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2003

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Articles 181 - 210 of 368

Full-Text Articles in Earth Sciences

Quantitative Shape Measurements Of Distal Volcanic Ash, William I. Rose, Colleen M. Riley, Gregg J. Bluth Jan 2003

Quantitative Shape Measurements Of Distal Volcanic Ash, William I. Rose, Colleen M. Riley, Gregg J. Bluth

Department of Geological and Mining Engineering and Sciences Publications

Large-scale volcanic eruptions produce fine ash (< 200 μm) which has a long atmospheric residence time (1 hour or more) and can be transported great distances from the volcanic source, thus, becoming a hazard to aircraft and public health. Ash particles have irregular shapes, so data on particle shape, size, and terminal velocities are needed to understand how the irregular-shaped particles affect transport processes and radiative transfer measurements. In this study, a methodology was developed to characterize particle shapes, sizes , and terminal velocities for three ash samples of different compositions. The shape and size of 2,500 particles from 1) distal fallout (~100 km) of the October 14, 1974 Fuego eruption (basaltic), 2) the secondary maxima (~250 km) of the August 18, 1992 Spurr eruption (andesitic), and 3) the Miocene Ash Hollow member, Nebraska (rhyolitic) were measured using image analysis techniques. Samples were sorted into 10 to 19 terminal velocity groups (0.6-59.0 cm/s) using an air elutriation device. Grain size distributions for the samples were measured using laser diffraction. Aspect ratio, feret diameter, and perimeter measurements were found to be the most useful descriptors of how particle shape affects terminal velocity. These measurement values show particle shape differs greatly from a sphere (commonly used in models and algorithms). The diameters of ash particles were 10-120% larger than ideal spheres at the same terminal velocity, indicating that irregular particle shape greatly increases drag. Gas-adsorption derived surface areas are 1 to 2 orders of magnitude higher than calculated surface areas based on measured dimensions and simple geometry, indicating that particle shapes are highly irregular. Correction factors for surface area were derived from the ash sample measurements so that surface areas calculated by assuming spherical particle shapes can be corrected to reflect more realistic values.

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Retrieval Of Mass And Sizes Of Particles In Sandstorms Using Two Modis Ir Bands: A Case Study Of April 7 2001 Sandstorm In China, Yingxin Gu, William I. Rose, Gregg J. Bluth Jan 2003

Retrieval Of Mass And Sizes Of Particles In Sandstorms Using Two Modis Ir Bands: A Case Study Of April 7 2001 Sandstorm In China, Yingxin Gu, William I. Rose, Gregg J. Bluth

Department of Geological and Mining Engineering and Sciences Publications

A thermal infrared remote sensing retrieval method developed by Wen and Rose [1994], which retrieves particle sizes, optical depth, and total masses of silicate particles in the volcanic cloud, was applied to an April 07, 2001 sandstorm over northern China, using MODIS. Results indicate that the area of the dust cloud observed was 1.34 million km2, the mean particle radius of the dust was 1.44 μm, and the mean optical depth at 11 μm was 0.79. The mean burden of dust was approximately 4.8 tons/km2 and the main portion of the dust storm on April 07, 2001 contained 6.5 million …

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Value Of Nutrients In Poultry Litter When Applied In The Fall, Monroe Rasnake, George Kelley Jan 2003

Value Of Nutrients In Poultry Litter When Applied In The Fall, Monroe Rasnake, George Kelley

Soil Science News and Views

The value of nutrients in poultry litter depends not only on how much nitrogen (N), phosphorus (P) and potassium (K) it contains, but also on how it is handled and applied. The following table compares the value of 19 poultry litter samples from Hopkins County analyzed for N, P & K and the litter then spread in the fall. The samples include pullet, breeder and broiler manures, with storage times up to one year. Nutrient values were based on a comparison with urea (46-0-0) at $199/ton, triple super phosphate (0-46-0) at $215/ton and muriate of potash (0-0-60) at $165/ton.

