaminants in the subsurface. Data-collection sites selected had open, boggy, wooded, or brushy vegetation cover and had different slope aspects. The deepest snow at any site, 27.1 inches, was recorded on April 1, 1995; the shallowest snow measured that day was 19.1 inches. The snow-water equivalents at these two sites were 5.9 inches and 4.5 inches, respectively. Snow depths and water equivalents were comparatively greater at open and bog sites than at wooded or brushy sites. Snow depths and water equivalents at all sites decreased throughout the measuring period. The decrease was more rapid at open and boggy sites than at wooded and brushy sites. Snow had completely disappeared from all sites by April 26, 1995.

Open-File Report↗
USGS1979

Streamflow simulation studies of the Hillsborough, Alafia, and Anclote Rivers, west-central Florida

A modified version of the Georgia Tech Watershed Model was applied for the purpose of flow simulation in three large river basins of west- central Florida. The model was calibrated for six streamflow stations located in these basins using 4 years of historical and current rainfall, runoff, and estimated evapotranspiration data. Watersheds modeled range in size from about 70 to 650 square miles. Calibrations were evaluated by comparing the following synthesized and observed data: annual hydrographs for the 1959, 1960, 1973 and 1974 water years, flood hydrographs (maximum daily discharge and flood volume), and long-term annual flood-peak discharges (1950-72). Annual hydrographs, excluding the 1973 water year, were compared using average absolute error in annual runoff and daily flows and correlation coefficients of monthly and daily flows. For stations used in the study, average absolute errors in simulated runoff range from 9 to 21 percent and errors in daily flows range from 48 to 71 percent. Correlation coefficients for monthly flows range from 0.81 to 0.95 and correlation coefficients for daily flows range from 0.68 to 0.87. Correlation coefficients for simulated and observed maximum daily discharges and flood volumes used for calibration range from 0.91 to 0.98 and average standard errors of estimate range from 18 to 45 percent. Cor-relation coefficients for simulated and observed annual flood-peak dis-charges range from 0.60 to 0.74 and average standard errors of estimate range from 33 to 44 percent. The number of flood events used for calibration varies for each streamflow station, but range from 6 to 18. The number of annual flood-peak discharges used also vary but average about 20 for each station. On the basis of these results, it is concluded that flood calibrations have been achieved for stations used in this study; however, because of data limitations, calibrations and prediction errors cannot be completely verified until additional rainfall, runoff, and evapotranspiration data become available.

Florida↗
USGS1981

Impact of suburban residential development on water resources in the area of Winslow Township, Camden County, New Jersey

Surface-water and ground-water quality, streamflow, and data on ground-water levels in the upper Great Egg Harbor River basin in the vicinity of the Winslow Crossing residential development in Winslow Township are evaluated. The data include continuous streamflow at four sites, monthly stream water quality at seven sites, ground-water levels and periodic ground-water quality in four wells from 1972 through 1978. Pumpage from the Cohansey Sand in the study area was lower than anticipated because of a slowdown in construction. The average pumpage of 0.48 million gallons per day during 1978 had little effect on ground-water levels. Dissolved-solids concentrations were lower in a well upgradient from the urbanized area. Elevated levels of dissolved solids, specific conductance, chloride, nitrate, and phosphorus were found in the shallow ground water in the vicinity of the Winslow wastewater treatment plant because of effluent infiltration ponds. Nitrate was greatly reduced in October 1974 by a change in the treatment process, which increased denitrification. Phosphorus concentrations in the ground water remained elevated, however. Water from the most urbanized drainage basin was a magnesium bicarbonate type, while the less developed basins had sodium chloride sulfate type waters. Water from the two developed basins had higher median pH (7.1) compared with that of the other basins (5.6-6.3). Winslow Crossing’s development had only a slight effect on the quality of water in Great Egg Harbor River. The river receives point and non-point discharges upstream from Winslow Crossing, and the quality of the water generally improves as the river flows downstream. Streamflow and rainfall were slightly above normal. Unit hydrograph analysis of one basin showed an 80 percent increase in the peak discharge of a 60-minute unit hydrograph (from approximately 150 to 270 cubic feet per second) after the development of 14 percent of the basin. Installation of a stormwater detention basin reduced the peak discharge to 220 ft 3 /s. Sediment discharge from this basin averaged 0.24 tons/d/mi 2 during construction but decreased to the preconstruction level of 0.06 tons/d/mi 2 after the completion of construction and the installation of the detention basin.

