Geophysics and Seismology Commons^™

Collisional Reactivation Of Rift Margin Fracture Zones, Taiwan And The Taconic Allochthon, David C. Mirakian

Master's Theses

Chapter I. Transverse Topographic Development due to the Reactivation of a Partially-Subducted Fracture Zone: The Southwest Hsüehshan Range, Central Taiwan

Abstract — The southwest flank of the Hsüehshan Range is defined by a topographic break which cuts across regionally mapped structures in central Taiwan. The mountain front trends ~345°, slightly oblique to the Sanyi-Puli seismic zone which has been previously interpreted as a reactivated continental margin fracture zone. Structural data collected along the length of the topographic break reveal two populations of cross-cutting faults with distinct fault-zone materials and a series of southwest-plunging folds. Paleostress axes were reconstructed using the …

3-D Transient Hydraulic Tomography In Unconfined Aquifers With Fast Drainage Response, Michael Cardiff, Warren Barrash

CGISS Publications and Presentations

We investigate, through numerical experiments, the viability of three-dimensional transient hydraulic tomography (3DTHT) for identifying the spatial distribution of groundwater flow parameters (primarily, hydraulic conductivity K) in permeable, unconfined aquifers. To invert the large amount of transient data collected from 3DTHT surveys, we utilize an iterative geostatistical inversion strategy in which outer iterations progressively increase the number of data points fitted and inner iterations solve the quasi-linear geostatistical formulas of Kitanidis. In order to base our numerical experiments around realistic scenarios, we utilize pumping rates, geometries, and test lengths similar to those attainable during 3DTHT field campaigns performed at …

Hydrological Parameter Estimations From A Conservative Tracer Test With Variable-Density Effects At The Boise Hydrogeophysical Research Site, B. Dafflon, Warren Barrash, Michael Cardiff, T. C. Johnson

CGISS Publications and Presentations

Reliable predictions of groundwater flow and solute transport require an estimation of the detailed distribution of the parameters (e.g., hydraulic conductivity, effective porosity) controlling these processes. However, such parameters are difficult to estimate because of the inaccessibility and complexity of the subsurface. In this regard, developments in parameter estimation techniques and investigations of field experiments are still challenging and necessary to improve our understanding and the prediction of hydrological processes. Here we analyze a conservative tracer test conducted at the Boise Hydrogeophysical Research Site in 2001 in a heterogeneous unconfined fluvial aquifer. Some relevant characteristics of this test include: variable-density …

Co2 Sequestration In Basalt: Carbonate Mineralization And Fluid Substitution, Thomas L. Otheim, Ludmila Adam, Kasper Van Wijk, Michael L. Batzle, Travis Mcling, Robert Podgorney

CGISS Publications and Presentations

Geologicalsequestration of carbon dioxide in deep reservoirs may provide alarge-scale option for reducing the emissions of this gas intothe atmosphere. The effectiveness of sequestration depends on the storagecapacity and stability of the reservoir and risk of leakageinto the overburden. Reservoir rocks can react with a CO₂-watermixture, potentially resulting in the precipitation of minerals in theavailable matrix pore space and within pre-existing fractures. This inducedmineralization may form internal seals that could help mitigate theleakage of CO₂ into the overburden. For basaltic host rocks,carbonic acid partially dissolves minerals in the host rock, suchas the calcium plagioclase mineral, freeing various …

Effects Of High-Impedance-Contrast Boundary Upon Multi-Modal Seismic Surface Wave Data, Prajwol Tamrakar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Synthetic studies and analyses of an experimental dataset were conducted to address the use of Rayleigh-type surface waves for estimation of shear wave velocity (VS) profiles of shallow bedrock sites. The shallow bedrock presents a high impedance contrast boundary which causes surface wave energy to be partitioned to higher modes. Idealized studies of hypothetical datasets and root-mean-squared calculations of error surfaces showed that if reliable dispersion data are available over a broad frequency spectrum, the VS profile can be recovered using the fundamental mode alone. However, when dispersion data are limited to a relatively narrow frequency band representing what might …

Stratigraphic Record Of Holocene Coseismic Subsidence, Padang, West Sumatra, Tina Dura, Charles M. Rubin, Harvey M. Kelsey, Benjamin P. Horton, Andrea Hawkes, Christopher H. Vane, Mudrik Daryono, Candace Grand Pre, Tyler Landinsky, Sarah Bradley