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A Watershed Analysis Of Threemile Pond: Implications For Water Quality And Land Use Management, Colby Environmental Assessment Team, Colby College, Problems In Environmental Science Course (Biology 493), Colby College Jan 2003

A Watershed Analysis Of Threemile Pond: Implications For Water Quality And Land Use Management, Colby Environmental Assessment Team, Colby College, Problems In Environmental Science Course (Biology 493), Colby College

Colby College Watershed Study: Threemile Pond (2003)

The 2003 Colby Environmental Assessment Team chose to study the Threemile Pond watershed. The Threemile Pond watershed is located in Vassalboro, China., Windsor, and Augusta, Maine. Threemile Pond is a popular site for recreation and is home to a wide range of flora and fauna. Like all other lakes in Maine, it is a young lake. However, intensive human activity in the watershed contributes a substantial amount of nutrients and the lake has algal blooms annually in the summer months. The purpose of this study was to assess the impact of land use and development on the water quality of …

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A Late Quaternary Record Of Eolian Silt Deposition In A Maar Lake, St. Michael Island, Western Alaska, Daniel R. Muhs, Thomas A. Ager, Josh Been, J. Platt Bradbury, Walter E. Dean Jan 2003

A Late Quaternary Record Of Eolian Silt Deposition In A Maar Lake, St. Michael Island, Western Alaska, Daniel R. Muhs, Thomas A. Ager, Josh Been, J. Platt Bradbury, Walter E. Dean

United States Geological Survey: Staff Publications

Recent stratigraphic studies in central Alaska have yielded the unexpected finding that there is little evidence for full-glacial (late Wisconsin) loess deposition. Because the loess record of western Alaska is poorly exposed and not well known, we analyzed a core from Zagoskin Lake, a maar lake on St. Michael Island, to determine if a full-glacial eolian record could be found in that region. Particle size and geochemical data indicate that the mineral fraction of the lake sediments is not derived from the local basalt and is probably eolian. Silt deposition took place from at least the latter part of the …

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Inverse Modeling Of Btex Dissolution And Biodegradation At The Bemidji, Mn Crude-Oil Spill Site, Hedeff I. Essaid, Isabelle M. Cozzarelli, Robert P. Eganhouse, William N. Herkelrath, Barbara A. Bekins, Geoffrey N. Delin, Win Butler Jan 2003

Inverse Modeling Of Btex Dissolution And Biodegradation At The Bemidji, Mn Crude-Oil Spill Site, Hedeff I. Essaid, Isabelle M. Cozzarelli, Robert P. Eganhouse, William N. Herkelrath, Barbara A. Bekins, Geoffrey N. Delin, Win Butler

United States Geological Survey: Staff Publications

The U.S. Geological Survey (USGS) solute transport and biodegradation code BIOMOC was used in conjunction with the USGS universal inverse modeling code UCODE to quantify field-scale hydrocarbon dissolution and biodegradation at the USGS Toxic Substances Hydrology Program crude-oil spill research site located near Bemidji, MN. This inverse modeling effort used the extensive historical data compiled at the Bemidji site from 1986 to 1997 and incorporated a multicomponent transport and biodegradation model. Inverse modeling was successful when coupled transport and degradation processes were incorporated into the model and a single dissolution rate coefficient was used for all BTEX components. Assuming a …

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Preliminary Investigations Of Seasonal Changes In The Geochemical Evolution Of The Logdson River, Mammoth Cave, Kentucky, Chris Groves, Darlene M. Anthony, Joe Meiman Jan 2003

Preliminary Investigations Of Seasonal Changes In The Geochemical Evolution Of The Logdson River, Mammoth Cave, Kentucky, Chris Groves, Darlene M. Anthony, Joe Meiman

Earth, Environmental, and Atmospheric Sciences Faculty Publications

Many geochemical studies have been made of karst waters worldwide. Most data that provide the framework for our current understanding of the evolution of karst waters have come from sampling at discrete times and locations, such as springs or wells. Relatively few studies have been made of the geochemical evolution of groundwater as it moves through an open flow system. This paper addresses the seasonal changes in the geochemistry of the Logsdon River conduit as it passes through nearly 10km of the carbonate aquifer of south-central Kentucky . The most important control on the ability of groundwaters to dissolve limestone …

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Natural Resource Management Issues In The Agricultural Zone Of Western Australia : South West Region, B Nicholas, Paul Galloway, Peter J. Tille, Angela Stuart-Street, Heather M. Percy Jan 2003

Natural Resource Management Issues In The Agricultural Zone Of Western Australia : South West Region, B Nicholas, Paul Galloway, Peter J. Tille, Angela Stuart-Street, Heather M. Percy

Resource management technical reports

Provides and analysis of current pressures on agricultural resources of the South West region of Western Australia. Differing ranges of risks are shown for different degradation issues because of various impacts. Each natural resource management issues covers nature and extent of susceptibility, impacts on agriculture and the environment, management options and effectiveness of management options.

