Thomas Winslow Sisson, PhD
I am a research geologist with the USGS Volcano Science Center. I have spent many years working on the geologic history and volcano hazards of Mount Rainier. My research interests include experimental petrology and volatile solubility of magmas.
Education and Certifications
Ph.D. Massachusetts Institute of Technology
M.S. UC Santa Barbara
B.S. Stanford University
Science and Products
Filter Total Items: 48
Timescales of magmatic differentiation from alkali basalt to trachyte within the Harrat Rahat volcanic field, Kingdom of Saudi Arabia
A fundamental goal of igneous petrology is to quantify the duration of time required to produce evolved magmas following influx of basalt into the crust. However, in many cases, complex field relations and/or the presence of a long-lived magmatic system make it difficult to assess how basaltic inputs relate to more evolved magmas, therefore, precluding calculation of meaningful timescales. Here, w
Authors
Mark E. Stelten, Drew T. Downs, Hannah R. Dietterich, Gail A. Mahood, Andrew T. Calvert, Thomas W. Sisson, Hani M. Zahran, Jamal Shawali
Probing magma reservoirs to improve volcano forecasts
When it comes to forecasting eruptions, volcano observatories rely mostly on real-time signals from earthquakes, ground deformation, and gas discharge, combined with probabilistic assessments based on past behavior [Sparks and Cashman, 2017]. There is comparatively less reliance on geophysical and petrological understanding of subsurface magma reservoirs.
Authors
Jacob B. Lowenstern, Thomas W. Sisson, Shaul Hurwitz
Reducing risk where tectonic plates collide—U.S. Geological Survey subduction zone science plan
The U.S. Geological Survey (USGS) serves the Nation by providing reliable scientific information and tools to build resilience in communities exposed to subduction zone earthquakes, tsunamis, landslides, and volcanic eruptions. Improving the application of USGS science to successfully reduce risk from these events relies on whole community efforts, with continuing partnerships among scientists and
Authors
Joan S. Gomberg, K. A. Ludwig, Barbara Bekins, Thomas M. Brocher, John Brock, Daniel S. Brothers, Jason D. Chaytor, Arthur Frankel, Eric L. Geist, Matthew M. Haney, Stephen H. Hickman, William S. Leith, Evelyn A. Roeloffs, William H. Schulz, Thomas W. Sisson, Kristi L. Wallace, Janet Watt, Anne M. Wein
Voluminous arc dacites as amphibole reaction-boundary liquids
Dacites dominate the large-volume, explosive eruptions in magmatic arcs, and compositionally similar granodiorites and tonalites constitute the bulk of convergent margin batholiths. Shallow, pre-eruptive storage conditions are well known for many dacitic arc magmas through melt inclusions, Fe–Ti oxides, and experiments, but their potential origins deeper in the crust are not well determined. Accor
Authors
Dawnika Blatter, Thomas W. Sisson, William B. Hankins
Quantifying gas emissions from the 946 CE Millennium Eruption of Paektu volcano, Democratic People's Republic of Korea/China
Paektu volcano (Changbaishan) is a rhyolitic caldera that straddles the border between the Democratic People's Republic of Korea (DPRK) and China. Its most recent large eruption was the Millennium Eruption (ME; 23 km3 DRE) circa 946 CE, which resulted in the release of copious magmatic volatiles (H2O, CO2, sulfur, and halogens). Accurate quantification of volatile yield and composition is critical
Authors
Kayla Iacovino, Kim Ju-Song, Thomas W. Sisson, Jacob B. Lowenstern, Ri Ku-Hun, Jang Jong-Nam, Song Kun-Ho, Ham Song-Hwan, Clive Oppenheimer, James O.S. Hammond, Amy Donovan, Kosima Weber-Liu, Ryu Kum-Ran
Aluminosilicate melts and glasses at 1 to 3 GPa: Temperature and pressure effects on recovered structural and density changes
In the pressure range in the Earth’s mantle where many basaltic magmas are generated (1 to 3 GPa) (Stolper et al. 1981), increases in the coordination numbers of the network-forming cations in aluminosilicate melts have generally been considered to be minor, although effects on silicon and particularly on aluminum coordination in non-bridging oxygen-rich glasses from the higher, 5 to 12 GPa range,
Authors
S Bista, Jonathan Stebbins, William B. Hankins, Thomas W. Sisson
