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Articles 31 - 60 of 60
Full-Text Articles in Geophysics and Seismology
Constraining Boundaries And Extent Of The Charleston Uplift, Northeast New Madrid Seismic Zone, Using Shallow Seismic Reflection Methods, Clara Rose Rucker
Constraining Boundaries And Extent Of The Charleston Uplift, Northeast New Madrid Seismic Zone, Using Shallow Seismic Reflection Methods, Clara Rose Rucker
Theses and Dissertations--Earth and Environmental Sciences
A recently identified 30 km by 7.2 km subsurface stratigraphic uplift, called the Charleston uplift, exhibits 36 m offset of Paleogene-Quaternary unconformity based on shallow borehole data. Two seismic soundings demonstrated relief in Paleozoic and Cretaceous reflectors across the northern boundary of the uplift, suggesting a structural origin rather than an erosional origin. This study collected and analyzed 18 additional shallow seismic soundings to confirm Paleozoic and Cretaceous offset across the boundaries of the uplift, to better constrain the surface trace of the uplift, and to examine potential extension into western Kentucky. One ground penetrating radar profile was taken in …
Initial Microseismic Recordings At The Onset Of Unconventional Hydrocarbon Development In The Rome Trough, Eastern Kentucky, Andrew Holcomb
Initial Microseismic Recordings At The Onset Of Unconventional Hydrocarbon Development In The Rome Trough, Eastern Kentucky, Andrew Holcomb
Theses and Dissertations--Earth and Environmental Sciences
The Cambrian Rogersville Shale is a part of a hydrocarbon system in the Rome Trough of eastern Kentucky and West Virginia that can only be produced unconventionally. In Kentucky, the Rogersville Shale ranges in depth from ~1,800 to ~3,700 m below the surface with the crystalline basement ~1,000 m lower than the formation’s base. Baseline Rome Trough microseismicity data were collected, focusing on wastewater injection wells and recently completed and planned unconventional hydrocarbon test wells in the Rogersville Shale, using thirteen broadband seismic stations installed between June, 2015 and June, 2016 and existing University of Kentucky and central and eastern …
Potential Field Modeling Across The Neodymium Line Defining The Paleoproterozoic-Mesoproterozoic Boundary Of The Southeastern Margin Of Laurentia, Rachel Lauren Durham
Potential Field Modeling Across The Neodymium Line Defining The Paleoproterozoic-Mesoproterozoic Boundary Of The Southeastern Margin Of Laurentia, Rachel Lauren Durham
Theses and Dissertations--Earth and Environmental Sciences
A zone of high magnetization along the SE margin of Paleoproterozoic Laurentia in the United States is indicated by magnetic anomaly data. The SE edge corresponds to the geochemical Neodymium mantle derivation model age (TDM) boundary and the entire anomaly overlies the Paleoproterozoic Mazatzal Province. Two-dimensional gravity and magnetic models across the Nd boundary are created with Moho constrained from receiver functions with gravity, sedimentary thickness and the base of the crustal magnetization. Upper crustal magnetization does not show strong variation across this boundary and much of the strong magnetization appears to lie in the middle crust. Using …
Earthquake Hazard Mitigation In The New Madrid Seismic Zone: Science And Public Policy, Alice M. Orton, Zhenming Wang, Lanmin Wang, Edward W. Woolery
Earthquake Hazard Mitigation In The New Madrid Seismic Zone: Science And Public Policy, Alice M. Orton, Zhenming Wang, Lanmin Wang, Edward W. Woolery
Report of Investigations--KGS
In the central United States, earthquake sources that are not well defined, long earthquake recurrence intervals, and uncertain ground-motion attenuation models have contributed to an overstatement of seismic hazard for the New Madrid Seismic Zone on the national seismic hazard maps published by the U.S. Geological Survey. A series of informal interviews in western Kentucky with local businesspersons, public officials, and other professionals in occupations associated with seismic-hazard mitigation discussed seismic-mitigation policies in relation to depressed local economy. Scientific and relative economic analysis was then performed using scenario earthquake models developed with the Federal Emergency management Agency's Hazus-MH software. The …
Site Characteristics, Instrumentation, And Recordings Of The Central United States Seismic Observatory, Edward W. Woolery, Zhenming Wang, N. Seth Carpenter
Site Characteristics, Instrumentation, And Recordings Of The Central United States Seismic Observatory, Edward W. Woolery, Zhenming Wang, N. Seth Carpenter
Report of Investigations--KGS
The Central United States Seismic Observatory is a vertical seismic array in southwestern Kentucky within the New Madrid Seismic Zone. It is intended to record the effects of local geology, including thick sediment overburden, on seismic-wave propagation, particularly strong ground motion. The three-borehole array is composed of seismic sensors placed on the surface, in the bedrock, and at various depths within the 585-m-thick sediment overburden. The array's deep borehole also provides a unique opportunity to describe the geology and geophysically measure the complete Late Cretaceous through Quaternary stratigraphy in the northern Mississippi Embayment.