New Jersey↗
USGS1996

Surface-water-quality assessment of the lower Kansas River basin, Kansas and Nebraska: Results of investigations, 1987-90

Analysis of surface-water-quality data has enabled an assessment of water-quality conditions and trends and their relation to human and natural factors in the lower Kansas River basin, Kansas and Nebraska. This basin drains 15,300 square miles of predominantly agricultural land and is one of seven pilot studies completed as part of the National Water-Quality Assessment Program.

Kansas, Nebraska↗
USGS2009

Occurrence of Selected Organic Compounds in Groundwater Used for Public Supply in the Plio-Pleistocene Deposits in East-Central Nebraska and the Dawson and Denver Aquifers near Denver, Colorado, 2002-2004

The National Water-Quality Assessment Program of the U.S. Geological Survey has an ongoing Source Water-Quality Assessment program designed to characterize the quality of water in aquifers used as a source of drinking-water supply for some of the largest metropolitan areas in the Nation. In addition to the sampling of the source waters, sampling of finished or treated waters was done in the second year of local studies to evaluate if the organic compounds detected in the source waters also were present in the water supplied to the public. An evaluation of source-water quality used in selected groundwater-supplied public water systems in east-central Nebraska and in the south Denver metropolitan area of Colorado was completed during 2002 through 2004. Fifteen wells in the Plio-Pleistocene alluvial and glacial deposits in east-central Nebraska (the High Plains study) and 12 wells in the Dawson and Denver aquifers, south of Denver (the South Platte study), were sampled during the first year to obtain information on the occurrence and distribution of selected organic chemicals in the source waters. During the second year of the study, two wells in east-central Nebraska were resampled, along with the associated finished water derived from these wells, to determine if organic compounds detected in the source water also were present in the finished water. Selection of the second-phase sampling sites was based on detections of the most-frequently occurring organic compounds from the first-year Source Water-Quality Assessment study results. The second-year sampling also required that finished waters had undergone water-quality treatment processes before being distributed to the public. Sample results from the first year of sampling groundwater wells in east-central Nebraska show that the most-frequently detected organic compounds were the pesticide atrazine and its degradate, deethylatrazine (DEA, otherwise known as 2-chloro-4-isopropylamino-6-amino-s-triazine or CIAT), which were detected in 9 of the 15 wells (60 percent of the samples). The second most frequently detected organic compound was tetrachloroethylene, detected in 4 of the 15 wells (27 percent of the samples), followed by chloroform, trichloroethylene, and 2-hydroxyatrazine (2-hydroxy-4-isopropylamino-6-ethylamino-s-triazine, or OIET), present in 3 of the 15 wells (20 percent of the samples). The pesticide compounds deisopropylatrazine (2-chloro-6-ethylamino-4-amino-s-triazine, or CEAT), metolachlor, and simazine and the volatile organic compound cis-1,2-dichloroethylene were detected in 2 of the 15 wells, and the compounds diuron and 1,2-dichloroethane were detected in only 1 of the 15 wells during the first-year sampling. Most detections of these compounds were at or near the minimum reporting levels, and none were greater than their regulatory maximum contaminant level. There were few detections of organic compounds during the first year of sampling groundwater wells in the South Platte study area. The compounds atrazine, deethylatrazine, picloram, tetrachloroethylene, methyl-tert-butyl-ether (MTBE), tris(2-butoxyethyl)phosphate, and bromoform were detected only once in all the samples from the 12 wells. Most detections of these compounds were at or near the minimum reporting levels, and none were greater than their regulatory maximum contaminant level. Second-year sampling, which included the addition of paired source- and finished-water samples, was completed at two sites in the High Plains study area. Source-water samples from the second-year sampling had detections of atrazine and deethylatrazine; at one site deisopropylatrazine and chloroform also were detected. The finished-water samples, which represent the source water after blending with water from other wells and treatment, indicated a decrease in the concentrations of the pesticides at one site, whereas concentrations remained nearly constant at a second site. The trihalomethanes (THMs or disinfec

