Open Access. Powered by Scholars. Published by Universities.®

Earth Sciences Commons™

Open Access. Powered by Scholars. Published by Universities.®

Geophysics

Discipline
Institution
Publication Year
Publication
Publication Type

Articles 181 - 210 of 228

Full-Text Articles in Earth Sciences

Geophysical Reconnaissance Of Karst Features Associated With Sinkholes On The Antioch University Campus In Yellow Springs, Ohio: Western Area, Brent Matthew Zerkel Jan 2007

Geophysical Reconnaissance Of Karst Features Associated With Sinkholes On The Antioch University Campus In Yellow Springs, Ohio: Western Area, Brent Matthew Zerkel

Browse all Theses and Dissertations

Antioch University is located in Yellow Springs, OH. This study was conducted on the Antioch University Campus in the commons area and is concentrated on the area west of the easternmost sinkhole. The primary purpose of this study is to locate and identify buried anomalous karst features, such as joints and collapses that may be hazardous to nearby buildings on the Antioch University Campus. The secondary purposes of this study are to identify remaining features in the geophysical data that may be related to manmade structures, and to identify areas for future studies. It is known that an 8-inch steel …

Go to article

Biogeochemistry Of Arsenic And Antimony In The North Pacific Ocean, Gregory A. Cutter, Lynda S. Cutter May 2006

Biogeochemistry Of Arsenic And Antimony In The North Pacific Ocean, Gregory A. Cutter, Lynda S. Cutter

OES Faculty Publications

The biogeochemical cycles of the metalloid elements arsenic and antimony were examined along a 15,000 km surface water transect and at 9 vertical profile stations in the western North Pacific Ocean as part of the 2002 IOC Contaminant Baseline Survey. Results show that the speciation of dissolved arsenic (As III, As V, and methylated As) was subtly controlled by the arsenate (AsV)/phosphate ratio. An additional fraction of presumed organic arsenic previously reported in coastal waters was also present (~15% of the total As) in oceanic surface waters. Dissolved inorganic antimony displayed mildly scavenged behavior that was confirmed by correlations with …

Go to article

Active-Passive Array Surface Wave Inversion And Comparison To Borehole Logs In Southeast Missouri, Alexei A. Malovichko, Neil Lennart Anderson, Dmitriy A. Malovichko, Denis Yu Shylakov, Pavel G. Butirin Sep 2005

Active-Passive Array Surface Wave Inversion And Comparison To Borehole Logs In Southeast Missouri, Alexei A. Malovichko, Neil Lennart Anderson, Dmitriy A. Malovichko, Denis Yu Shylakov, Pavel G. Butirin

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

In May 2002, both active- and passive-source surface wave data were acquired using 4-channel arrays at six selected bridge sites in southeast Missouri. Processing of acquired data (increase of signal-to-noise ratio, estimation of phase velocities) was carried out and dispersion curves of Rayleigh wave phase velocities were constructed. Each fundamental mode dispersion curve was then inverted by linearised optimization to a layered shear-wave velocity profile to depths of up to 60 m. The estimated shear-wave velocity profiles were compared to other geotechnical data that had been previously acquired at each test site for the Missouri Department of Transportation (MoDOT) including …

Go to article

Hydrogeophysical Investigation At Luxor, Southern Egypt, Ahmed Ismail, Neil Lennart Anderson, J. David Rogers Mar 2005

Hydrogeophysical Investigation At Luxor, Southern Egypt, Ahmed Ismail, Neil Lennart Anderson, J. David Rogers

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Over the past 35 years, the exposed stone foundations of the ancient Egyptian monuments at Luxor have deteriorated at an alarmingly accelerated rate. Accelerated deterioration is attributable to three principal factors: 1) excavation and exposure of foundation stone; 2) construction of the Aswan High Dam; and 3) changes in the regional groundwater regime. In an effort to better elucidate the hydrostratigraphy in the Luxor study area that extends from the River Nile to the boundaries of the Nile Valley and covers about 70 km2, a geophysical/hydrological investigation was conducted. Forty Schlumberger vertical electrical soundings (VES), two approximately 6 …

