Geophysics and Seismology Commons^™

The Strange Physics Of Low Frequency Mirror Mode Turbulence In The High Temperature Plasma Of The Magnetosheath, R. A. Treumann, C. H. Jaroschek, O. D. Constantinescu, R. Nakamura

Dartmouth Scholarship

Mirror mode turbulence is the lowest frequency perpendicular magnetic excitation in magnetized plasma proposed already about half a century ago by Rudakov and Sagdeev (1958) and Chandrasekhar et al. (1958) from fluid theory. Its experimental verification required a relatively long time. It was early recognized that mirror modes for being excited require a transverse pressure (or temperature) anisotropy. In principle mirror modes are some version of slow mode waves. Fluid theory, however, does not give a correct physical picture of the mirror mode. The linear infinitesimally small amplitude physics is described correctly only by including the full kinetic theory and …

Effects Of Signal Processing And Antenna Frequency On The Geostatistical Structure Of Ground-Penetrating Radar Data, Greg A. Oldenborger, Michael D. Knoll, Warren Barrash

CGISS Publications and Presentations

Recent research has suggested that the geostatistical structure of ground-penetrating radar data may be representative of the spatial structure of hydraulic properties. However, radar images of the subsurface can change drastically with application of signal processing or by changing the signal frequency. We perform geostatistical analyses of surface radar reflection profiles in order to investigate the effects of data processing and antenna frequency on the semivariogram structure of radar reflection amplitudes. Surface radar reflection data collected at the Boise Hydrogeophysical Research Site illustrate the processing- and antenna-dependence of radar semivariograms for a fluvial, cobble-and-sand aquifer. Compensating for signal attenuation and …

Modeling Long-Term Volcanic Hazards Through Bayesian Inference: An Example From The Tohoku Volcanic Arc, Japan, Andrew J. Martin, Koji Umeda, Charles B. Connor, Jennifer N. Weller, Dapeng Zhao, Masaki Takahashi

Geology Faculty Publications

The need to quantitatively estimate future locations of volcanoes in the long-term is of increasing importance, partly as a result of the requirement of constructing certain types of installations in regions of low geologic risk. The complex geological factors and natural processes controlling the locations of volcanoes make it problematic to estimate future patterns deterministically. Instead, the probabilistic approach can be developed with quite high levels of confidence; however, for regions with few or no volcanoes, there is a need to include additional geological and geophysical data that may indicate the likelihood of future volcanism. We achieve this using Bayesian …

Geogram 2004, David J. Keeling Editor, Wku Department Of Geography And Geology

Earth, Environmental, and Atmospheric Sciences Publications

No abstract provided.

Lithium Abundance And Isotope Systematics Of Forearc Serpentinites, Conical Seamount, Mariana Forearc: Insights Into The Mechanics Of Slab-Mantle Exchange During Subduction, Laurie D. Benton, Jeffrey G. Ryan, Ivan P. Savov

Geology Faculty Publications

[1] Variable lithium contents and contrasting Li isotopic signatures are evident in the serpentininite muds and clasts extruded at Conical Seamount in the Mariana forearc. The muds have high Li contents compared to mantle values (3–7 ppm) and a mean δ7Li value of ∼+6‰. The clasts are generally lower in Li, and δ7Li varies from −6‰ to +10‰, with higher δ7Li correlating broadly to higher lithium contents. The diverse δ7Li in the serpentinite clasts suggests Li exchanges between mantle rocks and evolving slab‐derived fluids from different depths, producing a subarc mantle that is zoned in terms of Li abundances and …

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

All Faculty Scholarship for the College of the Sciences

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 …

Seismic Expression Of Pleistocene Paleoceanographic Changes In The California Borderland From Digitally Acquired 3.5 Khz Subbottom Profiles And Ocean Drilling Program Leg 167 Drilling, Aleksandra Janik, Mitchell W. Lyle, Lee M. Liberty

CGISS Publications and Presentations

We correlate processed 3.5 kHz seismic profiles with physical properties of cores collected during ODP Leg 167 from the Tanner, East Cortes, and San Nicolas Basins through much of the Pleistocene succession. Results indicate that seismic horizons in the unconsolidated Pleistocene sediments (top 50 m) are mainly controlled by density contrasts. Removing of the compaction trend from the density reveals a very interesting relationship between density and composition - the density closely and inversely correlates with organic carbon indicating that large-scale variations in organic carbon are responsible for seismic reflections through their influence on density. This is a significant discovery …

What's Shakin': Earthquake Research At Bridgewater, Robert C. Cicerone

Bridgewater Review

No abstract provided.