Based on the surface and borehole geophysical …
Use Of Laboratory Geophysical And Geotechnical Investigation Methods To Characterize Gypsum Rich Soils, Raghava A. Bhamidipati
Use Of Laboratory Geophysical And Geotechnical Investigation Methods To Characterize Gypsum Rich Soils, Raghava A. Bhamidipati
Theses and Dissertations--Civil Engineering
Gypsum rich soils are found in many parts of the world, particularly in arid and semi-arid regions. Most gypsum occurs in the form of evaporites, which are minerals that precipitate out of water due to a high rate of evaporation and a high mineral concentration. Gypsum rich soils make good foundation material under dry conditions but pose major engineering hazards when exposed to water. Gypsum acts as a weak cementing material and has a moderate solubility of about 2.5 g/liter. The dissolution of gypsum causes the soils to undergo unpredictable collapse settlement leading to severe structural damages. The damages incur …
Integrated Geophysical Methods In Investigation Of Claiborne Aquifer Hydrostratigraphy, Jackson Purchase, Kentucky, Marie Cooper
Integrated Geophysical Methods In Investigation Of Claiborne Aquifer Hydrostratigraphy, Jackson Purchase, Kentucky, Marie Cooper
Theses and Dissertations--Earth and Environmental Sciences
Increased groundwater withdrawals associated with agricultural irrigation in the Jackson Purchase have prompted questions related to groundwater availability and sustainability. Key factors in addressing these questions are understanding the extent and variation in thickness of the local hydrostratigraphic system, which is the upper part of the Mississippi Embayment aquifer system. Correlations of 70 gamma-ray well logs, and 49 resistivity logs were made across parts of the Jackson Purchase in Fulton and Hickman Counties in order to delineate the upper Claiborne aquifer and middle Claiborne confining unit. Commercial software (i.e. Petra 3.8.3) was used to generate cross sections, structure and isopach …
Development Of A Semi-Automated Methodology For Discriminating Between Natural And Manmade Seismic Events Using The Oiink Seismic Array, Paul Rodriguez Asihama
Development Of A Semi-Automated Methodology For Discriminating Between Natural And Manmade Seismic Events Using The Oiink Seismic Array, Paul Rodriguez Asihama
Theses and Dissertations--Earth and Environmental Sciences
Broadband waveforms from the Ozark, Indiana, Illinois, Kentucky temporary seismic array OIINK, a Flexible Array in the EarthScope project, were used to develop routines to identify and remove mine blast events from a database of local events and preserve the infrequent, small, natural earthquakes. The approach taken was to first create a database of all seismic events that were detected by the OIINK Seismic Array. False-detections, events detected from outside of the project area (approx. 302 thousand square km), and known (i.e. cataloged) local earthquake were also removed. The remaining in the database were local unknown events. During the Phase …
Inverse Modelling Of The Reversely Magnetized, Shallow Plumbing System Hosting Oil Reservoirs Of The Auca Mahuida Volcano (Payeina Retroarc, Neuquén Basin, Argentina), John Paine, Riccardo De Ritis, Guido Ventura, Mariana Longo, Dhananjay Ravat, Fabio Speranza, Massimo Chiappini
Inverse Modelling Of The Reversely Magnetized, Shallow Plumbing System Hosting Oil Reservoirs Of The Auca Mahuida Volcano (Payeina Retroarc, Neuquén Basin, Argentina), John Paine, Riccardo De Ritis, Guido Ventura, Mariana Longo, Dhananjay Ravat, Fabio Speranza, Massimo Chiappini
Earth and Environmental Sciences Faculty Publications
The Auca Mahuida volcano (2.03–0.88 Ma) located east of the Andean thrust front in the Neuquén basin (Argentina) hosts an oil system of thermogenic origin and is affected by the NW–SE striking-faults. Intrusive bodies and the underlying Jurassic sediments constitute the reservoir rocks. Aeromagnetic data collected in the Auca Mahuida area detected multiple dipolar magnetic anomalies, many of which have reverse polarity. Palaeomagnetic measurements on rock samples collected in the field together with available age determinations indicate that the reversely magnetized sources were mainly emplaced during the Matuyama reverse polarity chron while the normal polarity sources were emplaced during the …
