Bill Evans, PhD (Former Employee)
Science and Products
Filter Total Items: 110
Degassing Lakes Nyos and Monoun: Defusing certain disaster Degassing Lakes Nyos and Monoun: Defusing certain disaster
Since the catastrophic releases of CO2 in the 1980s, Lakes Nyos and Monoun in Cameroon experienced CO2 recharge at alarming rates of up to 80 mol/m2 per yr. Total gas pressures reached 8.3 and 15.6 bar in Monoun (2003) and Nyos (2001), respectively, resulting in gas saturation levels up to 97%. These natural hazards are distinguished by the potential for mitigation to prevent future...
Authors
G.W. Kling, William C. Evans, G. Tanyileke, M. Kusakabe, T. Ohba, Y. Yoshida, J.V. Hell
Magmatic intrusion west of Three Sisters, central Oregon, USA: The perspective from spring geochemistry Magmatic intrusion west of Three Sisters, central Oregon, USA: The perspective from spring geochemistry
A geochemical investigation of springs near Three Sisters volcanoes was conducted in response to the detection of crustal uplift west of the peaks. Dilute, low-temperature springs near the center of uplift show 3He/4He ratios ≥7RA (RA is the ratio in air), and transport in total ∼16 MW of heat and ∼180 g/s of magmatic carbon (as CO2). These anomalous conditions clearly reflect the...
Authors
William C. Evans, M.C. van Soest, Robert H. Mariner, S. Hurwitz, S. E. Ingebritsen, C.W. Wicks, M.E. Schmidt
Excess nitrogen in selected thermal and mineral springs of the Cascade Range in northern California, Oregon, and Washington: Sedimentary or volcanic in origin? Excess nitrogen in selected thermal and mineral springs of the Cascade Range in northern California, Oregon, and Washington: Sedimentary or volcanic in origin?
Anomalous N2/Ar values occur in many thermal springs and mineral springs, some volcanic fumaroles, and at least one acid-sulfate spring of the Cascade Range. Our data show that N2/Ar values are as high as 300 in gas from some of the hot springs, as high as 1650 in gas from some of the mineral springs, and as high as 2400 in gas from the acid-sulfate spring on Mt. Shasta. In contrast, gas
Authors
Robert H. Mariner, William C. Evans, T. S. Presser, L. D. White
Mantle and Crustal Sources of Carbon, Nitrogen, and Noble gases in Cascade-Range and Aleutian-Arc Volcanic gases Mantle and Crustal Sources of Carbon, Nitrogen, and Noble gases in Cascade-Range and Aleutian-Arc Volcanic gases
Here we report anhydrous chemical (CO2, H2S, N2, H2, CH4, O2, Ar, He, Ne) and isotopic (3He/4He, 40Ar/36Ar, δ13C of CO2, δ13C of CH4, δ15N) compositions of virtually airfree gas samples collected between 1994 and 1998 from 12 quiescent but potentially restless volcanoes in the Cascade Range and Aleutian Arc (CRAA). Sample sites include ≤173°C fumaroles and springs at Mount Shasta, Mount...
Authors
Robert B. Symonds, Robert J. Poreda, William C. Evans, Cathy J. Janik, Beatrice E. Ritchie
Shallow soil CO2 flow along the San Andreas and Calaveras Faults, California Shallow soil CO2 flow along the San Andreas and Calaveras Faults, California
We evaluate a comprehensive soil CO2 survey along the San Andreas fault (SAF) in Parkfield, and the Calaveras fault (CF) in Hollister, California, in the context of spatial and temporal variability, origin, and transport of CO2 in fractured terrain. CO2 efflux was measured within grids with portable instrumentation and continously with meteorological parameters at a fixed station, in...
Authors
J.L. Lewicki, William C. Evans, G.E. Hilley, M.L. Sorey, J.D. Rogie, S.L. Brantley
Scrubbing masks magmatic degassing during repose at Cascade-Range and Aleutian-Arc volcanoes Scrubbing masks magmatic degassing during repose at Cascade-Range and Aleutian-Arc volcanoes
Between 1992 and 1998, we sampled gas discharges from ≤173°C fumaroles and springs at 12 quiescent but potentially restless volcanoes in the Cascade Range and Aleutian Arc (CRAA) including Mount Shasta, Mount Hood, Mount St. Helens, Mount Rainier, Mount Baker, Augustine Volcano, Mount Griggs, Trident, Mount Mageik, Aniakchak Crater, Akutan, and Makushin. For each site, we collected and...