A Long Baseline Laser Strainmeter For The Exploratory Studies Facility At Yucca Mountain, Frank K. Wyatt, James N. Brune, Drew Coleman, Don Baepler, Amy J. Smiecinski

Publications (YM)

This Scientific Investigation Plan (SIP), for work under the second Department of Energy/University and Community College System of Nevada (DOE/UCCSN) Cooperative Agreement (10/01/03), DEFC28- 04RW12232, is intended to cover the laser strainmeter operation and monitoring task being conducted by the University of California, San Diego (UCSD), under the oversight of the Nevada Seismological Laboratory of the University of Nevada-Reno (NSL/UNR). UCSD has carried out the design, engineering, and installation of the east-west laser strainmeter (LSM) currently in place in the Exploratory Studies Facility (ESF) at Yucca Mountain.

Quantitative Analysis Of Movement Along An Earthquake Thrust Scarp: A Case Study Of A Vertical Exposure Of The 1999 Surface Rupture Of The Chelungpu Fault At Wufeng, Western Taiwan, Jian-Cheng Lee, Charles Rubin, Karl Mueller, Yue-Gau Chen, Yu-Chang Chan, Kerry Sieh, Hao-Tsu Chu, Wen-Shan Chen

All Faculty Scholarship for the College of the Sciences

A vertical exposure across the principal thrust scarp of the 1999 Mw 7.6 earthquake allows quantification of fault slip. The exposure is located on the active Chelungpu fault near Wufeng, along the range front of the fold-and-thrust belt in western Taiwan. The 1999 surface ruptures at the Wufeng site are characterized by a west-facing 2 to 3 m high principal thrust scarp and an east-facing lesser backthrust scarp. We mapped a 15 m-long, 5 m-deep exposure across the principal thrust scarp and characterized complex deformation structures, which include a main basal thrust fault, a wedge thrust, and a pop-up anticlinal …

Spatial Variation In The Response Of Tree Rings To Normal Faulting During The Hebgen Lake Earthquake, Southwestern Montana, Usa, Matthew F. Bekker

Wasatch Dendroclimatology Research

Tree rings have frequently been used to identify the effects of earthquakes on forests, but little is known about spatial variation in the response of trees to intraplate normal faulting. This paper documents and describes the effects of tree location (distance from and position above or below the fault scarp), size and age on the response of tree rings to the 1959 magnitude 7.5 Hebgen Lake earthquake, which occurred along a normal fault in the Gallatin National Forest in southwestern Montana. Core samples from 88 trees were collected along nine 100-m transects straddling the Hebgen scarp, and from 28 additional …

Crossing A Narrow-In-Altitude Turbulent Auroral Acceleration Region, R. Pottelette, R. A. Treumann, E. Georgescu

Dartmouth Scholarship

We report on the in situ identification of a narrow electrostatic acceleration layer (electrostatic shock) containing intense plasma turbulence in the upward current region, and its effect on auroral particles. Wave turbulence recorded in the center of the layer differs in character from that recorded above and beneath. It is concluded that the shock is sustained by different nonlinear waves which, at each level, act on the particles in such a way to produce a net upward directed electric field. The main power is in the ion acoustic range. We point out that anomalous resistivities are incapable of locally generating …

Error Analysis Of Continuous Gps Position Time Series, Simon D. P. Williams, Yehuda Bock, Peng Fang, Paul Jamason, Rosanne M. Nikolaidis, Linette Prawirodirdjo, Meghan Miller, Daniel J. Johnson