Detection Of Small-Scale Rockfall Incidents Using Their Seismic Signature, Achilleas Tripolitsiotis, Antonis Daskalakis, Stelios Mertikas, Dionysios Hristopulos, Zacharias Agioutantis, Panagiotis Partsinevelos
Detection Of Small-Scale Rockfall Incidents Using Their Seismic Signature, Achilleas Tripolitsiotis, Antonis Daskalakis, Stelios Mertikas, Dionysios Hristopulos, Zacharias Agioutantis, Panagiotis Partsinevelos
Mining Engineering Faculty Publications
Several algorithms have been effectively used to identify the seismic signature of rockfall incidents, which constitute a significant threat for human lives and infrastructure especially when occurring along transportation networks. These algorithms have been mostly evaluated using data from large scale rockfall events that release a large amount of energy. However, low-energy rockfall events (< 100 Joules) triggered by small-sized individual rocks falling from small heights can be severely destructive. In this study, a three-parameter algorithm has been developed to identify low-energy rockfall events. An experimental setup was implemented to 1) validate the results obtained by this algorithm against visual inspection of seismic signals records, 2) define the optimal algorithm parameterization to minimize false alarms, and 3) investigate whether tri-axial vibration monitoring can be replaced by a uniaxial device in order to reduce the installation cost of a real-time rockfall monitoring system. It was found that the success rate of the proposed algorithm exceeds 80% independently of the parameters used, while event identification at a maximum distance with minimal false alarms was achieved when using mean ± 3σ as the threshold criterion and 6 ms and 4 ms as the trigger and event window parameters respectively. Finally, it was found that for the specific experimental setup, a uniaxial device could be used for rockfall event identification.
Commercialization Of A Small, Lightweight, Low-Cost Seismic Borehole Receiver, Rachel Adams
Commercialization Of A Small, Lightweight, Low-Cost Seismic Borehole Receiver, Rachel Adams
Theses and Dissertations--Civil Engineering
Herein, conceptualization of a recently patented seismic borehole receiver and its components is developed for commercialization. The device is significantly cheaper, lighter, and smaller than existing technologies on the market. Additionally, it has the potential to achieve better seismic readings than its competitors via patented sensor-to-borehole coupling mechanism. It is the hope that the commercialization of this device will not only provide a more affordable alternative to engineers and geophysicists in the existing market, but the significant cost difference may open new seismic measurement opportunities in the developing world. Its compact size and light weight will increase mobility, allowing investigators …
Comparison Of The Ground-Motion Attenuation Relationship Between The Wenchuan, China, Area And The Central And Eastern United States, Jiwei Feng, Zhenming Wang, Edward W. Woolery, Shanyou Li
Comparison Of The Ground-Motion Attenuation Relationship Between The Wenchuan, China, Area And The Central And Eastern United States, Jiwei Feng, Zhenming Wang, Edward W. Woolery, Shanyou Li
Report of Investigations--KGS
An Mw-7.9 earthquake occurred in Wenchuan, China, in 2008, along the Longmenshan Fault, which is located on the western border of the South China stable continental region. A detailed comparison of the Wenchuan ground-motion attenuation relationships with the relationships for the central and eastern United States (also a stable continental region) showed that the ground-motion prediction equation for the Wenchuan area is similar to those for the central and eastern United States. Thus, the strong-motion records from the Wenchuan earthquake can be used for constraining the ground-motion prediction equation and engineering analysis for the central and eastern United …