Go to article

Extent And Duration Of The 2003 Cascadia Slow Earthquake, Walter Szeliga, Timothy I. Melbourne, M. Meghan Miller, Victor Marcelo Santillan Feb 2005

Extent And Duration Of The 2003 Cascadia Slow Earthquake, Walter Szeliga, Timothy I. Melbourne, M. Meghan Miller, Victor Marcelo Santillan

Faculty Scholarship for the Cascadia Hazards Institute

Inversion of continuous GPS measurements from the Pacific Northwest show the 2003 Cascadia slow earthquake to be among the largest of ten transients recognized here. Twelve stations bracketing slow slip indicate transient slip propagated bi-directionally from initiation in the southern Puget basin, reaching 300 km along-strike over a period of seven weeks. This event produced, for the first time, resolvable vertical subsidence, and horizontal displacement reaching six mm in southern Washington State. Inverted for non-negative thrust slip, a maximum of 3.8 cm of slip is inferred, centered at 28 km depth near the sharp arch in the subducting Juan de …

Go to article

New Standards For Reducing Gravity Data: The North American Gravity Database, William J. Hinze, Carlos Aiken, John Brozena, Bernard Coakley, David Dater, Guy Flanagan, Rene Forsberg, Thomas Hildenbrand, G. Randy Keller, James N. Kellogg, Robert Kucks, Xiong Li, Andre Mainville, Robert Morin, Mark Pilkington, Donald Plouff, Dhananjay Ravat, Daniel Roman, Jamie Urrutia-Fucugauchi, Marc Veronneau, Michael Webring, Daniel Winester Jan 2005

New Standards For Reducing Gravity Data: The North American Gravity Database, William J. Hinze, Carlos Aiken, John Brozena, Bernard Coakley, David Dater, Guy Flanagan, Rene Forsberg, Thomas Hildenbrand, G. Randy Keller, James N. Kellogg, Robert Kucks, Xiong Li, Andre Mainville, Robert Morin, Mark Pilkington, Donald Plouff, Dhananjay Ravat, Daniel Roman, Jamie Urrutia-Fucugauchi, Marc Veronneau, Michael Webring, Daniel Winester

Faculty Publications

The North American gravity database as well as databases from Canada, Mexico, and the United States are being revised to improve their coverage, versatility, and accuracy. An important part of this effort is revising procedures for calculating gravity anomalies, taking into account our enhanced computational power, improved terrain databases and datums, and increased interest in more accurately defining long-wavelength anomaly components. Users of the databases may note minor differences between previous and revised database values as a result of these procedures. Generally, the differences do not impact the interpretation of local anomalies but do improve regional anomaly studies. The most …

Go to article

Field Evidence For Geophysical Detection Of Subsurface Zones Of Enhanced Microbial Activity, Eliot A. Atekwana, Estella A. Atekwana, Franklyn D. Legall, R. V. Krishnamurthy Dec 2004

Field Evidence For Geophysical Detection Of Subsurface Zones Of Enhanced Microbial Activity, Eliot A. Atekwana, Estella A. Atekwana, Franklyn D. Legall, R. V. Krishnamurthy

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Geochemical data from closely spaced vertical intervals in a hydrocarbon-impacted aquifer were used to assess the relationship between bulk conductivity and zones of enhanced microbial activity. The bulk conductivity was measured using in situ vertical resistivity probes. Microbial activity was verified using terminal electron acceptors (nitrate, sulfate, iron, and manganese), dissolved inorganic carbon (DIC), and major ion chemistry. Peaks in bulk conductivity in the aquifer overlapped with zones where nitrates and sulfates were depleted, total petroleum hydrocarbon, iron, manganese, dissolved ions, and DIC were elevated, suggesting a link between higher electrical conductivity and zones of enhanced microbial activity stimulated by …

Go to article

Significant Crustal Thinning Beneath The Baikal Rift Zone: New Constraints From Receiver Function Analysis, Stephen S. Gao, Kelly H. Liu, Chizheng Chen Oct 2004

Significant Crustal Thinning Beneath The Baikal Rift Zone: New Constraints From Receiver Function Analysis, Stephen S. Gao, Kelly H. Liu, Chizheng Chen