All Faculty Scholarship for the College of the Sciences

Stratigraphic evidence is found for two coseismic subsidence events that underlie a floodplain 20 km south of Padang, West Sumatra along the Mentawai segment (0.5°S–0.3°S) of the Sunda subduction zone. Each earthquake is marked by a sharp soil‐mud contact that represents a sudden change from mangrove to tidal flat. The earthquakes occurred about 4000 and 3000 cal years B.P. based on radiocarbon ages of detrital plant fragments and seeds. The absence of younger paleoseismic evidence suggests that late Holocene relative sea level fall left the floodplain too high for an earthquake to lower it into the intertidal zone. Our results …

A Simplified Approach For Estimating Soil Carbon And Nitrogen Stocks In Semi-Arid Complex Terrain, Melvin L. Kunkel, Alejandro N. Flores, Toni J. Smith, James P. Mcnamara, Shawn G. Benner

Geosciences Faculty Publications and Presentations

We investigated soil carbon (C) and nitrogen (N) distribution and developed a model, using readily available geospatial data, to predict that distribution across a mountainous, semi-arid, watershed in southwestern Idaho (USA). Soil core samples were collected and analyzed from 133 locations at 6 depths (n=798), revealing that aspect dramatically influences the distribution of C and N, with north-facing slopes exhibiting up to 5 times more C and N than adjacent southfacing aspects. These differences are superimposed upon an elevation (precipitation) gradient, with soil C and N contents increasing by nearly a factor of 10 from the bottom (1100 m elevation) …

Quasi 3-Dimensional Electrical Resistivity Mapping Of Air-Filled Karst Conduits And Policy Implications, Charles W. Mccrackin

USF Tampa Graduate Theses and Dissertations

This study assesses the capability and practical applications of quasi 3-Dimensional (3D) electrical resistivity surveying (ER) for mapping air-filled karst conduits. Vadose zone caves within the Brooksville Ridge of West Central Florida are relatively similar in architecture, with N-S elongation, and do not consist of an interconnected network of conduits. A high resolution quasi-3D ER survey was performed over two mapped cave systems on the Brooksville Ridge. The resultant survey verified the general effectiveness of quasi-3D ER in locating the two known near-surface cave features. Several other locations in the survey show similar or stronger resistivity anomalies trending in a …

Geogram 2011, David J. Keeling Editor, Wku Department Of Geography And Geology

Earth, Environmental, and Atmospheric Sciences Publications

No abstract provided.

Paleomagnetism And Investigation Of 40 Ma Lavas, Liverpool Range, New South Whales, Australia, Nathan M. Padilla

Physics

The main focus of this project is the continued study of a reversal of the earth’s magnetic field recorded from lavas in the Liverpool Range of New South Whales, Australia. This reverse-to-normal transition, recently dated at ~40 Ma, was first reported in Nature in 1986. [2] In March 2011 some 200+ cores were drilled from several sections about the volcanic range—Jemmy’s Creek, Bald Hill, Rock Creek, Yarraman, and Coolah Tops Road. Here we focus on paleomagnetic findings from samples drilled from the most extensive section, that being along the trail near Jemmy’s Creek. Results from alternating field demagnetization show the …

Magnetic Properties Of Ilmenite‐Hematite Single Crystals From The Ecstall Pluton Near Prince Rupert, British Columbia, Sarah J. Brownlee, Joshua M. Feinberg, Takeshi Kasama, Richard J. Harrison, Gary R. Scott, Paul R. Renne

Environmental Science and Geology Faculty Research Publications

Paleomagnetic studies of the 91 Ma Ecstall pluton and other Cretaceous plutons of British Columbia imply large northward tectonic movements (>2000 km) may have occurred during the tectonic evolution of western North America. However, more recent studies have shown that the eastern edge of the Ecstall pluton experienced considerable mineralogical changes as younger Eocene plutons, such as the ∼58 Ma Quottoon Pluton, were emplaced along its margins. We investigated changes in the rock magnetic properties associated with this reheating event by examining isolated grains of intergrown ilmenite and hematite, the primary paleomagnetic recorder in the Ecstall pluton. Measurements of …

Theory And Laboratory Experiments Of Elastic Wave Scattering By Dry Planar Fractures, Thomas E. Blum, Roel Snieder, Kasper Van Wijk, Mark E. Willis

