Bill Evans, PhD (Former Employee)
Science and Products
Filter Total Items: 110
The comparative limnology of Lakes Nyos and Monoun, Cameroon The comparative limnology of Lakes Nyos and Monoun, Cameroon
Lakes Nyos and Monoun are known for the dangerous accumulation of CO2 dissolved in stagnant bottom water, but the shallow waters that conceal this hazard are dilute and undergo seasonal changes similar to other deep crater lakes in the tropics. Here we discuss these changes with reference to climatic and water-column data collected at both lakes during the years following the gas release...
Authors
George Kling, William C Evans, Gregory Tanyileke
Developing a new, passive diffusion sampling array to detect helium anomalies associated with volcanic unrest Developing a new, passive diffusion sampling array to detect helium anomalies associated with volcanic unrest
Helium (He) concentration and 3 He/ 4 He anomalies in soil gas and spring water are potentially powerful tools for investigating hydrothermal circulation associated with volca- nism and could perhaps serve as part of a hazards warning system. However, in operational practice, He and other gases are often sampled only after volcanic unrest is detected by other means. A new passive...
Authors
Brittany E Dame, D Kip Solomon, William C. Evans, Steven E. Ingebritsen
Magmatic gas emissions at Holocene volcanic features near Mono Lake, California, and their relation to regional magmatism Magmatic gas emissions at Holocene volcanic features near Mono Lake, California, and their relation to regional magmatism
Silicic lavas have erupted repeatedly in the Mono Basin over the past few thousand years, forming the massive domes and coulees of the Mono Craters chain and the smaller island vents in Mono Lake. We report here on the first systematic study of magmatic CO2 emissions from these features, conducted during 2007–2010. Most notably, a known locus of weak steam venting on the summit of North...
Authors
D. Bergfeld, William C. Evans, James F. Howle, Andrew G. Hunt
Hydrothermal monitoring in a quiescent volcanic arc: Cascade Range, northwestern United States Hydrothermal monitoring in a quiescent volcanic arc: Cascade Range, northwestern United States
Ongoing (1996–present) volcanic unrest near South Sister, Oregon, is accompanied by a striking set of hydrothermal anomalies, including elevated temperatures, elevated major ion concentrations, and 3He/4He ratios as large as 8.6 RA in slightly thermal springs. These observations prompted the US Geological Survey to begin a systematic hydrothermal-monitoring effort encompassing 25 sites...
Authors
Steven E. Ingebritsen, N. G. Randolph-Flagg, Katrina D. Gelwick, Elizabeth A. Lundstrom, Ilana M. Crankshaw, Anna M. Murveit, M.E. Schmidt, Deborah Bergfeld, Kurt R. Spicer, David S. Tucker, Robert H. Mariner, William C. Evans
Crustal migration of CO2-rich magmatic fluids recorded by tree-ring radiocarbon and seismicity at Mammoth Mountain, CA, USA Crustal migration of CO2-rich magmatic fluids recorded by tree-ring radiocarbon and seismicity at Mammoth Mountain, CA, USA
Unrest at Mammoth Mountain over the past several decades, manifest by seismicity, ground deformation, diffuse CO2 emissions, and elevated 3He/4He ratios in fumarolic gases has been driven by the release of CO2-rich fluids from basaltic intrusions in the middle to lower crust. Recent unrest included the occurrence of three lower-crustal (32–19 km depth) seismic swarms beneath Mammoth...
Authors
Jennifer L. Lewicki, George E. Hilley, David R. Shelly, John C. King, John P. McGeehin, Margaret T. Mangan, William C. Evans
Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone
Helium is used as a critical tracer throughout the Earth sciences, where its relatively simple isotopic systematics is used to trace degassing from the mantle, to date groundwater and to time the rise of continents1. The hydrothermal system at Yellowstone National Park is famous for its high helium-3/helium-4 isotope ratio, commonly cited as evidence for a deep mantle source for the...