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Thinning of the crust of more than 10 km is a major feature of typical continental rifts such as the East African (EAR) and Rio Grande (RGR) rifts. However, numerous previous studies across the Baikal rift zone (BRZ), which has similar surface expressions and tectonic history, and more active seismicity relative to EAR and RGR, have resulted in contradicting amount of thinning, ranging from almost none to more than 10 km. We measure crustal thickness by stacking teleseismic receiver functions beneath 51 sites on the southern and central parts of the BRZ and adjacent Siberian Platform and Sayan-Baikal-Mongolian Foldbelt. Our …

Go to article

Southern Cascadia Episodic Slow Earthquakes, Walter Szeliga, Timothy I. Melbourne, M. Meghan Miller, Marcelo Santillan Aug 2004

Southern Cascadia Episodic Slow Earthquakes, Walter Szeliga, Timothy I. Melbourne, M. Meghan Miller, Marcelo Santillan

Faculty Scholarship for the Cascadia Hazards Institute

Continuous GPS and seismic data from northern California show that slow earthquakes periodically rupture the Gorda-North America plate interface within southern Cascadia. On average, these creep events have occurred every 10.9±1.2 months since at least 1998. Appearing as week-long GPS extensional transients that reverse secular forearc contraction, the data show a recurrence interval 22% shorter than slow events recognized to the north. Seismic tremor here accompanies the GPS reversals, correlated across as many as 5 northern California seismometers. Tremor occurs sporadically throughout the year, but increases in duration and intensity by a factor of about 10 simultaneous with the GPS …

Go to article

Effects Of Microbial Processes On Electrolytic And Interfacial Electrical Properties Of Unconsolidated Sediments, Gamal Z. Abdal Aal, Estella A. Atekwana, Lee D. Slater, Eliot A. Atekwana Jun 2004

Effects Of Microbial Processes On Electrolytic And Interfacial Electrical Properties Of Unconsolidated Sediments, Gamal Z. Abdal Aal, Estella A. Atekwana, Lee D. Slater, Eliot A. Atekwana

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The effect of microbial processes on electrical properties of unconsolidated sediments was investigated in a laboratory experiment consisting of biotic and abiotic sand columns. The biotic column (nutrient, diesel and bacteria) showed (a) temporal increase in the real, imaginary, and surface conductivity, and (b) temporal decrease in the formation factor. The abiotic columns (nutrient; and nutrient and diesel) showed no significant changes. Increase in microbial population numbers, decrease in organic carbon source, nitrate, and sulfate and increase in dissolved inorganic carbon and fluid conductivity were indicative of microbial activity in the biotic column. We also measure relative increase in the …

Go to article

Field-Scale Estimation Of Volumetric Water Content Using Ground-Penetrating Radar Ground Wave Techniques, Katherine R. Grote, Susan Sharpless Hubbard, Yoram N. Rubin Nov 2003

Field-Scale Estimation Of Volumetric Water Content Using Ground-Penetrating Radar Ground Wave Techniques, Katherine R. Grote, Susan Sharpless Hubbard, Yoram N. Rubin

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Ground-penetrating radar (GPR) ground wave techniques were applied to estimate soil water content in the uppermost ∼10 cm of a 3 acre California vineyard several times over 1 year. We collected densely spaced GPR travel time measurements using 900 and 450 MHz antennas and analyzed these data to estimate water content. The spatial distribution of water content across the vineyard did not change significantly with time, although the absolute water content values varied seasonally and with irrigation. The GPR estimates of water content were compared to gravimetric water content, time domain reflectometry, and soil texture measurements. The comparisons of GPR-derived …

Go to article

Investigating The Geoelectrical Response Of Hydrocarbon Contamination Undergoing Biodegradation, D. Dale Werkema, Estella A. Atekwana, Anthony L. Endres, William August Sauck, Daniel P. Cassidy Jun 2003

Investigating The Geoelectrical Response Of Hydrocarbon Contamination Undergoing Biodegradation, D. Dale Werkema, Estella A. Atekwana, Anthony L. Endres, William August Sauck, Daniel P. Cassidy