CGISS Publications and Presentations

Remote sensing of fractures with elastic waves is important in fields ranging from seismology to nondestructive testing. In many geophysical applications, fractures control the flow of fluids such as water, hydrocarbons or magma. While previous analytic descriptions of scattering mostly deal with very large or very small fractures (compared to the dominant wavelength), we present an analytic solution for the scattering of elastic waves from a fracture of arbitrary size. Based on the linear slip model for a dry fracture, we derive the scattering amplitude in the frequency domain under the Born approximation for all combinations of incident and scattered …

Estimating The Rayleigh-Wave Impulse Response Between Seismic Stations With The Cross Terms Of The Green Tensor, Kasper Van Wijk, T. Dylan Mikesell, Vera Schulte-Pelkum, Josh Stachnik

CGISS Publications and Presentations

The development of ambient noise tomography has provided a powerful tool to investigate the Earth's subsurface with increased resolution. Most commonly, surface-wave tomography is performed on inter-station estimates of the vertical component of Rayleigh waves, stemming from crosscorrelations of ocean-generated noise. Here, we estimate the cross terms of the Rayleigh-wave Green tensor, and show this is less sensitive to signal not in-line with the seismic stations. We illustrate this result with the Batholiths temporary seismic deployment, showing estimates of the Rayleigh wave with a higher signal-to-noise ratio and a consequently better phase-velocity dispersion curve. This approach provides an opportunity for …

Predicted Velocity And Density Structure Of The Exhuming Papua New Guinea Ultrahigh‐Pressure Terrane, Sarah J. Brownlee, Bradley R. Hacker, Matthew Salisbury, Gareth Seward, Timothy A. Little, Suzanne A. Baldwin, Geoffrey A. Abers

Environmental Science and Geology Faculty Research Publications

New electron backscatter diffraction measurements show that the Papua New Guinea (PNG) ultrahigh‐pressure (UHP) terrane is dominated by rocks with weakly oriented quartz and feldspar and less abundant strongly oriented hornblende, clinopyroxene, and mica. Velocities measured at high pressures (600 MPa) show that V_P is 5.8–6.3 km/s for gneiss samples, 6.5–7.7 km/s for amphibolite, and 7.7–8.2 km/s for eclogite and V_S is 3.4–3.9 km/s for gneiss, 4.0–4.4 km/s for amphibolite, and 4.5–4.6 km/s for eclogite. Velocities and anisotropies calculated from mineral crystal preferred orientations (CPOs) are equivalent to within 5% of the measured values. The highest seismic anisotropy …

Exploring Methods For Earthquake Prediction: The Effects Of Water On The Flow Of Stress-Activated Electric Currents In Igneous Rocks, Aaron M. Jahoda, Friedemann T. Freund

STAR Program Research Presentations

Much of the devastation and damage of earthquakes can be attributed to the fact that they occur suddenly and without much warning, which limits the ability of people to evacuate and/or properly prepare. One method, however, that might be used to predict seismic events is the generation of electric currents in rocks when stresses are applied. It is observed in this research that the application of direct force onto samples of igneous rock causes the rocks to generate a measurable current, which is attributed to positive-hole charges moving within the oxygen sub-lattice. Because large and changing forces are acted upon …

Penrose Conference Report: Neotectonics Of Arc-Continent Collision, Paul Mann, Carlos Vargas, Caroline Whitehill

Geological Sciences Faculty Scholarship

Collisions of arcs with continents are some of the most significant tectonic processes on Earth, leading to crustal accretion, continental growth, formation of sedimentary basins, large areas of regional uplift and deformation, complex interactions between continuous and torn subducted slabs and the surrounding mantle, and large regions of large earthquakes and seismic, volcanic, and landslide hazards that can threaten the lives of millions.
The objective of this conference was to bring together an international group of scientists to discuss the neotectonics and seismic hazards of shallow slab subduction in areas of arc-continent collisions.

Establishing Confidence In Surface Wave Determined Soil Profiles, Paul Michaels

CGISS Publications and Presentations

Surface waves can be used to determine the shear velocity profile from the ground surface to some depth limited by the spectral band of the seismic source. A number of factors influence the uncertainties of the determined profile. The field acquisition factors include the deployment geometry of geophones, the spectral characteristics of the geophones, recording instruments, and seismic source. A key data processing factor is the determination of a dispersion curve from the field recordings. Finally, there are important choices in conducting the inversion of the dispersion curve which leads to the final soil profile. Even if the field factors …

Full Conference Program With Abstracts, Jason S. Polk, Leslie A. North

International 2011 Conference on Karst Hydrogeology and Ecosystems

No abstract provided.

