Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Keyword
Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Investigations Into The Degassing And Eruption Mechanisms Of Nyamuragira Volcano, Democratic Republic Of The Congo (Africa) , Elisabet Marie Head
Investigations Into The Degassing And Eruption Mechanisms Of Nyamuragira Volcano, Democratic Republic Of The Congo (Africa) , Elisabet Marie Head
Dissertations, Master's Theses and Master's Reports - Open
One of two active volcanoes in the western branch of the East African Rift, Nyamuragira (1.408ºS, 29.20ºE; 3058 m) is located in the D.R. Congo. Nyamuragira emits large amounts of SO2 (up to ~1 Mt/day) and erupts low-silica, alkalic lavas, which achieve flow rates of up to ~20 km/hr. The source of the large SO2 emissions and pre-eruptive magma conditions were unknown prior to this study, and 1994-2010 lava volumes were only recently mapped via satellite imagery, mainly due to the region’s political instability. In this study, new olivine-hosted melt inclusion volatile (H2O, CO2, S, …
Comparison Of Magnetic Properties And Petrography Between Dykes And Lava Flows From La Cienega, New Mexico And Thunder Bay Area, Canada, Elise A. Desplas
Comparison Of Magnetic Properties And Petrography Between Dykes And Lava Flows From La Cienega, New Mexico And Thunder Bay Area, Canada, Elise A. Desplas
Dissertations, Master's Theses and Master's Reports - Open
Data on the evolution of geomagnetic paleointensity are crucial for understanding the geodynamo and Earth’s thermal history. Although basaltic flows are preferred for paleointensity experiments, quickly cooled mafic dykes have also been used. However, the paleointensity values obtained from the dykes are systematically lower than those from lava flows. This bias may originate from the difference in cooling histories and resultant magnetic mineralogies of extrusive and intrusive rocks. To explore this hypothesis, the magnetic mineralogy of two feeder dyke-lave flow systems, from Thunder Bay (Canada) and La Cienega (New-Mexico), has been studied using magnetic and microscopy methods. Within each system, …
Comparing Satellite And Ground-Based Observations Of Paroxysmal Degassing Events At Etna Volcano, Italy, Céline L. Mandon
Comparing Satellite And Ground-Based Observations Of Paroxysmal Degassing Events At Etna Volcano, Italy, Céline L. Mandon
Dissertations, Master's Theses and Master's Reports - Open
Mount Etna, Italy, is one of the most active volcanoes in the world, and is also regarded as one of the strongest volcanic sources of sulfur dioxide (SO2) emissions to the atmosphere. Since October 2004, an automated ultraviolet (UV) spectrometer network (FLAME) has provided ground-based SO2 measurements with high temporal resolution, providing an opportunity to validate satellite SO2 measurements at Etna. The Ozone Monitoring Instrument (OMI) on the NASA Aura satellite, which makes global daily measurements of trace gases in the atmosphere, was used to compare SO2 amount released by the volcano during paroxysmal lava-fountaining …
Lava Discharge Rate Estimates From Thermal Infrared Satellite Data At Pacaya Volcano, Guatemala , Hilary A. Morgan
Lava Discharge Rate Estimates From Thermal Infrared Satellite Data At Pacaya Volcano, Guatemala , Hilary A. Morgan
Dissertations, Master's Theses and Master's Reports - Open
Time-averaged discharge rates (TADR) were calculated for five lava flows at Pacaya Volcano (Guatemala), using an adapted version of a previously developed satellite-based model. Imagery acquired during periods of effusive activity between the years 2000 and 2010 were obtained from two sensors of differing temporal and spatial resolutions; the Moderate Resolution Imaging Spectroradiometer (MODIS), and the Geostationary Operational Environmental Satellites (GOES) Imager. A total of 2873 MODIS and 2642 GOES images were searched manually for volcanic “hot spots”. It was found that MODIS imagery, with superior spatial resolution, produced better results than GOES imagery, so only MODIS data were used …
Remote Sensing Of Volcanic Plumes Using The Advanced Spaceborne Thermal Emission And Reflection Radiometer (Aster)., Lorna Alison Henney
Remote Sensing Of Volcanic Plumes Using The Advanced Spaceborne Thermal Emission And Reflection Radiometer (Aster)., Lorna Alison Henney
Dissertations, Master's Theses and Master's Reports - Open