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

A newly proposed geoelectrical model for hydrocarbon contaminated sites predicts high conductivities coincident with the contaminated zone as opposed to the traditionally accepted low conductivity. The model attributes the high conductivities to mineral weathering resulting from byproducts of microbial redox processes. To evaluate this conductive model, in situ vertical conductivity measurements were acquired from a light non-aqueous phase liquid (LNAPL) contaminated site. The results showed high conductivities coincident with the zone of contamination and within the smear zone influenced by seasonal water table fluctuations. We infer this zone as an active zone of biodegradation and suggest significant microbial degradation under …

Go to article

Understanding Wavelet Analysis And Filters For Engineering Applications, Chethan Bangalore Parameswariah Apr 2003

Understanding Wavelet Analysis And Filters For Engineering Applications, Chethan Bangalore Parameswariah

Doctoral Dissertations

Wavelets are signal-processing tools that have been of interest due to their characteristics and properties. Clear understanding of wavelets and their properties are a key to successful applications. Many theoretical and application-oriented papers have been written. Yet the choice of a right wavelet for a given application is an ongoing quest that has not been satisfactorily answered. This research has successfully identified certain issues, and an effort has been made to provide an understanding of wavelets by studying the wavelet filters in terms of their pole-zero and magnitude-phase characteristics. The magnitude characteristics of these filters have flat responses in both …

Go to article

Temporal Variation Of Seismic B-Values Beneath Northeastern Japan Island Arc, Aimin Cao, Stephen S. Gao May 2002

Temporal Variation Of Seismic B-Values Beneath Northeastern Japan Island Arc, Aimin Cao, Stephen S. Gao

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Analysis of a high quality seismic catalog reveals that the average of seismic b-values in the crust beneath most part of northeastern Japan island arc decreased from 0.86 between 1984 and 1990, to 0.73 between 1991 and 1995. The two areas with the largest decrease are found to be in the same areas where the coupling between the North American and the Pacific plates is the highest, as suggested by a recent geodetic study. In the same time period, the annual seismic moment release increased by 10 times. In addition, there seems to be a corresponding increase in volcanic activities …

Go to article

Mantle Discontinuities Beneath Southern Africa, Stephen S. Gao, Paul G. Silver, Kelly H. Liu, Kaapvaal Seismic Group May 2002

Mantle Discontinuities Beneath Southern Africa, Stephen S. Gao, Paul G. Silver, Kelly H. Liu, Kaapvaal Seismic Group

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Seismic velocity discontinuities within the top 1000 km of the Earth beneath southern Africa are imaged by stacking about 1300 source-normalized broadband seismograms recorded by the Southern African Seismic Experiment. The Moho, 410, and 660 kilometer discontinuities are clearly detected. The mean mantle transition zone thickness is 245 km, essentially the same as the global average, suggesting that the transition zone is not anomalously warm. Thus, the lower-mantle 'African Superplume' beneath our study area has no discernible effect on transition zone temperature and is consequently confined to the lower mantle. Variations in transition zone thickness appear to be related to …

Go to article

Mantle Control Of Plate Boundary Deformation, Timothy I. Melbourne, Don Helmberger Oct 2001

Mantle Control Of Plate Boundary Deformation, Timothy I. Melbourne, Don Helmberger

Faculty Scholarship for the Cascadia Hazards Institute

The seismic wavefield propagating along the recently instrumented Pacific-North American plate boundary (California) displays remarkable variation, with regional shear waves arriving at coastal stations up to 20 seconds earlier than equidistant stations in eastern California. Broadband modeling of this data reveals that coastal paths sample fast upper mantle typical of Miocene-aged ocean plate (> 50 Km thickness). Inland paths sample slower uppermost mantle, with the seismic lithosphere, or lid, measuring less than 5 Km thick, characteristic of the Basin and Range extensional province. The boundary in the uppermost mantle between these provinces is sharp, expressing the juxtaposition of the stronger …

Go to article

Present Day Kinematics Of The Eastern California Shear Zone From A Geodetically Constrained Block Model, S. C. Mcclusky, S. C. Bjornstad, B. H. Hager, R. W. King, B. J. Meade, M. Meghan Miller, F. C. Monastero, B. J. Souter Sep 2001