Groundwater Research In Middle Earth, Thomas Lapoint

Liberal Arts and Engineering Studies

My senior project focused on studying saltwater intrusion in a coastal town of New Zealand. I feel lucky that I was able to travel to such a distant place, conduct research that was insightful and interesting, and immerse myself in an international culture all in the name of my education. As a Liberal Arts and Engineering Studies student, I aim to analyze not only the cultural differences and similarities that the foreign environment offers to me but also the detailed, technical, engineering aspect of my research. I believe that my education should be approached with a well rounded perspective that …

Effect Of Attenuation Relationships On Seismic Site Response Analysis, Maryam Motamed

Morehead State Theses and Dissertations

Presented to the faculty of the College of Science and Technology at Morehead State University in partial fulfillment of the requirement for the Degree of Master of Science by Maryam Motamed on May 12, 2011.

Interpretation Of Rayleigh-Wave Ellipticity Observed With Multicomponent Passive Seismic Interferometry At Hekla Volcano, Iceland, Matthew M. Haney, Andrew Nies, Tim Masterlark, Sarah Needy, Rikke Pedersen

CGISS Publications and Presentations

The 2010 eruption of Eyjafjallajökull has drawn increased attention to Iceland’s Eastern Volcanic Zone (EVZ) due to the threat it poses to the heavily used air-traffic corridors of the northern Atlantic Ocean. Within the EVZ, Hekla is historically one of the most active volcanoes and has exhibited a decadal eruption pattern for the past 40 years. Hekla most recently erupted in 2000 and is thus ripe for another decadal eruption. Because Hekla is generally aseismic, except for a brief time period (hours) leading up to an eruption, monitoring has previously depended on precursory deformation signals (Linde et al., 1993). As …

Complex Vs Profiles To 100 M Depth From Rayleigh Waves And 3-D Vs Model For Las Vegas Valley, Helena Murvosh

UNLV Theses, Dissertations, Professional Papers, and Capstones

A three-dimensional (3-D) shear wave velocity (VS) model was developed for the heterogeneous shallow sediments (to nearly 400 m) of the Las Vegas Valley (LVV), Nevada. The model was based on more than 200 VS profiles and 1400 geologic well logs. Five sediment units including a cemented unit were defined from geologic log descriptions. A characteristic VS profile for four of the units was obtained by correlating between closely spaced pairs of VS and sediment data; a constant VS was assigned to the cemented unit. VS profiles were then assigned to each well location based on type of sediment according …

Elastic Plastic Self Consistent (Epsc) Modeling Of Plastic Deformation In Fayalite Olivine, Christopher J. Cline Ii, Pamela Burnley

Festival of Communities: UG Symposium (Posters)

We are using an Elastic Plastic Self Consistent Model (a type of numerical simulation) to study deformation of olivine. Olivine is one of the major constituents of the Earth’s upper mantle and its deformation properties have an important influence on how the Earth’s crust deforms. For example, the flow strength of olivine limits the size of the largest earthquakes and the heights of the tallest mountains on Earth. By comparing the results of our simulations with data from olivine deformation experiments we are able to better interpret the experimental data.

In-Situ Synchrotron X-Ray Diffraction Study Of Quartz Deformation Using The D-Dia Apparatus, May Sas, Dawn Pape, Brian Erickson, Sylvia-Monique Thomas, Pamela Burnley

Festival of Communities: UG Symposium (Posters)

Deformation is a rock’s mechanical response to external parameters such as temperature and pressure. Knowledge of deformation is necessary to understand geodynamic processes. The behavior of rocks and minerals during deformation depends on the behavior of individual grains within those minerals as they interact. The mineral we are studying is quartz, which we chose since it is very well studied and is highly abundant. We use high-pressure high temperature experiments to simulate conditions of Earth’s interior and the D-DIA apparatus combined with synchrotron x-ray diffraction allows us to record data directly during the process of deformation. The data we collect …

Relation Of Recent Seismicity (1988-Present) To The 1958 Huslia, Alaska Earthquake Sequence, Abigail Monreal^, Diane I. Doser*