All Faculty Scholarship for the College of the Sciences

A total of 954 continuous GPS position time series from 414 individual sites in nine different GPS solutions were analyzed for noise content using maximum likelihood estimation (MLE). The lengths of the series varied from around 16 months to over 10 years. MLE was used to analyze the data in two ways. In the first analysis the noise was assumed to be white noise only, a combination of white noise plus flicker noise, or a combination of white noise plus random walk noise. For the second analysis the spectral index and amplitude of the power law noise were estimated simultaneously …

Detection Of Arbitrarily Large Dynamic Ground Motions With A Dense High-Rate Gps Network, Yehuda Bock, Linette Prawirodirdjo, Timothy I. Melbourne

All Faculty Scholarship for the College of the Sciences

We describe the detection of teleseismic surface waves from the 3 November 2002 Mw 7.9 Denali fault earthquake in Alaska with a dense network of 1 Hz GPS stations in southern California, about 3900 km from the event. Relative horizontal displacements with amplitudes in excess of 15 mm and duration of 700 seconds agree with integrated velocities recorded by nearby broadband seismometers with an rms difference of 2–3 mm. The displacements are derived from independent 1 Hz instantaneous positions demonstrating that a GPS network can provide direct measurements of arbitrarily large dynamic and static ground horizontal displacements at periods longer …

Time Dependent Mechanical Behavior Of Welded Tuff, Jaak J.K. Daemen, George Danko, Amy J. Smiecinski

Publications (YM)

This part of the Technical Report includes four types of experimental studies: strain rate dependence, uniaxial creep, Brazilian (Indirect splitting) tensile strength and uniaxial compressive strength. These are presented in four chapters. One hundred twenty one specimens have been tested in uniaxial compression. Ninety three of these are included in the strain rate dependence study, presented in Chapter 2. Uniaxial compression strain rates range from about 10~8 to 10~2 s~l. Results of twenty eight tests are presented in Chapter 5, which describes uniaxial compression testing of specimens containing major lithophysal cavities. Fourteen specimens have been tested in uniaxial creep, presented …

Vsp Traveltime Inversion: Near-Surface Issues, Geoff J. M. Moret, William P. Clement, Michael D. Knoll, Warren Barrash

Geosciences Faculty Publications and Presentations

P-wave velocity information obtained from vertical seismic profiles (VSPs) can be useful in imaging subsurface structure, either by directly detecting changes in the subsurface or as an aid to the interpretation of seismic reflection data. In the shallow subsurface, P-wave velocity can change by nearly an order of magnitude over a short distance, so curved rays are needed to accurately model VSP traveltimes. We used a curved-ray inversion to estimate the velocity profile and the discrepancy principle to estimate the data noise level and to choose the optimum regularization parameter. The curved-ray routine performed better than a straight-ray inversion for …

Inside Unlv, Gian Galassi, Carol C. Harter, Kenneth E. Marks

Inside UNLV

No abstract provided.

Drift Scale Test: Analyze And Report, George Danko, Davood Bahrami, Amy J. Smiecinski

Publications (YM)

This report summarizes the results of the in situ thermophysical properties measurements as part of the Drift Scale Test (DST) measurement program at Yucca Mountain, Nevada. Thermophysical measurements have been performed with three built-in thermal probes since November 13, 1997 and were expected to continue for three more years until the end of the DST cooling period. The Department of Energy (DOE), under Cooperative Agreement, Number DEFC28- 98NV12081, has funded a research project at the University of Nevada, Reno since November, 1999 titled: "Continuing site characterization and performance verification applications with the REKA method at Yucca Mountain, Task 13." This …

Southern Great Basin Seismic Network Operations, David Von Seggern, James N. Brune, Rasool Anooshehpoor, Drew Coleman, Don Baepler, Amy J. Smiecinski

Publications (YM)

QAP-3.0 (Scientific Investigation Control) of the University and Community College System of Nevada (UCCSN) Quality Assurance (QA) program requires that, prior to initiating work, a Scientific Investigation Plan (SIP) must be prepared and approved. This SIP is intended to cover the seismic monitoring task performed by the Nevada Seismological Laboratory (NSL). The purpose of this SIP is to describe the high-level planning for the overall task such that it can be referred to by individual scientific notebooks. Due to the continuation nature of this task, this SIP contains language that may be considered generic so that new subtasks …