Present Day Kinematics Of The Eastern California Shear Zone From A Geodetically Constrained Block Model, S. C. Mcclusky, S. C. Bjornstad, B. H. Hager, R. W. King, B. J. Meade, M. Meghan Miller, F. C. Monastero, B. J. Souter

All Faculty Scholarship for the College of the Sciences

We use Global Positioning System (GPS) data from 1993–2000 to determine horizontal velocities of 65 stations in eastern California and western Nevada between 35° and 37° N. We relate the geodetic velocities to fault slip rates using a block model that enforces path integral constraints over geologic and geodetic time scales and that includes the effects of elastic strain accumulation on faults locked to a depth of 15 km. The velocity of the Sierra Nevada block with respect to Nevada is 11.1±0.3 mm/yr, with slip partitioned across the Death Valley, (2.8±0.5 mm/yr), Panamint Valley (2.5±0.8 mm/yr), and Airport Lake/Owens Valley …

Go to article

Refined Kinematics Of The Eastern California Shear Zone From Gps Observations, 1993-1998, M. Meghan Miller, Timothy H. Dixon, Roy K. Dokka Feb 2001

Refined Kinematics Of The Eastern California Shear Zone From Gps Observations, 1993-1998, M. Meghan Miller, Timothy H. Dixon, Roy K. Dokka

All Faculty Scholarship for the College of the Sciences

Global Positioning System (GPS) results from networks spanning the Eastern California shear zone and adjacent Sierra Nevada block, occupied annually between 1993 and 1998, constrain plate margin kinematics. We use an elastic block model to relate GPS station velocities to long‐term fault slip rate estimates. The model accounts for elastic strain accumulation on the San Andreas fault, as well as faults of the Eastern California shear zone. South of the Garlock fault, 14 mm/yr of dextral shear is distributed across the Eastern California shear zone. Some of this slip penetrates eastward into the Basin and Range, and a collective budget …

Go to article

Basaltic Lava Domes, Lava Lakes, And Volcanic Segmentation On The Southern East Pacific Rise, Scott M. White, Ken C. Macdonald, Rachel M. Haymon Oct 2000

Basaltic Lava Domes, Lava Lakes, And Volcanic Segmentation On The Southern East Pacific Rise, Scott M. White, Ken C. Macdonald, Rachel M. Haymon

Faculty Publications

Meter-scale DSL-120 sonar mapping and coregistered Argo II photographic observations reveal changes in eruptive style that closely follow the third-order structural segmentation of the ridge axis on the southern East Pacific Rise, 17o11'-18o37'S. Near segment ends we observe abundant basaltic lava domes which average 20 rn in height and 200 rn in basal diameter and have pillow lava as the dominant lava morphology. The ubiquity of pillow lava suggests low effusion rate eruptions. The abundance of lava domes suggests that the fissure eruptions were of sufficient duration to focus and produce a line of volcanic edifices. …

Go to article

Chemical Signals From Submarine Fluid Advection Onto The Continental Shelf, W. S. Moore, Timothy J. Shaw Sep 1998

Chemical Signals From Submarine Fluid Advection Onto The Continental Shelf, W. S. Moore, Timothy J. Shaw

Faculty Publications

No abstract provided.

Go to article

The Geodetic Signature Of The M8.0 Oct. 9, 1995, Jalisco Subduction Earthquake, Timothy I. Melbourne, I. Carmichael, C. Demets, K. Hudnut, O. Sanchez, J. Stock, G. Suarez, F. Webb Mar 1997

The Geodetic Signature Of The M8.0 Oct. 9, 1995, Jalisco Subduction Earthquake, Timothy I. Melbourne, I. Carmichael, C. Demets, K. Hudnut, O. Sanchez, J. Stock, G. Suarez, F. Webb

Faculty Scholarship for the Cascadia Hazards Institute

The October, 1995 Mw 8.0 Jalisco subduction earthquake has provided a thorough geodetic observation of the coseismic subduction process. An 11 station regional GPS network located directly onshore of the rupture demonstrates consistent vertical subsidence verified by tide gauge data and southwest-directed extension, with measured displacements reaching 1 meter. Unusually shallow and non-uniform faulting is required to explain the displacements. We determine that up to 5 meters of slip occurred within the upper 15 km of the thrust fault zone and 2 meters possibly as shallow as 8 km, and that slip was likely distributed in two main patches. The …