The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) has been used to quantify SO2 emissions from passively degassing volcanoes. This dissertation explores ASTER’s capability to detect SO2 with satellite validation, enhancement techniques and extensive processing of images at a variety of volcanoes. ASTER is compared to the Mini UV Spectrometer (MUSe), a ground based instrument, to determine if reasonable SO2 fluxes can be quantified from a plume emitted from Lascar, Chile. The two sensors were in good agreement with ASTER proving to be a reliable detector of SO2. ASTER illustrated the advantages of imaging a …
Slope Stability Analysis Of The Pacaya Volcano, Guatemala, Using Limit Equilibrium And Finite Element Method , Patrick. Manzoni
Slope Stability Analysis Of The Pacaya Volcano, Guatemala, Using Limit Equilibrium And Finite Element Method , Patrick. Manzoni
Dissertations, Master's Theses and Master's Reports - Open
The Pacaya volcanic complex is part of the Central American volcanic arc, which is associated with the subduction of the Cocos tectonic plate under the Caribbean plate. Located 30 km south of Guatemala City, Pacaya is situated on the southern rim of the Amatitlan Caldera. It is the largest post-caldera volcano, and has been one of Central America’s most active volcanoes over the last 500 years. Between 400 and 2000 years B.P, the Pacaya volcano had experienced a huge collapse, which resulted in the formation of horseshoe-shaped scarp that is still visible. In the recent years, several smaller collapses have …
Sampling Bias In Evaluating The Probability Of Seismically Induced Soil Liquefaction With Spt & Cpt Case Histories, Abhishek Jain
Sampling Bias In Evaluating The Probability Of Seismically Induced Soil Liquefaction With Spt & Cpt Case Histories, Abhishek Jain
Dissertations, Master's Theses and Master's Reports - Open
Several deterministic and probabilistic methods are used to evaluate the probability of seismically induced liquefaction of a soil. The probabilistic models usually possess some uncertainty in that model and uncertainties in the parameters used to develop that model. These model uncertainties vary from one statistical model to another. Most of the model uncertainties are epistemic, and can be addressed through appropriate knowledge of the statistical model. One such epistemic model uncertainty in evaluating liquefaction potential using a probabilistic model such as logistic regression is sampling bias. Sampling bias is the difference between the class distribution in the sample used for …
Geotechnical Data And Numerical Analysis Of Edifice Collapse And Related Hazards At Pacaya Volcano, Guatemala, Lauren N. Schaefer
Geotechnical Data And Numerical Analysis Of Edifice Collapse And Related Hazards At Pacaya Volcano, Guatemala, Lauren N. Schaefer
Dissertations, Master's Theses and Master's Reports - Open
The continual eruptive activity, occurrence of an ancestral catastrophic collapse, and inherent geologic features of Pacaya volcano (Guatemala) demands an evaluation of potential collapse hazards. This thesis merges techniques in the field and laboratory for a better rock mass characterization of volcanic slopes and slope stability evaluation. New field geological, structural, rock mechanical and geotechnical data on Pacaya is reported and is integrated with laboratory tests to better define the physical-mechanical rock mass properties. Additionally, this data is used in numerical models for the quantitative evaluation of lateral instability of large sector collapses and shallow landslides. Regional tectonics and local …
Using Auto- And Cross-Correlations From Seismic Noise To Monitor Velocity Changes At Villarrica Volcano, Chile, Kathleen F. Mckee
Using Auto- And Cross-Correlations From Seismic Noise To Monitor Velocity Changes At Villarrica Volcano, Chile, Kathleen F. Mckee
Dissertations, Master's Theses and Master's Reports - Open
We used the Green's functions from auto-correlations and cross-correlations of seismic ambient noise to monitor temporal velocity changes in the subsurface at Villarrica volcano in the Southern Andes of Chile. Campaigns were conducted from March to October 2010 and February to April 2011 with 8 broadband and 6 short-period stations, respectively. We prepared the data by removing the instrument response, normalizing with a root-mean-square method, whitening the spectra, and filtering from 1 to 10 Hz. This frequency band was chosen based on the relatively high background noise level in that range. Hour-long auto- and cross-correlations were computed and the Green's …