Bill Evans, PhD
My research focused on volcanic volatiles and water-rock interaction in geothermal systems.
Gases are an important factor in volcanic hazards because of their role in driving explosive eruptions and their intrinsic toxicity. Part of the answer to, “What could happen?” at a restless volcano comes from gas studies. The mechanism of gas generation at depth and gas migration up through boiling hydrothermal systems, cold groundwaters, and the unsaturated zone are all complex processes that are only partly understood. The goal of my research is to use gas flux, composition, and isotope values to refine our general understanding of these processes and to apply this information to studies that focus on the behavior and hazards of individual volcanoes. The research involved identifying the areas of highest interest, planning the field investigations, determining the most appropriate sampling protocol, analyzing for the bulk composition and isotopic characteristics of the gas, and interpreting and publishing the results.
Science and Products
Chemical and isotopic data on gases and waters for thermal and non-thermal features across Yellowstone National Park (2003-2015)
Fumarole gas geochemistry and tree-ring radiocarbon data at Mammoth Mountain, California (1989-2016)
Geochemistry and fluxes of gases from hydrothermal features at Newberry Volcano, Oregon, USA
Groundwater dynamics at Kīlauea Volcano and vicinity, Hawaiʻi
A post-eruption study of gases and thermal waters at Okmok Volcano, Alaska
Potential for increased hydrothermal arsenic flux during volcanic unrest: Implications for California water supply
Hydraulic, geochemical, and thermal monitoring of an aquifer system in the vicinity of Mammoth Lakes, Mono County, California, 2015–17
Rate of magma supply beneath Mammoth Mountain, California based on helium isotopes and CO2 emissions
Hot water in the Long Valley Caldera—The benefits and hazards of this large natural resource
Evidence for degassing of fresh magma during the 2004-2008 eruption of Mount St. Helens: Subtle signals from the hydrothermal system
The saltiest springs in the Sierra Nevada, California
Groundwater resources of the Devils Postpile National Monument—Current conditions and future vulnerabilities
The chemistry and isotopic composition of waters in the low-enthalpy geothermal system of Cimino-Vico Volcanic District, Italy
Experimental studies and model analysis of noble gas fractionation in porous media
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
Chemical and isotopic data on gases and waters for thermal and non-thermal features across Yellowstone National Park (2003-2015)
Fumarole gas geochemistry and tree-ring radiocarbon data at Mammoth Mountain, California (1989-2016)
Geochemistry and fluxes of gases from hydrothermal features at Newberry Volcano, Oregon, USA
Groundwater dynamics at Kīlauea Volcano and vicinity, Hawaiʻi
A post-eruption study of gases and thermal waters at Okmok Volcano, Alaska
Potential for increased hydrothermal arsenic flux during volcanic unrest: Implications for California water supply
Hydraulic, geochemical, and thermal monitoring of an aquifer system in the vicinity of Mammoth Lakes, Mono County, California, 2015–17
Rate of magma supply beneath Mammoth Mountain, California based on helium isotopes and CO2 emissions
Hot water in the Long Valley Caldera—The benefits and hazards of this large natural resource
Evidence for degassing of fresh magma during the 2004-2008 eruption of Mount St. Helens: Subtle signals from the hydrothermal system
The saltiest springs in the Sierra Nevada, California
Groundwater resources of the Devils Postpile National Monument—Current conditions and future vulnerabilities
The chemistry and isotopic composition of waters in the low-enthalpy geothermal system of Cimino-Vico Volcanic District, Italy
Experimental studies and model analysis of noble gas fractionation in porous media
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.