Authors
Robert B. Symonds, C. J. Janik, William C. Evans, B.E. Ritchie, Dale Counce, R.J. Poreda, Mark Iven
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
Degassing Lakes Nyos and Monoun: Defusing certain disaster Degassing Lakes Nyos and Monoun: Defusing certain disaster
Since the catastrophic releases of CO2 in the 1980s, Lakes Nyos and Monoun in Cameroon experienced CO2 recharge at alarming rates of up to 80 mol/m2 per yr. Total gas pressures reached 8.3 and 15.6 bar in Monoun (2003) and Nyos (2001), respectively, resulting in gas saturation levels up to 97%. These natural hazards are distinguished by the potential for mitigation to prevent future...
Authors
G.W. Kling, William C. Evans, G. Tanyileke, M. Kusakabe, T. Ohba, Y. Yoshida, J.V. Hell
Magmatic intrusion west of Three Sisters, central Oregon, USA: The perspective from spring geochemistry Magmatic intrusion west of Three Sisters, central Oregon, USA: The perspective from spring geochemistry
A geochemical investigation of springs near Three Sisters volcanoes was conducted in response to the detection of crustal uplift west of the peaks. Dilute, low-temperature springs near the center of uplift show 3He/4He ratios ≥7RA (RA is the ratio in air), and transport in total ∼16 MW of heat and ∼180 g/s of magmatic carbon (as CO2). These anomalous conditions clearly reflect the...
Authors
William C. Evans, M.C. van Soest, Robert H. Mariner, S. Hurwitz, S. E. Ingebritsen, C.W. Wicks, M.E. Schmidt
Excess nitrogen in selected thermal and mineral springs of the Cascade Range in northern California, Oregon, and Washington: Sedimentary or volcanic in origin? Excess nitrogen in selected thermal and mineral springs of the Cascade Range in northern California, Oregon, and Washington: Sedimentary or volcanic in origin?
Anomalous N2/Ar values occur in many thermal springs and mineral springs, some volcanic fumaroles, and at least one acid-sulfate spring of the Cascade Range. Our data show that N2/Ar values are as high as 300 in gas from some of the hot springs, as high as 1650 in gas from some of the mineral springs, and as high as 2400 in gas from the acid-sulfate spring on Mt. Shasta. In contrast, gas
Authors
Robert H. Mariner, William C. Evans, T. S. Presser, L. D. White
Mantle and Crustal Sources of Carbon, Nitrogen, and Noble gases in Cascade-Range and Aleutian-Arc Volcanic gases Mantle and Crustal Sources of Carbon, Nitrogen, and Noble gases in Cascade-Range and Aleutian-Arc Volcanic gases
Here we report anhydrous chemical (CO2, H2S, N2, H2, CH4, O2, Ar, He, Ne) and isotopic (3He/4He, 40Ar/36Ar, δ13C of CO2, δ13C of CH4, δ15N) compositions of virtually airfree gas samples collected between 1994 and 1998 from 12 quiescent but potentially restless volcanoes in the Cascade Range and Aleutian Arc (CRAA). Sample sites include ≤173°C fumaroles and springs at Mount Shasta, Mount...
Authors
Robert B. Symonds, Robert J. Poreda, William C. Evans, Cathy J. Janik, Beatrice E. Ritchie
Shallow soil CO2 flow along the San Andreas and Calaveras Faults, California Shallow soil CO2 flow along the San Andreas and Calaveras Faults, California
We evaluate a comprehensive soil CO2 survey along the San Andreas fault (SAF) in Parkfield, and the Calaveras fault (CF) in Hollister, California, in the context of spatial and temporal variability, origin, and transport of CO2 in fractured terrain. CO2 efflux was measured within grids with portable instrumentation and continously with meteorological parameters at a fixed station, in...
Authors
J.L. Lewicki, William C. Evans, G.E. Hilley, M.L. Sorey, J.D. Rogie, S.L. Brantley
Scrubbing masks magmatic degassing during repose at Cascade-Range and Aleutian-Arc volcanoes Scrubbing masks magmatic degassing during repose at Cascade-Range and Aleutian-Arc volcanoes
Between 1992 and 1998, we sampled gas discharges from ≤173°C fumaroles and springs at 12 quiescent but potentially restless volcanoes in the Cascade Range and Aleutian Arc (CRAA) including Mount Shasta, Mount Hood, Mount St. Helens, Mount Rainier, Mount Baker, Augustine Volcano, Mount Griggs, Trident, Mount Mageik, Aniakchak Crater, Akutan, and Makushin. For each site, we collected and...
Authors
Robert B. Symonds, C. J. Janik, William C. Evans, B.E. Ritchie, Dale Counce, R.J. Poreda, Mark Iven
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.