Assessing The Relative Mobility Of Submarine Landslides From Deposit Morphology And Physical Properties: An Example From Kumano Basin, Nankai Trough, Offshore Japan, Zachary T. Moore
Theses and Dissertations--Earth and Environmental Sciences
A prominent landslide deposit in the Slope Basin seaward of the Megasplay Fault in the Nankai Trough was emplaced by a high-mobility landslide based on analysis of physical properties and seismic geomorphology. Slide acceleration is a critical variable that determines amplitude of slide-generated tsunami but is many times a variable with large uncertainty. In recent controlled laboratory experiments, the ratio of the shear stress to yield strength (defined as the Flow Factor) controls a wide spectrum of mass movement styles from slow, retrogressive failure to rapid, liquefied flows. Here, we apply this laboratory Flow Factor approach to a natural landslide …
Finding Mars Paleopoles From Magnetization Edge Effects To Determine The History Of Mars’ Core Dynamo, Melissa Lynn Ditty
Finding Mars Paleopoles From Magnetization Edge Effects To Determine The History Of Mars’ Core Dynamo, Melissa Lynn Ditty
Theses and Dissertations--Earth and Environmental Sciences
This is a new method of determining magnetization strength, direction, and paleopole location from magnetic anomalies across edges of the equatorial band of magnetic sources on Mars. Different assumed locations of paleopoles result in different inducing field directions in the vicinity of an edge. Thus, with different paleopoles, the resulting magnetic fields from the edges of magnetic sources are different, and correlate differently with the observed fields. Best correlating observed and computed magnetic edge effect fields yield the potential paleopoles. The total gradient (TG) of the z-component magnetic field was used to identify the edges of magnetization boundaries. Three edge …
Depth To Curie Temperature Across The Central Red Sea From Magnetic Data Using The De-Fractal Method, Ahmed Salem, Chris Green, Dhananjay Ravat, Kumar Hemant Singh, Paul East, J. Derek Fairhead, Saad Mogren, Ed Biegert
Depth To Curie Temperature Across The Central Red Sea From Magnetic Data Using The De-Fractal Method, Ahmed Salem, Chris Green, Dhananjay Ravat, Kumar Hemant Singh, Paul East, J. Derek Fairhead, Saad Mogren, Ed Biegert
Earth and Environmental Sciences Faculty Publications
The central Red Sea rift is considered to be an embryonic ocean. It is characterised by high heat flow, with more than 90% of the heat flow measurements exceeding the world mean and high values extending to the coasts — providing good prospects for geothermal energy resources. In this study, we aim to map the depth to the Curie isotherm (580 °C) in the central Red Sea based on magnetic data. A modified spectral analysis technique, the “de-fractal spec- tral depth method” is developed and used to estimate the top and bottom boundaries of the magnetised layer. We use a …
Science And Public Policy Of Earthquake Hazard Mitigation In The New Madrid Seismic Zone, Alice M. Orton
Science And Public Policy Of Earthquake Hazard Mitigation In The New Madrid Seismic Zone, Alice M. Orton
Theses and Dissertations--Earth and Environmental Sciences
In the central United States, undefined earthquake sources, long earthquake recurrence intervals and uncertain ground motion attenuation models have contributed to an overstatement of regional seismic hazard for the New Madrid Seismic Zone on the National Seismic Hazard Maps. This study examined concerns regarding scientific uncertainties, overly stringent seismic mitigation policies and depressed local economy in western Kentucky through a series of informal interviews with local businessmen, public officials, and other professionals in occupations associated with seismic mitigation. Scientific and relative economic analyses were then performed using scenario earthquake models developed with FEMA’s Hazus-MH software. Effects of the 2008 Wenchuan …
Using Time-Lapse Three Dimensional Vertical Seismic Profiling To Monitor Injected Fluids During Geologic Carbon Sequestration, John B. Hickman