Scientific Investigations Report↗
USGS2012

Construction diagrams, geophysical logs, and lithologic descriptions for boreholes USGS 103, 105, 108, 131, 135, NRF-15, and NRF-16, Idaho National Laboratory, Idaho

This report, prepared in cooperation with the U.S. Department of Energy, summarizes construction, geophysical, and lithologic data collected from about 4,509 feet of core from seven boreholes deepened or drilled by the U.S. Geological Survey (USGS), Idaho National Laboratory (INL) Project Office, from 2006 to 2009 at the INL. USGS 103, 105, 108, and 131 were deepened and cored from 759 to 1,307 feet, 800 to 1,409 feet, 760 to 1,218 feet, and 808 to 1,239 feet, respectively. Boreholes USGS 135, NRF-15, and NRF-16 were drilled and continuously cored from land surface to 1,198, 759, and 425 feet, respectively. Cores were photographed and digitally logged by using commercially available software. Borehole descriptions summarize location, completion date, and amount and type of core recovered.

Idaho↗
USGS1983

AIRYROOT: A Fortran program for calculating the gravitational attraction of an Airy isostatic root out to 166.7 km

This report describes a FORTRAN-77 program called AIRYROOT which calculates the gravitational attraction at sea level of an Airy isostatic root extending out to a radius of 166.7 km. The program incorporates an efficient algorithm devised by Parker (1912) which uses the fast Fourier transform to calculate potential field anomalies. Input is a rectangular grid in a projected coordinate system which contains values describing topography (elevations and depths in meters) or surface load (mass in g/cm2). Output is a rectangular grid of values of the gravitational attraction of the root in milligals (mGal). A strategy is outlined for combining this output with published results describing the attraction of the root beyond 166.7 km, for upward continuing the total attraction to appropriate observation elevations, and for subtracting the result from Bouguer gravity data to produce an isostatic residual gravity map. This program can also be used to make complete Bouguer corrections to marine gravity data given appropriate bathymetric data sets.

Open-File Report↗
USGS1987

Fate and movement of azaarenes and their anaerobic biotransformation products in an aquifer contaminated by wood-treatment chemicals

Infiltration of wastes containing creosote and pentachlorophenol from surface impoundments at an abandoned wood-treatment facility near Pensacola, Florida, resulted in contamination of the underlying sand and gravel aquifer. Pond sludges and sediments near the source were contaminated with 2- to 5-ring azaarenes having log Kow values of from 2.0 to 5.6. However, the ground water contained only azaarenes and their oxygenated and methylated derivatives having log Kow values of less than 3.5. These compounds also were present in coal tar-contaminated ground water at a site near St. Louis Park, Minnesota. Laboratory anaerobic degradation studies and on-site observations indicated that oxygenated azaarenes probably were biotransformation products of reactions mediated by indigenous microbial populations. Microbial N-methylation, C-methylation and O-methylation reactions are reported here for the first time. In the presence of nutrients and carbon sources such as acetate and propionate, all azaarenes studied were either partially or completely degraded. Evidence for the microbial degradation of azaarenes in ground water from anaerobic zones is presented. Oxygenated azaarenes were relatively more water-soluble, mobile and persistent in hydrogeologic environments.

Minnesota, Florida↗