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Nanoscale Evidence For Temperature-Induced Transient Rheology And Postseismic Fault Healing, Alexis K. Ault, Jordan L. Jensen, Robert G. Mcdermott, F.-A. Shen, B. R. Van Devener Oct 2019

Nanoscale Evidence For Temperature-Induced Transient Rheology And Postseismic Fault Healing, Alexis K. Ault, Jordan L. Jensen, Robert G. Mcdermott, F.-A. Shen, B. R. Van Devener

Geosciences Faculty Publications

Friction-generated heat and the subsequent thermal evolution control fault material properties and thus strength during the earthquake cycle. We document evidence for transient, nanoscale fault rheology on a high-gloss, light-reflective hematite fault mirror (FM). The FM cuts specularite with minor quartz from the Pleistocene El Laco Fe-ore deposit, northern Chile. Scanning and transmission electron microscopy data reveal that the FM volume comprises a2+ suboxides. Sub–5-nm-thick silica films encase hematite grains and connect to amorphous interstitial silica. Observations imply that coseismic shear heating (temperature >1000 °C) generated transiently amorphous, intermixed but immiscible, and rheologically weak Fe-oxide and silica. Hematite regrowth in …


Evaluation Of Pre-Eruptive Conditions For Cordon Caulle Rhyo-Dacitic Historic Eruptions, Mauro Andres Mingo Jun 2019

Evaluation Of Pre-Eruptive Conditions For Cordon Caulle Rhyo-Dacitic Historic Eruptions, Mauro Andres Mingo

FIU Electronic Theses and Dissertations

For better understanding of Plinian-hybrid eruptive events, I analyzed the variables that affect the pre-eruptive conditions of the latest three eruptive events of the Puyehue Cordon Caulle Volcanic Complex (PCCVC). The analysis was done by performing a petrological study of lava samples followed by Electron Probe Microanalysis (EPMA) on selected mineral phases. Mineral data were then used in established mathematical models to calculate pre-eruptive magma temperature and water content. The acquired data are compared to bulk measured water content, and the difference is utilized to estimate viscosities and evaluate the degassing regime. Results indicate that the historic eruptive events have …


Examination Of The Climate Factors That Reduced Wheat Yield In Northwest India During The 2000s, Avik Mukherjee, Shih-Yu (Simon) Wang, Parichart Promchote Feb 2019

Examination Of The Climate Factors That Reduced Wheat Yield In Northwest India During The 2000s, Avik Mukherjee, Shih-Yu (Simon) Wang, Parichart Promchote

Plants, Soils, and Climate Faculty Publications

In India, a significant reduction of wheat yield would cause a widespread impact on food security for 1.35 billion people. The two highest wheat producing states, Punjab and Haryana in northern India, experienced a prolonged period of anomalously low wheat yield during 2002–2010. The extent of climate variability and change in influencing this prolonged reduction in wheat yield was examined. Daily air temperature (Tmax and Tave) was used to calculate the number of days above optimum temperature and growing degree days (GDD) anomaly. Two drought indices, the standard precipitation and evapotranspiration index and the radiation-based precipitation index, …


Carbon Dioxide Measurement In Irish Blanket Peatlands: An Assessment Of Pool-Soil Flux Variability, Mariya Radomski, Alan Gilmer, Vivienne Byers, Eugene Mcgovern Jan 2019

Carbon Dioxide Measurement In Irish Blanket Peatlands: An Assessment Of Pool-Soil Flux Variability, Mariya Radomski, Alan Gilmer, Vivienne Byers, Eugene Mcgovern

Articles

Peatlands have been recognised as having a significant role in the mediation of atmospheric carbon dioxide (CO2) levels with direct implications for global climate change. Longitudinal in situ measurement systems for CO2 concentrations in blanket peatland ecosystems are difficult to implement where the nature of terrestrial–aquatic connectivity and hydrodynamics have a significant effect on the carbon cycle. The need for greater data on CO2 concentrations and flux monitoring in these settings has been well recognised. However, applying the most appropriate monitoring approach presents a special challenge. This paper sets out the development of a direct method for field based longitudinal …


Meteorological Comparison Of Three Cave Systems, Matthew Wine Jan 2019

Meteorological Comparison Of Three Cave Systems, Matthew Wine

Mahurin Honors College Capstone Experience/Thesis Projects

Cave systems are home to delicate underground ecosystems that can be affected by changes in surface atmospheric conditions which in turn affect underground meteorology. Modern human use of caves is typically for tourism, so understanding surface-underground weather-climate interactions is important when caves carry streams that are prone to flooding in response to surface precipitation. The purpose of this research is to document the effects of surface weather conditions on cave meteorology in three different cave system types located in different geographic locations including an island, the central USA, and at high elevations in British Columbia. The study caves include Kaumana …