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Tracer/Time-Lapse Radar Imaging Test At The Boise Hydrogeophysical Research Site, Warren Barrash, Michael D. Knoll, David W. Hyndman, Tom Clemo, Edward C. Reboulet, Elisabeth M. Hausrath Jan 2003

Tracer/Time-Lapse Radar Imaging Test At The Boise Hydrogeophysical Research Site, Warren Barrash, Michael D. Knoll, David W. Hyndman, Tom Clemo, Edward C. Reboulet, Elisabeth M. Hausrath

Geosciences Faculty Publications and Presentations

A combined tracer and time-lapse radar imaging experiment was conducted in the unconfined coarse fluvial aquifer at the Boise Hydrogeophysical Research Site in August, 2001. Two tracers (bromide and uranine) were injected to form a plume over a 4-m interval that spanned the contact between hydrostratigraphic units with contrasting permeability. The tracer plume traveled 6.9 m to well B6, passing through well A1 instrumented with 20 sampling zones over a 5-m interval that spanned the injection interval. Radar tomographic data were collected periodically on cross-sectional and longitudinal planes, two of which passed through well A1 for quantitative calibration of radar …

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A Reinterpretation Of The Small Captorhinid Reptile Captorhinikos Parvus Olson As A New Genus, Reanalysis Of Its Cranial Anatomy, And A Phylogenetic Analysis Of The Basal Reptilian Family Captorhinidae, Gavan Mcbride Albright Jan 2003

A Reinterpretation Of The Small Captorhinid Reptile Captorhinikos Parvus Olson As A New Genus, Reanalysis Of Its Cranial Anatomy, And A Phylogenetic Analysis Of The Basal Reptilian Family Captorhinidae, Gavan Mcbride Albright

Theses Digitization Project

The cranial anatomy of the basal captorhinid reptile Captorhinikos parvus (Reptilia, Captorhinidae), is reinterpreted here based on analysis of a group of new specimens recovered subsequent to its original diagnosis as well as further analysis of the original specimens utilized in E.C. Olson's original characterization of the species. Structural features inconsistent with the generic description suggest the redefinition of C. parvus as a new genus, Rhodotheratus parvus. Analyses of basal members and selected derived members support the characterization of Rhodotheratus as a distinct taxon.

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Could Mammoth Cave Be Reduced To A Single Equation?, Chris Groves, Joe Meiman Jan 2003

Could Mammoth Cave Be Reduced To A Single Equation?, Chris Groves, Joe Meiman

Earth, Environmental, and Atmospheric Sciences Faculty Publications

Since the evolution of any cave system is largely deterministic, in theory the processes responsible for this development could be described mathematically. In a practical sense, we will never have such a model to realistically describe the evolution of the Mammoth Cave System in detail. However, the search itself can provide a framework within which to understand what processes areimportant. This can guide the design of rate process studies that would eventually be coupled to provide a comprehensive understanding of the cave's evolution. Data gaps, as well, are identified during this process. The geometry of a cave system depends on …

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Entropy And Generalized Least Square Methods In Assessment Of The Regional Value Of Streamgages, Momcilo Markus, H. Vernon Knapp, Gary D. Tasker Jan 2003

Entropy And Generalized Least Square Methods In Assessment Of The Regional Value Of Streamgages, Momcilo Markus, H. Vernon Knapp, Gary D. Tasker

United States Geological Survey: Staff Publications

The Illinois State Water Survey performed a study to assess the streamgaging network in the State of Illinois. One of the important aspects of the study was to assess the regional value of each station through an assessment of the information transfer among gaging records for low, average, and high flow conditions. This analysis was performed for the main hydrologic regions in the State, and the stations were initially evaluated using a new approach based on entropy analysis. To determine the regional value of each station within a region, several information parameters, including total net information, were defined based on …

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Changes In The Timing Of High River Flows In New England Over The 20th Century, G. A. Hodgkins, R. W. Dudley, T. G. Huntington Jan 2003