Authors
Jacob B. Lowenstern, William C. Evans, D. Bergfeld, Andrew G. Hunt
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 110
The comparative limnology of Lakes Nyos and Monoun, Cameroon The comparative limnology of Lakes Nyos and Monoun, Cameroon
Lakes Nyos and Monoun are known for the dangerous accumulation of CO2 dissolved in stagnant bottom water, but the shallow waters that conceal this hazard are dilute and undergo seasonal changes similar to other deep crater lakes in the tropics. Here we discuss these changes with reference to climatic and water-column data collected at both lakes during the years following the gas release...
Authors
George Kling, William C Evans, Gregory Tanyileke
Developing a new, passive diffusion sampling array to detect helium anomalies associated with volcanic unrest Developing a new, passive diffusion sampling array to detect helium anomalies associated with volcanic unrest
Helium (He) concentration and 3 He/ 4 He anomalies in soil gas and spring water are potentially powerful tools for investigating hydrothermal circulation associated with volca- nism and could perhaps serve as part of a hazards warning system. However, in operational practice, He and other gases are often sampled only after volcanic unrest is detected by other means. A new passive...
Authors
Brittany E Dame, D Kip Solomon, William C. Evans, Steven E. Ingebritsen
Magmatic gas emissions at Holocene volcanic features near Mono Lake, California, and their relation to regional magmatism Magmatic gas emissions at Holocene volcanic features near Mono Lake, California, and their relation to regional magmatism
Silicic lavas have erupted repeatedly in the Mono Basin over the past few thousand years, forming the massive domes and coulees of the Mono Craters chain and the smaller island vents in Mono Lake. We report here on the first systematic study of magmatic CO2 emissions from these features, conducted during 2007–2010. Most notably, a known locus of weak steam venting on the summit of North...
Authors
D. Bergfeld, William C. Evans, James F. Howle, Andrew G. Hunt
Hydrothermal monitoring in a quiescent volcanic arc: Cascade Range, northwestern United States Hydrothermal monitoring in a quiescent volcanic arc: Cascade Range, northwestern United States
Ongoing (1996–present) volcanic unrest near South Sister, Oregon, is accompanied by a striking set of hydrothermal anomalies, including elevated temperatures, elevated major ion concentrations, and 3He/4He ratios as large as 8.6 RA in slightly thermal springs. These observations prompted the US Geological Survey to begin a systematic hydrothermal-monitoring effort encompassing 25 sites...
Authors
Steven E. Ingebritsen, N. G. Randolph-Flagg, Katrina D. Gelwick, Elizabeth A. Lundstrom, Ilana M. Crankshaw, Anna M. Murveit, M.E. Schmidt, Deborah Bergfeld, Kurt R. Spicer, David S. Tucker, Robert H. Mariner, William C. Evans
Crustal migration of CO2-rich magmatic fluids recorded by tree-ring radiocarbon and seismicity at Mammoth Mountain, CA, USA Crustal migration of CO2-rich magmatic fluids recorded by tree-ring radiocarbon and seismicity at Mammoth Mountain, CA, USA
Unrest at Mammoth Mountain over the past several decades, manifest by seismicity, ground deformation, diffuse CO2 emissions, and elevated 3He/4He ratios in fumarolic gases has been driven by the release of CO2-rich fluids from basaltic intrusions in the middle to lower crust. Recent unrest included the occurrence of three lower-crustal (32–19 km depth) seismic swarms beneath Mammoth...
Authors
Jennifer L. Lewicki, George E. Hilley, David R. Shelly, John C. King, John P. McGeehin, Margaret T. Mangan, William C. Evans
Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone
Helium is used as a critical tracer throughout the Earth sciences, where its relatively simple isotopic systematics is used to trace degassing from the mantle, to date groundwater and to time the rise of continents1. The hydrothermal system at Yellowstone National Park is famous for its high helium-3/helium-4 isotope ratio, commonly cited as evidence for a deep mantle source for the...
Authors
Jacob B. Lowenstern, William C. Evans, D. Bergfeld, Andrew G. Hunt
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.