Using Time-Lapse Three Dimensional Vertical Seismic Profiling To Monitor Injected Fluids During Geologic Carbon Sequestration, John B. Hickman
Report of Investigations--KGS
Two three-dimensional vertical seismic profiles (3D-VSP) were acquired at the KGS Marvin Blan No. 1 CO2 sequestration research well outside of Cloverport in Hancock County, Ky. The initial (preinjection) survey was performed September 15-16, 2010, and was followed by the injection of 361.2 metric tons of supercritical CO2 and then 584 m3 of 2 percent potassium chloride water (to displace the remaining CO2 in the wellbore) on September 22, 2010. After injection, the well was shut in with a downhole pressure of 17.5 MPa at the injected reservoir depth of 1,545.3 m. A second 3D-VSP was …
Instrument Correction And Dynamic Site Profile Validation At The Central United States Seismic Observatory, New Madrid Seismic Zone, Clayton M.J. Brengman
Instrument Correction And Dynamic Site Profile Validation At The Central United States Seismic Observatory, New Madrid Seismic Zone, Clayton M.J. Brengman
Theses and Dissertations--Earth and Environmental Sciences
The Central United States Seismic Observatory (CUSSO), is a fifteen-element array of three-component accelerometers and seismometers in the New Madrid seismic zone, within the upper Mississippi embayment. Its location within the thick (up to 1 km) sequences of unlithified sediment comprising the embayment, make CUSSO a unique array in its ability to directly measure seismic wave propagation, including ground motion site effect; however, before the observational data can be used for analysis, the orientation and instrument response of the CUSSO array must be defined. This study used cross-correlation and direct comparisons to filter out the instrument response and determine the …
Application Of The Kalman Filter On Full Tensor Gravity Gradiometry Data Around The Vinton Salt Dome, Louisiana, Mahnaz Sepehrmanesh
Application Of The Kalman Filter On Full Tensor Gravity Gradiometry Data Around The Vinton Salt Dome, Louisiana, Mahnaz Sepehrmanesh
Theses and Dissertations--Earth and Environmental Sciences
Full tensor gravity (FTG) data are known for their high resolution but also for higher noise in its components due to the dynamic nature of the platform used for data acquisition. Although a review of the literature suggests steady increase in the success of gravity gradiometry, we still cannot take advantage of the full potential of the method, mostly because of the noise with the same amplitude and wavenumber characteristics as the signal that affects these data. Smoothing from common low pass filters removes small wavelength features and makes it difficult to detect structural features and other density variations of …
Seismic Velocity Database For The New Madrid Seismic Zone And Its Vicinity, Qian Li, Edward W. Woolery, Matthew M. Crawford, David M. Vance
Seismic Velocity Database For The New Madrid Seismic Zone And Its Vicinity, Qian Li, Edward W. Woolery, Matthew M. Crawford, David M. Vance
Information Circular--KGS
Over the last 20 years, researchers at the University of Kentucky have collected seismic-reflection and refraction data to characterize seismic velocity models of the soil-sediment overburden throughout the central United States. The data are in different forms, such as published reports, theses, and journal articles, and in digital form. In order to construct a unified database for easier management, access, and use, Microsoft Access was used to design the data structure and field properties. The database consists of four tables with unified field names, data type, and units. An ArcGIS geodatabase with the same data structure as the Access database …
Shear-Wave Imaging And Birefringence In A Complex Near-Surface Geological Environment, Ali Z. Almayahi
Shear-Wave Imaging And Birefringence In A Complex Near-Surface Geological Environment, Ali Z. Almayahi
Theses and Dissertations--Earth and Environmental Sciences