Changes In The Timing Of High River Flows In New England Over The 20th Century, G. A. Hodgkins, R. W. Dudley, T. G. Huntington

United States Geological Survey: Staff Publications

The annual timing of river flows is a good indicator of climate-related changes, or lack of changes, for rivers with long-term data that drain unregulated basins with stable land use. Changes in the timing of annual winter/spring (January 1 to May 31) and fall (October 1 to December 31) center of volume dates were analyzed for 27 rural, unregulated river gaging stations in New England, USA with an average of 68 years of record. The center of volume date is the date by which half of the total volume of water for a given period of time flows past a …

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Selectivities Of Potassium-Calcium And Potassium-Lead Exchange In Two Tropical Soils, Chip Appel, Lena Q. Ma, R. Dean Rhue, William Reve Jan 2003

Selectivities Of Potassium-Calcium And Potassium-Lead Exchange In Two Tropical Soils, Chip Appel, Lena Q. Ma, R. Dean Rhue, William Reve

Earth and Soil Sciences

Measurement of cation selectivity in soils provides important information about the affinity and binding strength of a particular cation on soil surfaces. Gaines-Thomas (KGT) selectivity coefficients were determined for a variety of K/Ca and K/Pb ratios on an Oxisol and Ultisol soil from Puerto Rico. The calculated KGT values indicated a preference for K+ over Ca2+ or Pb2+. The selectivity for Pb2+ was significantly greater than that for Ca2+ due to Pb2+'s larger hydrated charge density relative to that of Ca2+. The patterns of selectivity were independent …

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Soil Survey Of Grand Staircase- Escalante National Monument Area, Parts Of Kane And Garfield Counties, Utah, United States Department Of Agriculture, Natural Resources Conservation Service Jan 2003

Soil Survey Of Grand Staircase- Escalante National Monument Area, Parts Of Kane And Garfield Counties, Utah, United States Department Of Agriculture, Natural Resources Conservation Service

All U.S. Government Documents (Utah Regional Depository)

This soil survey contains information that affects land use planning in this survey area. It contains predictions of soil behavior for selected land uses. The survey also highlights soil limitations, improvements needed to overcome the limitations and the impact of selected land uses on the environment. This soil survey is designed for many different users. Farmers, ranchers, foresters and agronomists can use it to evaluate the potential of the soil and the management needed for maximum food and fiber production. Planners, community officials, engineers, developers, builders and home buyers can use the survey to plan land use, select sites for …

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Lower Gascoyne Land Resources Survey, Peter J. Tille, Henry J. Smolinski, M R. Wells, J A. Bessell-Browne, C D M Keating, Veronica P M Oma, A Mcr Holm Jan 2003

Lower Gascoyne Land Resources Survey, Peter J. Tille, Henry J. Smolinski, M R. Wells, J A. Bessell-Browne, C D M Keating, Veronica P M Oma, A Mcr Holm

Land resources series

No abstract provided.

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Nyabing-Kukerin Area Land Resources Survey, H M. Percy, Dennis Van Gool, Geoff Allan Moore, Noel R. Schoknecht, National Landcare Program (Australia), Natural Heritage Trust (Australia) Jan 2003

Nyabing-Kukerin Area Land Resources Survey, H M. Percy, Dennis Van Gool, Geoff Allan Moore, Noel R. Schoknecht, National Landcare Program (Australia), Natural Heritage Trust (Australia)

Land resources series

This report presents the results from soil and landform mapping at a scale of 1:500,000 in the Kukerin, Lake Grace and Nyabing areas of Western Australia. This land resource information has been collected to help improve the decisions made by planners, researchers and land managers. The information can be used at the regional scale, catchment scale and farm level. By improving knowledge of our land resources, more sustainable land uses can be developed within the region. The soil-landscape map of the area covers approximately 515,000 hectares and is included on the accompanying interactive CD-ROM. The map extends from Lake Grace …

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Red Willow County Test Hole Logs, Duane A. Eversoll Jan 2003

Red Willow County Test Hole Logs, Duane A. Eversoll

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

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Mid-Holocene Climates Of The Americas: A Dynamical Response To Changed Seasonality, S. P. Harrison, J. E. Kutzbach, Z. Liu, P. J. Bartlein, B. Otto-Bliesner, Daniel R. Muhs, I. C. Prentice, R. S. Thompson Jan 2003