Petrologic insights into basaltic volcanism at historically active Hawaiian volcanoes
Study of the petrology of Hawaiian volcanoes, in particular the historically active volcanoes on the Island of Hawai‘i, has long been of worldwide scientific interest. When Dr. Thomas A. Jaggar, Jr., established the Hawaiian Volcano Observatory (HVO) in 1912, detailed observations on basaltic activity at Kīlauea and Mauna Loa volcanoes increased dramatically. The period from 1912 to 1958 saw a gra
Authors
Rosalind T. Helz, David A. Clague, Thomas W. Sisson, Carl R. Thornber
Crystallization of oxidized, moderately hydrous arc basalt at mid- to lower-crustal pressures: Implications for andesite genesis
This study focuses on the production of convergent margin calc-alkaline andesites by crystallization–differentiation of basaltic magmas in the lower to middle crust. Previous experimental studies show that dry, reduced, subalkaline basalts differentiate to tholeiitic (high Fe/Mg) daughter liquids, but the influences of H2O and oxidation on differentiation are less well established. Accordingly, we
Authors
Dawnika L. Blatter, Thomas W. Sisson, W. Ben Hankins
Petrogenesis of Mount Rainier andesite: Magma flux and geologic controls on the contrasting differentiation styles at stratovolcanoes of the southern Washington Cascades
Quaternary Mount Rainier (Washington, USA) of the Cascades magmatic arc consists of porphyritic calc-alkaline andesites and subordinate dacites, with common evidence for mingling and mixing with less evolved magmas encompassing andesites, basaltic andesites, and rarely, basalts. Basaltic andesites and amphibole andesites (spessartites) that erupted from vents at the north foot of the volcano repre
Authors
Thomas W. Sisson, V. J. M. Salters, P.B. Larson
Geologic map of southwestern Sequoia National Park, Tulare County, California
This map shows the geology of 675 km2 (260 mi2) on the west slope of the Sierra Nevada, California, mainly in Sequoia National Park and Sequoia National Forest. It was produced by the U.S. Geological Survey (USGS) at the request of the National Park Service to complete the geologic map coverage of Kings Canyon and Sequoia National Parks. The area includes the Mineral King 15’ topographic quadrangl
Authors
Thomas W. Sisson, James G. Moore
Andesites of the 2009 eruption of Redoubt Volcano, Alaska
Crystal-rich andesites that erupted from Redoubt Volcano in 2009 range from 57.5 to 62.5 wt.% SiO2 and have phenocryst and phenocryst-melt relations consistent with staging in the upper crust. Early explosive products are low-silica andesites (LSA, < 58 wt.% SiO2) that ascended from deeper crustal levels during or before the 6 months of precursory activity, but a broad subsequent succession to mor
Authors
Michelle L. Coombs, Thomas W. Sisson, Heather A. Bleick, Sarah M. Henton, Christopher J. Nye, Allison Payne, Cheryl E. Cameron, Jessica F. Larsen, Kristi L. Wallace, Katharine F. Bull
Sixty thousand years of magmatic volatile history before the caldera-forming eruption of Mount Mazama, Crater Lake, Oregon
The well-documented eruptive history of Mount Mazama, Oregon, provides an excellent opportunity to use pre-eruptive volatile concentrations to study the growth of an explosive silicic magmatic system. Melt inclusions (MI) hosted in pyroxene and plagioclase crystals from eight dacitic–rhyodacitic eruptive deposits (71–7.7 ka) were analyzed to determine variations in volatile-element concentrations
Authors
Heather M. Wright, Charles R. Bacon, Jorge A. Vazquez, Thomas W. Sisson
Science and Products
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Filter Total Items: 48
Timescales of magmatic differentiation from alkali basalt to trachyte within the Harrat Rahat volcanic field, Kingdom of Saudi Arabia
A fundamental goal of igneous petrology is to quantify the duration of time required to produce evolved magmas following influx of basalt into the crust. However, in many cases, complex field relations and/or the presence of a long-lived magmatic system make it difficult to assess how basaltic inputs relate to more evolved magmas, therefore, precluding calculation of meaningful timescales. Here, wAuthorsMark E. Stelten, Drew T. Downs, Hannah R. Dietterich, Gail A. Mahood, Andrew T. Calvert, Thomas W. Sisson, Hani M. Zahran, Jamal ShawaliProbing magma reservoirs to improve volcano forecasts