Multiple geophysical and geological data sets were compiled, reprocessed, and interpreted using state-of-the-art signal processing and modeling algorithms to characterize the complex post-Paleozoic geology that overlies the southwestern projection of the Fluorspar Area Fault Complex (FAFC) in western Kentucky. Specific data included 21.5 km of SH-wave seismic reflection, 1.5 km of P-wave seismic reflection, 2 km of electrical resistivity, vertical seismic profiles, Vp and Vs sonic-suspension logs, and 930 lithologic borehole logs. The resultant model indicates three general northeast–southwest-oriented fault zones pass through the study area as southwestern extensions of parts of the FAFC. These fault zones form two significant …
Sh-Wave Refraction And Reflection Investigation Of Quaternary Geology―Central United States Seismic Observatory, Carrington L. Wright
Sh-Wave Refraction And Reflection Investigation Of Quaternary Geology―Central United States Seismic Observatory, Carrington L. Wright
Theses and Dissertations--Earth and Environmental Sciences
The Central United States Seismic Observatory (CUSSO) consists of an array of vertical strong motion accelerometers and medium period seismometers that penetrate 585 m into the Mississippi Embayment sediments and terminates into Paleozoic bedrock. The array is located in the New Madrid Seismic Zone within the upper embayment. The thick unconsolidated Quaternary sediments have the potential to influence strong motions; understanding how these sediments affect ground motion is the goal of the CUSSO array. Nine SH-wave refraction and five P-wave common midpoint reflection surveys were collected within a 1 km radius around the CUSSO borehole in order to characterize the …
Ground Motion For The Maximum Credible Earthquake In Kentucky, Zhenming Wang
Ground Motion For The Maximum Credible Earthquake In Kentucky, Zhenming Wang
Report of Investigations--KGS
Although they are not frequent, earthquakes occur in and around Kentucky and pose certain hazards. Assessing seismic hazards is challenging, however, because of a lack of observations. The best estimates of ground motions that could be expected if the maximum credible earthquake occurs in or around Kentucky are depicted in maps showing peak ground acceleration and short-period (0.2 second) and long-period (1.0 second) response accelerations with 5 percent critical damping on hard rock. Another consideration for seismic safety is that the maximum credible earthquake has a long recurrenece interval, from 500 to 1,000 years in the New Madrid Seismic Zone …
Long-Period Ground Motions In The Upper Mississippi Embayment From Finite-Fault, Finite-Difference Simulations, Kenneth A. Macpherson
Long-Period Ground Motions In The Upper Mississippi Embayment From Finite-Fault, Finite-Difference Simulations, Kenneth A. Macpherson
University of Kentucky Doctoral Dissertations
A 3D velocity model and 3D wave propagation code have been employed to simulate long-period ground motions in the upper Mississippi embayment. This region is exposed to seismic hazard in the form of large earthquakes in the New Madrid seismic zone and observational data are sparse, making simulation a valuable tool for predicting the effects of large events. These simulations were undertaken in order to estimate ground-motion characteristics and to investigate the influence of the 3D embayment structure and finite-fault mechanics. There are three primary fault zones in the New Madrid seismic zone, each of which was likely associated with …
Assessing The Felt Reports Of The 1811-12 New Madrid Earthquakes In The Central United States, Ron Street, John D. Kiefer, Jerry L. Raisor
Assessing The Felt Reports Of The 1811-12 New Madrid Earthquakes In The Central United States, Ron Street, John D. Kiefer, Jerry L. Raisor
Report of Investigations--KGS
The damage and felt reports describing the New Madrid, Mo., earthquakes of 1811-12 need to be assessed in the historical context in which the events occurred. Log cabins in the frontier settlements along the lower Ohio River Valley, for example, were built with a rudimentary form of base isolation, and their response to the earthquakes should not be evaluated in the same way that a modern wood-frame or brick building would be.