Mid-Holocene Climates Of The Americas: A Dynamical Response To Changed Seasonality, S. P. Harrison, J. E. Kutzbach, Z. Liu, P. J. Bartlein, B. Otto-Bliesner, Daniel R. Muhs, I. C. Prentice, R. S. Thompson

United States Geological Survey: Staff Publications

Abstract Simulations of the climatic response to mid- Holocene (6 ka BP) orbital forcing with two coupled ocean–atmosphere models (FOAM and CSM) show enhancement of monsoonal precipitation in parts of the American Southwest, Central America and northernmost South America during Northern Hemisphere summer. The enhanced onshore flow that brings precipitation into Central America is caused by a northward displacement of the inter-tropical convergence zone, driven by cooling of the equatorial and warming of the northern subtropical and mid-latitude ocean. Ocean feedbacks also enhance precipitation over the American Southwest, although the increase in monsoon precipitation there is largely driven by increases …

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Monitoring Trends In Bat Populations Of The United States And Territories: Problems And Prospects, T.J. O'Shea, M. A. Bogan Jan 2003

Monitoring Trends In Bat Populations Of The United States And Territories: Problems And Prospects, T.J. O'Shea, M. A. Bogan

United States Geological Survey: Publications

Bats are ecologically and economically important mammals. The life histories of bats (particularly their low reproductive rates and the need for some species to gather in large aggregations at limited numbers of roosting sites) make their populations vulnerable to declines. Many of the species of bats in the United States (U.S.) and territories are categorized as endangered or threatened, have been candidates for such categories, or are considered species of concern. The importance and vulnerability of bat populations makes monitoring trends in their populations a goal for their future management. However, scientifically rigorous monitoring of bat populations requires well-planned, statistically …

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Geologic Studies Of Mercury By The U.S. Geological Survey Jan 2003

Geologic Studies Of Mercury By The U.S. Geological Survey

United States Geological Survey: Publications

A liquid at room temperature, mercury is a unique metal with unusual properties. Elemental mercury has long been used in thermometers because it responds to changes in temperature. In fact, mercury’s many diverse properties have made it useful for many products. Mercury is a good metallic conductor with a low electrical resistivity; it has been used in electrical products including electrical wiring and switches, fluorescent lamps, mercury batteries, and thermostats (Eisler, 1987). Mercury also is used in navigational instruments to measure changes in temperature and pressure. In the medical field, mercury is used as a component in dental fillings and …

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Review Of Population Viability Analysis, Mark W. Miller Jan 2003

Review Of Population Viability Analysis, Mark W. Miller

United States Geological Survey: Staff Publications

Population viability analysis (PVA) historically has been used to estimate the probability that a population will become extinct within a given time period. More recently, PVA has been used to evaluate alternative management strategies. Some might even say PVA gave rise to conservation biology. Nevertheless, PVA has been heavily criticized. This is the second book to present a synthesis and address those concerns. It does so extremely well.

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Genetic Variation In Black Bears In Arkansas And Louisiana Using Microsatellite Dna Markers, Ildiki Csiki, Cynthia Lam, Audie Key, Erica Coulter, Joseph D. Clark, Richard M. Pace Iii, Kimberley G. Smith, Douglas D. Rhoads Jan 2003

Genetic Variation In Black Bears In Arkansas And Louisiana Using Microsatellite Dna Markers, Ildiki Csiki, Cynthia Lam, Audie Key, Erica Coulter, Joseph D. Clark, Richard M. Pace Iii, Kimberley G. Smith, Douglas D. Rhoads

United States Geological Survey: Staff Publications

In the 1950s and 1960s, translocation projects reintroduced black bears (Ursus americanus) from Minnesota and Manitoba to Arkansas and Louisiana. Today, several geographically disconnected populations exist in Arkansas and Louisiana, but their origins are unclear. Some populations may represent a separate subspecies, U. a. luteolus, which is federally protected. We characterized 5 microsatellite loci in 5 isolated populations in Arkansas and Louisiana and compared them with genotypes from Minnesota. Our data indicate that bears of the Ozark and Ouachita mountains of Arkansas, an inland area of Louisiana, and those of Minnesota are similar in overall genetic diversity …