Multivariate Analysis Of Cross-Hole Georadar Velocity And Attenuation Tomograms For Aquifer Zonation, Jens Tronicke, Klaus Holliger, Warren Barrash, Michael D. Knoll

CGISS Publications and Presentations

We have investigated the potential of combining cross-hole georadar velocity and attenuation tomography as a method for characterizing heterogeneous alluvial aquifers. A multivariate statistical technique, known as k-means cluster analysis, is used to correlate and integrate information contained in velocity and attenuation tomograms. Cluster analysis allows us to identify objectively the major common trends in the tomographic data and thus to ‘‘reduce’’ the information to a limited number of characteristic parameter combinations. The application of this procedure to two synthetic data sets indicates that it is a powerful tool for converting the complex relationships between the tomographically derived velocity …

Image Compression And Its Effect On Data, Khaled S. Alkharabsheh

Theses, Dissertations and Capstones

This thesis is intended to define and study different image compression techniques, software programs, image formats (from early ones such as “GIF” to most recent ones such as “JPEG 2000”), compression effect on compressed data (compressed images), and its effectiveness and usefulness in reducing the file size and its transmission time, as a result.

In many GeoBioPhysical applications, some information inside any image may be the keys to solve different kinds of problems and classify features. This kind of data and information has to be handled with care; i.e. it’s not allowed to be lost during the compression process. On …

Mae Sae Basin And Wiang Nong Lom: Radiocarbon Dating And Relation To The Active Strike-Slip Mae Chan Fault, Northern Thailand, Spencer H. Wood, Fongsaward S. Singharajwarapan, Tharaporn Bundarnsin, Eric Rothwell

Geosciences Faculty Publications and Presentations

The Mai Sai basin and the Wiang Nong Lom swamp lie north of, and adjacent to, the northeast-trending Mae Chan fault, which is a left -lateral strike-slip fault in northernmost Thailand. The sediment in the Mae Sai basin is about 600 meters thick. The Mae Sai basin has an anticlinal fold below a 390-meter depth. This fold is buried by broadly downwarped sediment. In the Wiang Nong Lom swamp, sediment is about 170 meters thick. Radiocarbon ages from a 2.7-meter auger hole at Ko Mae Mai in the Wiang Nong Lom swamp show that 0.5 meter of sediment accumulated in …

Experimental Determination Of Stiffness Of Joints In Welded Tuff, Jaak J.K. Daemen, George Danko, Amy J. Smiecinski

Publications (YM)

Fourteen uniaxial joint compression tests were run to determine the normal and shear stiffnesses of type 1 fracture joints (healed joints filled with vapor-phase mineral deposits) obtained from the Yucca Mountain site. The uniaxial joint compression results show that these joints behave linearly up to over 85% of their loading history. They are stiff with strengths very close to the strength of the intact rock. Five direct shear tests were run on open, separated, joints. Results obtained from the direct shear testing show that the normal stiffness increases with increasing normal stress. Shearing through asperities gives high joint shear stiffness …

Design Of Geophysical Surveys In Transportation, Paul Michaels

CGISS Publications and Presentations

Designing geophysical investigations for transportation related projects requires special attention to the constraints imposed by right-of-way, irregular topography, noise from traffic, and the need to avoid the interruption of traffic flow. A geophysical engineer needs to be prepared to consider these design issues that are not addressed in a standard procedure such as ASTM D-5777. The author presents design strategies that address these issues, and illustrates the concepts with case histories taken from bridge and highway projects. Beam steering, broadside shooting, and non-traditional designs that preserve alternative analysis options are presented. Transportation engineers who augment traditional subsurface geotechnical surveys with …

Potential Contaminants At A Dredged Spoil Placement Site, Charles City County, Virginia, As Revealed By Sequential Extraction, Jianwu Tang, G. Richard Whittecar, Karen H. Johannesson, W. Lee Daniels