Go to article

Vertical Resolution Of A Seismic Survey In Stratigraphic Sequences Less Than 100 M Deep In Southeastern Kansas, Richard Daniel J. Miller, Neil Lennart Anderson, Howard Randall Feldman, Evan K. Franseen Apr 1995

Vertical Resolution Of A Seismic Survey In Stratigraphic Sequences Less Than 100 M Deep In Southeastern Kansas, Richard Daniel J. Miller, Neil Lennart Anderson, Howard Randall Feldman, Evan K. Franseen

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

A 400-m long, 12-fold high-resolution common depth point (CDP) reflection seismic profile was acquired across shallow converging Pennsylvanian strata in the Independence area of southeastern Kansas. One of the principal objectives was to determine practical vertical resolution limits in an excellent shallow seismic-data area with borehole control. The dominant frequency of the CDP stacked data is in excess of 150 Hz based on peak-to-peak measurements. Interference phenomena observed on stacked seismic data incorporated with models derived from log and drill-hole information suggest a practical vertical resolution limit of about 7 m, or one-third of the dominant wavelength. The data suggest …

Go to article

Plate Motions In The North Andean Region, Jeffrey T. Freymueller, James N. Kellogg, Victor Vega Dec 1993

Plate Motions In The North Andean Region, Jeffrey T. Freymueller, James N. Kellogg, Victor Vega

Faculty Publications

Repeated geodetic measurements with the Global Positioning System (GPS) provide direct measurements of displacements due to plate motions and active crustal deformation in Central America and northern South America, an area of complex interaction of the Nazca, Cocos, Caribbean and South American plates. The displacement rates for the period 1988-1991, obtained from the results of the first three Central And South America (CASA) GPS campaigns, are in general agreement with the predictions of the NUVEL-1 plate motion model, but there are differences in detail between the observations and the model. The Nazca-North Andes convergence rate vector measured by GPS is …

Go to article

Westhazel General Petroleums Pool: Case History Of A Salt- Dissolution Trap In West-Central Saskatchewan, Canada, Neil Lennart Anderson, Dale A. Cederwall Jun 1993

Westhazel General Petroleums Pool: Case History Of A Salt- Dissolution Trap In West-Central Saskatchewan, Canada, Neil Lennart Anderson, Dale A. Cederwall

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The Westhazel General Petroleums (GP) Pool of west-central Saskatchewan, Canada, produces from the GP member of the Lower Cretaceous Mannville Group. This reservoir is structurally closed across the updip, eastern dissolutional edge of the underlying Middle Devonian rock salt of the Leofnard Member, Prairie Formation. The leaching of these salts occurred in post-Mannville time in the Westhazel area and caused the regional southwest dip of the General Petroleums member to be locally reversed.The Westhazel GP Pool, from a geophysical perspective, is characteristic of many of the shallow Lower Cretaceous pools situated along the dissolutional edge of the Prairie salt. The …

Go to article

Basement Structure Of The Northern Ontong Java Plateau, Rick A. Hagen, Larry A. Mayer, David Mosher, Loren W. Kroenke, Tom H. Shipley, Edward L. Winterer Jan 1993

Basement Structure Of The Northern Ontong Java Plateau, Rick A. Hagen, Larry A. Mayer, David Mosher, Loren W. Kroenke, Tom H. Shipley, Edward L. Winterer

Affiliate Scholarship

Site surveys conducted in conjunction with Leg 130 on the Ontong Java Plateau reveal a strong seismic reflector at 0.8 to 1.0 s below the seafloor that drilling at Sites 803 and 807 confirmed is Cretaceous basalt. This reflector is generally smooth, except for the northeastern margin of the plateau, where it forms a series of small, irregularly shaped depressions. Correlatable reflectors present at the bottom of the depressions are also present on the adjacent highs, suggesting that these depressions are original volcanic topography. A strong sub-basalt reflector occurs on many seismic profiles on the northeastern portion of the plateau. …

Go to article

Manual Of Field Techniques In Hydrology, Department Of Agriculture, Western Australia. Division Of Resource Management Jan 1991

Manual Of Field Techniques In Hydrology, Department Of Agriculture, Western Australia. Division Of Resource Management

Agriculture reports

No abstract provided.