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Evidence For Disease-Related Amphibian Decline In Colorado, Erin Muths, Paul Stephen Corn, Allan P. Pessier, D. Earl Green Jan 2003

Evidence For Disease-Related Amphibian Decline In Colorado, Erin Muths, Paul Stephen Corn, Allan P. Pessier, D. Earl Green

United States Geological Survey: Staff Publications

The recent discovery of a pathogenic fungus (Batrachochytrium dendrobatidis) associated with declines of frogs in the American and Australian tropics, suggests that at least the proximate cause, may be known for many previously unexplained amphibian declines. We have monitored boreal toads in Colorado since 1991 at four sites using capture–recapture of adults and counts of egg masses to examine the dynamics of this metapopulation. Numbers of male toads declined in 1996 and 1999 with annual survival rate averaging 78% from 1991 to 1994, 45% in 1995 and 3% between 1998 and 1999. Numbers of egg masses also declined. …

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Unprecedented Last-Glacial Mass Accumulation Rates Determined By Luminescence Dating Of Loess From Western Nebraska, Helen M. Roberts, Daniel R. Muhs, Ann G. Wintle, Geoff A. T. Duller, E. Arthur Bettis Iii Jan 2003

Unprecedented Last-Glacial Mass Accumulation Rates Determined By Luminescence Dating Of Loess From Western Nebraska, Helen M. Roberts, Daniel R. Muhs, Ann G. Wintle, Geoff A. T. Duller, E. Arthur Bettis Iii

United States Geological Survey: Staff Publications

A high-resolution chronology for Peoria (last glacial period) Loess from three sites in Nebraska, midcontinental North America, is determined by applying optically stimulated luminescence (OSL) dating to 35–50 µm quartz. At Bignell Hill, Nebraska, an OSL age of 25,000 yr near the contact of Peoria Loess with the underlying Gilman Canyon Formation shows that dust accumulation occurred early during the last glacial maximum (LGM), whereas at Devil’s Den and Eustis, Nebraska, basal OSL ages are significantly younger (18,000 and 21,000 yr, respectively). At all three localities, dust accumulation ended at some time after 14,000 yr ago. Mass accumulation rates …

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Stratigraphy And Palaeoclimatic Significance Of Late Quaternary Loess–Palaeosol Sequences Of The Last Interglacial–Glacial Cycle In Central Alaska, Daniel R. Muhs, Thomas A. Ager, E. Arthur Bettis Iii, John Mcgeehin, Josh M. Been, James E. Begét, Milan J. Pavich, Thomas W. Stafford Jr., De Anne S. P. Stevens Jan 2003

Stratigraphy And Palaeoclimatic Significance Of Late Quaternary Loess–Palaeosol Sequences Of The Last Interglacial–Glacial Cycle In Central Alaska, Daniel R. Muhs, Thomas A. Ager, E. Arthur Bettis Iii, John Mcgeehin, Josh M. Been, James E. Begét, Milan J. Pavich, Thomas W. Stafford Jr., De Anne S. P. Stevens

United States Geological Survey: Staff Publications

Loess is one of the most widespread subaerialdeposits in Alaska and adjacent Yukon Territory and may have a history that goes back 3 Ma. Based on mineralogy and major and trace element chemistry, central Alaskan loess has a composition that is distinctive from other loess bodies of the world, although it is quartz-dominated. Central Alaskan loess was probably derived from a variety of rock types, including granites, metabasalts and schists. Detailed stratigraphic data and pedologic criteria indicate that, contrary to early studies, many palaeosols are present in central Alaskan loess sections. The buried soils indicate that loess sedimentation was episodic, …

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High Precision Earthquake Locations Reveal Seismogenic Structure Beneath Mammoth Mountain, California, Stephanie Prejean, Anna Stork, William Ellsworth, David Hill, Bruce Julian Jan 2003

High Precision Earthquake Locations Reveal Seismogenic Structure Beneath Mammoth Mountain, California, Stephanie Prejean, Anna Stork, William Ellsworth, David Hill, Bruce Julian