Also, inaccuracies have crept into the databases used for estimating the epicenters and magnitudes of the earthquakes. For example, the magnitude of the December 16, 1811, earthquake has …
Considerations Of Variations In Ionospheric Field Effects In Mapping Equatorial Lithospheric Magsat Magnetic Anomalies, Dhananjay Ravat, W. J. Hinze
Considerations Of Variations In Ionospheric Field Effects In Mapping Equatorial Lithospheric Magsat Magnetic Anomalies, Dhananjay Ravat, W. J. Hinze
Earth and Environmental Sciences Faculty Publications
Longitudinal, seasonal, and altitude‐dependent variability of magnetic fields is investigated in equatorial latitudes to determine their effect on the isolation of lithospheric Magsat magnetic anomalies. An estimate of ‘ionospheric effect’ was compiled by averaging the total intensity Magsat anomalies as a function of dip latitudes (called ‘dip‐latitude averages’) from dawn and dusk data sets grouped according to longitudes, time (months), and altitudes. Unanticipated seasonal variations were observed in dusk Magsat data over the Indian sector that may contribute to an improved understanding of the equatorial electrojet. The amplitudes of the dawn dip‐latitude averages are small in comparison to the dusk …
Statistical Prediction Of Satellite Magnetic Anomalies, H. K. Goyal, R. R. B. Von Frese, W. J. Hinze, D. N. Ravat
Statistical Prediction Of Satellite Magnetic Anomalies, H. K. Goyal, R. R. B. Von Frese, W. J. Hinze, D. N. Ravat
Earth and Environmental Sciences Faculty Publications
The geological utility of satellite magnetic observations is limited by orbital altitude variations which may be as large as a few hundred kilometres. This study investigates the use of fast and elegant statistical procedures for altitude normalization and gridding of magnetic anomaly data as an alternative to more commonly used equivalent source inversion procedures involving computationally extensive and complex least‐squares matrix methods. A standard statistical approach for gridding satellite magnetic anomalies is to recompute numerically averaged values from three‐dimensionally distributed observations which are within two standard deviations of an initially determined averaged anomaly estimate. the errors of this procedure for …
Response Of Saturated Sands To Cyclic Shear At Earthquake Amplitudes, Vincent P. Drnevich, John P. Jent
Response Of Saturated Sands To Cyclic Shear At Earthquake Amplitudes, Vincent P. Drnevich, John P. Jent
KWRRI Research Reports
Both quasi-static and resonant cyclic shear tests were performed on hollow cylindrical specimens of saturated sands at various densities and confining stresses. Shear moduli measured at nondestructive amplitudes were shown to be independent of frequency for the range of 0.1Hz to 50Hz. Application of cyclic shear at larger amplitudes caused effective stresses to decrease and failure. The number of cycles to failure was related to ratio of cyclic shear stress to maximum drained shear stress. Effective confining stress reduces approximately linearly with number of cycles. Shear modulus and shear damping.can be described by the Hardin-Drnevich equations if change in effective …
Location Of Solution Channels And Sinkholes At Dam Sites And Backwater Areas By Seismic Methods: Part Ii, Vincent P. Drnevich, D. Raghu
Location Of Solution Channels And Sinkholes At Dam Sites And Backwater Areas By Seismic Methods: Part Ii, Vincent P. Drnevich, D. Raghu
KWRRI Research Reports
Four seismic field methods and a laboratory method are used to determine shear wave propagation velocities and shear moduli for two sites. The four seismic methods are: standard seismic refraction survey, down hole shooting refraction survey, transient Rayleigh wave survey, and crosshole shooting survey. A torsional resonant column apparatus was used for the laboratory tests. The cross hole shooting method gave the best results because direct measurements were made. Criteria for using this method are given. Methods which measure compression wave velocity give inconsistent results because the conversion to shear wave velocity is very sensitive to Poisson's ratio. Laboratory tests …
Location Of Solution Channels And Sinkholes At Dam Sites And Backwater Areas By Seismic Methods: Part I, Vincent P. Drnevich, S. R. Smith, E. P. Cleveland
Location Of Solution Channels And Sinkholes At Dam Sites And Backwater Areas By Seismic Methods: Part I, Vincent P. Drnevich, S. R. Smith, E. P. Cleveland
KWRRI Research Reports
The basic concepts associated with the sledge hammer seismic refraction survey are reviewed and a modified version called down hole shooting is discussed. The latter method has distinct advantages for rock surface profiling. These include: calibration at the end points of the survey, measurement of vertical wave propagation velocities directly, and having a refracted wave ray path for almost the entire survey length.
The down hole shooting seismic refraction survey has been simulated with the digital computer. The method can handle any shaped rock surface profile and generates corresponding travel time curves for the forward and reverse profile surveys. This …