Go to article

The Extended Tracking Network And Indications Of Baseline Precision And Accuracy In The North Andes, Jeffrey T. Freymueller, James N. Kellogg Mar 1990

The Extended Tracking Network And Indications Of Baseline Precision And Accuracy In The North Andes, Jeffrey T. Freymueller, James N. Kellogg

Faculty Publications

The CASA UNO Global Positioning System (GPS) experiment (January-February 1988) included an extended tracking network which covered three continents in addition to the network of scientific interest in Central and South America. The repeatability of long baselines (400-1000 km) in South America is improved by up to a factor of two in the horizontal vector baseline components by using tracking stations in the Pacific and Europe to supplement stations in North America. In every case but one, the differences between the mean solutions obtained using different tracking networks was equal to or smaller than day-to-day rms repeatabilities for the same …

Go to article

Structural, Remote Sensing And Multivariate Correlation Methods As Aids To Mineral Exploration, Central Ireland, D.W. Coller, M.F. Critchley, J.M. Dolan, Ciaran Mcdonnell, C.J. Murphy, W.E.A. Phillips, D.J. Sanderson Dec 1986

Structural, Remote Sensing And Multivariate Correlation Methods As Aids To Mineral Exploration, Central Ireland, D.W. Coller, M.F. Critchley, J.M. Dolan, Ciaran Mcdonnell, C.J. Murphy, W.E.A. Phillips, D.J. Sanderson

Books/Book chapters

This work discusses structural, remote sensing and multivariate correlation methods as aids to mineral exploration in West Central Ireland. The work was performed as part of the EU-funded CREST project.

Go to article

Hydrothermal Alteration At The Roosevelt Hot Springs Thermal Area, Utah: Petrographic Characterization Of The Alteration To 2 Kilometers Depth, J. M. Ballantyne, W. T. Parry Apr 1978

Hydrothermal Alteration At The Roosevelt Hot Springs Thermal Area, Utah: Petrographic Characterization Of The Alteration To 2 Kilometers Depth, J. M. Ballantyne, W. T. Parry

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

Hydrothermal alteration in drill cuttings from Thermal Power drillhole 14-2, Roosevelt Hot Springs Thermal area, has been studied petrographically. The hole is sited in alluvium approximately 1.6 km southeast of the old Resort and was rotary drilled to a depth of 1866.0 m. The exact hole location is 2310 FNL, 350 FWL, Sec. 2, Twp 27S, Rge 9W, elevation 1908.5 m. Core was extracted from 792.5 to 795.5 m. Thin sections were made from samples 15.2 m intervals of drill cuttings collected at 1.5 or 3.0 m intervals during drilling. Thin sections were made of 1.5 or 3.0 m intervals …

Go to article

Quaternary Rhyolite From The Mineral Mountains, Utah, U.S.A., S. H. Evans, Jr., W. P. Nash, University Of Utah, Department Of Geology And Geophysics Jan 1978

Quaternary Rhyolite From The Mineral Mountains, Utah, U.S.A., S. H. Evans, Jr., W. P. Nash, University Of Utah, Department Of Geology And Geophysics

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

A suite of silicic volcanic rocks is associated with the Roosevelt Hot Springs geothermal area in southwestern Utah. The volcanic sequence includes Tertiary rhyolite 8 m.y. old and obsidian, ash and rhyolite of Quaternary age. The Quaternary lavas are characterized by high silica content (76.5% SiO2) and total alkalies in excess of 9 percent. Obsidians commonly contain greater amounts of flourine than water. Two older flows (0.8 m.y.) can be distinguished from younger dome and pyroclastic material (approximately 0.5 m.y.) by subtle differences in their chemistry. The mineralogy of the rhyolites consists of alkali feldspar, plagioclase, and small amounts of …

Go to article

First Prev Next Last