COURI Symposium Abstracts, Spring 2011

We have examined how recent seismicity in the Huslia region of central Alaska is related to active faults and the 1958 earthquake sequence (with at least 3 events of magnitude >6). Most of this region is swampy lowland dominated by alluvial material deposited by the Koyukuk River, making surficial identification of active faults difficult.  This portion of Alaska is also of interest because it appears to be a region in transition between the strike-slip faulting of the Salcha-Fairbanks-Minto Flats seismic zone and normal faulting of western Alaska (Norton Sound/Seward Peninsula). Researchers have suggested this change in the nature of faulting …

Mapping Unmarked Graves In The Mescalero Apache Indian Reservation, Ashley Galusina Nauer^, Stephanie Chavez^, Laura Serpa*

COURI Symposium Abstracts, Spring 2011

Citizens living on the Apache Indian Reservation in Mescalero, New Mexico have experienced difficulty in burying their dead because when they dig a new grave, they often find a body from an earlier burial. The reservation does not have rigorous rules on locating and marking graves and, thus, there are numerous unmarked burial sites within and outside of the existing cemeteries. Officials from the reservation approached the Geological Sciences Department for assistance to map grave locations in the area’s three graveyards. In this project, we will use shallow ground-penetrating radar (GPR) to find the graves and digital global positioning system …

Studies Of Seismicity Near The Active Volcano Mt. Spurr, Sarah J. Olivas^, Diane I. Doser*

COURI Symposium Abstracts, Spring 2011

Seismicity patterns and fault orientations can indicate local stress fields related to volcanic eruptions. There have been many moderate magnitude, shallow earthquakes occurring in the Strandline Lake region about 100km from Anchorage, Alaska near the active volcano, Mt. Spurr. Previous researchers have found that the local stress under Mt. Spurr, before and after its 1992 eruption (1992-1997), differed from the regional stresses, which are related to subduction of the Pacific Plate and Yakutat micro plate. We are analyzing location and patterns of earthquakes occurring since 1998 to determine if more recent seismicity is similar to that occurring before or after …

Using Gravitational And Magnetic Data To Understand Interactions Between Active Seismic Zones Within The Interior Of Alaska, Shane M. Schinagel^, Diane I. Doser*

COURI Symposium Abstracts, Spring 2011

Differences in rock density, along with changes in the orientation of the magnetic field, provide vital information about the tectonic environment within the interior of Alaska in a region where outcrop exposure is poor due to recent glacial and fluvial activity.  Analysis of the gravity and magnetic field can help identify relationships between recent (1989-2008) and historic (pre-1971) seismicity and suspected strike-slip, reverse, and thrust faults within the region, as differences in density and magnetic properties of materials may be observed across fault zones.  Our overall objective is to better understand the complicated interactions between the strike-slip Denali fault system …

Seismic Study Of Carlsbad, Nm, Steven M. Espinosa^, Aaron A. Velasco*

COURI Symposium Abstracts, Spring 2011

Since January 1, 2000, there have been numerous earthquakes recorded in the vicinity of Carlsbad, NM.  Importantly, these shallow (10km) earthquakes with magnitudes < 4.3, do not have a fault or system of faults directly mapped to explain these events.  We will be relocating the largest and most recent earthquake, which occurred 25km west of Carlsbad, NM of magnitude 4.1 on March 28, 2010. Data recorded by seismic stations from the USArray, a large National Science Foundation project, and our local Kidd Observatory will be used for this analysis. The use of Standing Order of Data (SOD) allows us access seismograms, and the Seismic Analysis Code (SAC) helps in the analysis of the seismic data.   We will correlate the hypocenters of aftershocks to the main event hypocenter, allowing us to identify the fault plane.  Once a fault plane has been identified, we will begin work on relocating a second event, thereby identifying the responsible faults.  We believe that faulting in this area is related to the Rio Grande Rift extension and can be used as evidence for an active rift.

Possible Connections Between A Great Earthquake And An Earthquake Sequence: Samoa Islands (8.1) And Vanuatu Islands, Marissa Cameron^, Aaron A. Velasco*

COURI Symposium Abstracts, Spring 2011

Dynamic triggering describes the possibility that certain earthquakes cause, or ‘trigger’ new earthquakes at great distances. Static triggering is common and is known to cause aftershocks very near to the site, generally within two lengths of the ruptured fault.  Dynamically triggered events can occur at distances beyond two fault lengths, however the mechanism for how this can occur remains unknown. By examining seismic data collected from possible dynamically triggered events, we may gain a better understanding of the mechanisms at work. On September 29, 2009, an earthquake of magnitude 8.1 took place along a 175 km fault rupture in Samoa, …