United States Geological Survey: Staff Publications

In 1989, an unusual earthquake swarm occurred beneath Mammoth Mountain that was probably associated with magmatic intrusion. To improve our understanding of this swarm, we relocated Mammoth Mountain earthquakes using a double difference algorithm. Relocated hypocenters reveal that most earthquakes occurred on two structures, a near-vertical plane at 7–9 km depth that has been interpreted as an intruding dike, and a circular ring-like structure at ~5.5 km depth, above the northern end of the inferred dike. Earthquakes on this newly discovered ring structure form a conical section that dips outward away from the aseismic interior. Fault-plane solutions indicate that in …

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Imaging The Complexity Of An Active Normal Fault System: The 1997 Colfiorito (Central Italy) Case Study, L. Chiaraluce, W. L. Ellseworth, C. Chiarabba, M. Cocco Jan 2003

Imaging The Complexity Of An Active Normal Fault System: The 1997 Colfiorito (Central Italy) Case Study, L. Chiaraluce, W. L. Ellseworth, C. Chiarabba, M. Cocco

United States Geological Survey: Staff Publications

Six moderate magnitude earthquakes (5 < Mw < 6) ruptured normal fault segments of the southern sector of the North Apennine belt (central Italy) in the 1997 Colfiorito earthquake sequence. We study the progressive activation of adjacent and nearby parallel faults of this complex normal fault system using ~1650 earthquake locations obtained by applying a double-difference location method, using travel time picks and waveform cross-correlation measurements. The lateral extent of the fault segments range from 5 to 10 km and make up a broad, ~45 km long, NW trending fault system. The geometry of each segment is quite simple and consists of planar faults gently dipping toward SW with an average dip of 40 °–45 °. The fault planes are not listric but maintain a constant dip through the entire seismogenic volume, down to 8 km depth. We observe the activation of faults on the hanging wall and the absence of seismicity in the footwall of the structure. The observed fault segmentation appears to be due to the lateral heterogeneity of the upper crust: preexisting thrusts inherited from Neogene’s compressional tectonic intersect the active normal faults and control their maximum length. The stress tensor obtained by inverting the six main shock focal mechanisms of the sequence is in agreement with the tectonic stress active in the inner chain of the Apennine, revealing a clear NE trending extension direction. Aftershock focal mechanisms show a consistent extensional kinematics, 70% of which are mechanically consistent with the main shock stress field.

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Mapping Vegetation In Yellowstone National Park Using Spectral Feature Analysis Of Aviris Data, Raymond F. Kokaly, Don G. Despain, Roger N. Clark, K. Eric Livo Jan 2003

Mapping Vegetation In Yellowstone National Park Using Spectral Feature Analysis Of Aviris Data, Raymond F. Kokaly, Don G. Despain, Roger N. Clark, K. Eric Livo

United States Geological Survey: Staff Publications

Knowledge of the distribution of vegetation on the landscape can be used to investigate ecosystem functioning. The sizes and movements of animal populations can be linked to resources provided by different plant species. This paper demonstrates the application of imaging spectroscopy to the study of vegetation in Yellowstone National Park (Yellowstone) using spectral feature analysis of data from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). AVIRIS data, acquired on August 7, 1996, were calibrated to surface reflectance using a radiative transfer model and field reflectance measurements of a ground calibration site. A spectral library of canopy reflectance signatures was created by …

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Interplay Of Late Cenozoic Siliciclastic Supply And Carbonate Response On The Southeast Florida Platform, Kevin J. Cunningham, Stanley D. Locker, Albert C. Hine, David Bukry, Laura A. Guertin, John A. Barron Jan 2003

Interplay Of Late Cenozoic Siliciclastic Supply And Carbonate Response On The Southeast Florida Platform, Kevin J. Cunningham, Stanley D. Locker, Albert C. Hine, David Bukry, Laura A. Guertin, John A. Barron

United States Geological Survey: Staff Publications

High-resolution seismic-reflection data collected along the length of the Caloosahatchee River in southwestern Florida have been correlated to nannofossil biostratigraphy and strontium-isotope chemostratigraphy at six continuously cored boreholes. These data are interpreted to show a major Late Miocene(?) to Early Pliocene fluvial– deltaic depositional system that prograded southward across the carbonate Florida Platform, interrupting nearly continuous carbonate deposition since early in the Cretaceous. Connection of the platform top to a continental source of siliciclastics and significant paleotopography combined to focus accumulation of an immense supply of siliciclastics on the southeastern part of the Florida Platform. The remarkably thick (> 100 …

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