OES Faculty Publications

Backfills of dredged sediments onto a former sand and gravel mine site in Charles City County, VA may have the potential to contaminate local groundwater. To evaluate the mobility of trace elements and to identify the potential contaminants from the dredged sediments, a sequential extraction scheme was used to partition trace elements associated with the sediments from the local aquifer and the dredged sediments into five fractions: exchangeable, acidic, reducible, oxidizable, and residual phases. Sequential extractions indicate that, for most of the trace elements examined, the residual phases account for the largest proportion of the total concentrations, and their total …

Implications Of X-Ray Emission From Lightning, Joseph R. Dwyer

Aerospace, Physics, and Space Science Faculty Publications

Dwyer et al. [2003, 2004a] recently reported measurements of bursts of x-rays, with energies up to ∼250 keV, originating from dart leaders and possibly the return strokes of rocket-triggered lightning. In this paper, these x-ray observations are compared with the relativistic runaway electron avalanche (RREA) model. It is found that for dart leaders the standard RREA model is inconsistent with the observed spectrum and flux of the x-ray emission. This result implies that the cold runaway electron model may be applicable to dart leaders. In this model, runaway electrons are directly accelerated out of the bulk electron population, produced by …

Nonlinear Guiding Center Theory Of Perpendicular Diffusion: General Properties And Comparison With Observation, John W. Bieber, William H. Matthaeus, Andreas Shalchi, Gang Qin

Aerospace, Physics, and Space Science Faculty Publications

A nonlinear guiding center (NLGC) theory for diffusion of charged particles perpendicular to the mean magnetic field was recently proposed. Here, we draw attention to a number of attractive features of this theory: (1) The theory provides a natural mechanism to connect the perpendicular mean free path with the parallel mean free path. In fact, the parallel mean free path is the only particle property required to determine uniquely the perpendicular mean free path. (2) Under a broad range of conditions, the theory predicts that the perpendicular mean free path will be of order one percent or a few percent …

Structural Analysis Of The Gonic Formation In Berwick, Maine, Joseph F. Renda

Geology Theses and Dissertations

RELATIONSHIP OF THE GONIC FORMATION AND NONSUCH RIVER FAULT TO THE NORUMBEGA FAULT ZONE IN BERWICK, MAINE
Located in southwestern Maine the Gonic Formation abuts the Nonesuch River Fault of the Norumbega Fault System. The rock types of the Gonic Fm. consist
predominantly of micaceous schist and lesser amounts of quartzite. Fieldwork suggests that the units have undergone transposition and thus appear to be
interlayered and pinch-out along strike. Granitoid rocks have also been observed and are interpreted as related to either the Lyman Pluton or White Mountain
Complex and serve as the backbone to the line of low-lying hills …

In Situ Stress, Fracture, And Fluid Flow Analysis In Well 38c-9: An Enhanced Geothermal System In The Coso Geothermal Field, Judith M. Sheridan, Stephen H. Hickman

United States Geological Survey: Staff Publications

Geoscientists from the Coso Operating Company, EGI-Utah, GeoMechanics International, and the United States Geological Survey are cooperating in a multi-year study to develop an Enhanced Geothermal System (EGS) in the Coso Geothermal Field. Key to the creation of an EGS is an understanding of the relationship among natural fracture distribution, fluid flow, and the ambient tectonic stresses that exist within the resource in order to design a hydraulic and thermal stimulation of an east-flank injection well, the first step in the creation of a heat exchanger at depth. Well datasets from the east flank of the Coso Geothermal Field are …

Modeled And Observed Empirical Orthogonal Functions Of Currents In The Yucatan Channel, Gulf Of Mexico, Lie-Yauw Oey, Tal Ezer, Wilton Sturges

CCPO Publications

Candela et al. [2003] have reported empirical orthogonal function (EOF) analyses based on 23-month current-meter and acoustic Doppler current profiler measurements in the Yucatan Channel. Those authors noted the difference between EOFs obtained from observations and their z-level models and EOFs calculated by Ezer et al. [2003] from the results of a terrain-following model. Here a new analysis is reported that explains this difference, and that also suggests the importance of shelf-edge meander mode of the core Loop Current in the channel. We show that the terrain-following model gives EOFs with characteristics similar to those observed when data from the …