When it comes to forecasting eruptions, volcano observatories rely mostly on real-time signals from earthquakes, ground deformation, and gas discharge, combined with probabilistic assessments based on past behavior [Sparks and Cashman, 2017]. There is comparatively less reliance on geophysical and petrological understanding of subsurface magma reservoirs.AuthorsJacob B. Lowenstern, Thomas W. Sisson, Shaul HurwitzReducing risk where tectonic plates collide—U.S. Geological Survey subduction zone science plan
The U.S. Geological Survey (USGS) serves the Nation by providing reliable scientific information and tools to build resilience in communities exposed to subduction zone earthquakes, tsunamis, landslides, and volcanic eruptions. Improving the application of USGS science to successfully reduce risk from these events relies on whole community efforts, with continuing partnerships among scientists andAuthorsJoan S. Gomberg, K. A. Ludwig, Barbara Bekins, Thomas M. Brocher, John Brock, Daniel S. Brothers, Jason D. Chaytor, Arthur Frankel, Eric L. Geist, Matthew M. Haney, Stephen H. Hickman, William S. Leith, Evelyn A. Roeloffs, William H. Schulz, Thomas W. Sisson, Kristi L. Wallace, Janet Watt, Anne M. WeinVoluminous arc dacites as amphibole reaction-boundary liquids
Dacites dominate the large-volume, explosive eruptions in magmatic arcs, and compositionally similar granodiorites and tonalites constitute the bulk of convergent margin batholiths. Shallow, pre-eruptive storage conditions are well known for many dacitic arc magmas through melt inclusions, Fe–Ti oxides, and experiments, but their potential origins deeper in the crust are not well determined. AccorAuthorsDawnika Blatter, Thomas W. Sisson, William B. HankinsQuantifying gas emissions from the 946 CE Millennium Eruption of Paektu volcano, Democratic People's Republic of Korea/China
Paektu volcano (Changbaishan) is a rhyolitic caldera that straddles the border between the Democratic People's Republic of Korea (DPRK) and China. Its most recent large eruption was the Millennium Eruption (ME; 23 km3 DRE) circa 946 CE, which resulted in the release of copious magmatic volatiles (H2O, CO2, sulfur, and halogens). Accurate quantification of volatile yield and composition is criticalAuthorsKayla Iacovino, Kim Ju-Song, Thomas W. Sisson, Jacob B. Lowenstern, Ri Ku-Hun, Jang Jong-Nam, Song Kun-Ho, Ham Song-Hwan, Clive Oppenheimer, James O.S. Hammond, Amy Donovan, Kosima Weber-Liu, Ryu Kum-RanAluminosilicate melts and glasses at 1 to 3 GPa: Temperature and pressure effects on recovered structural and density changes
In the pressure range in the Earth’s mantle where many basaltic magmas are generated (1 to 3 GPa) (Stolper et al. 1981), increases in the coordination numbers of the network-forming cations in aluminosilicate melts have generally been considered to be minor, although effects on silicon and particularly on aluminum coordination in non-bridging oxygen-rich glasses from the higher, 5 to 12 GPa range,AuthorsS Bista, Jonathan Stebbins, William B. Hankins, Thomas W. SissonPetrologic insights into basaltic volcanism at historically active Hawaiian volcanoes
Study of the petrology of Hawaiian volcanoes, in particular the historically active volcanoes on the Island of Hawai‘i, has long been of worldwide scientific interest. When Dr. Thomas A. Jaggar, Jr., established the Hawaiian Volcano Observatory (HVO) in 1912, detailed observations on basaltic activity at Kīlauea and Mauna Loa volcanoes increased dramatically. The period from 1912 to 1958 saw a graAuthorsRosalind T. Helz, David A. Clague, Thomas W. Sisson, Carl R. ThornberCrystallization of oxidized, moderately hydrous arc basalt at mid- to lower-crustal pressures: Implications for andesite genesis
This study focuses on the production of convergent margin calc-alkaline andesites by crystallization–differentiation of basaltic magmas in the lower to middle crust. Previous experimental studies show that dry, reduced, subalkaline basalts differentiate to tholeiitic (high Fe/Mg) daughter liquids, but the influences of H2O and oxidation on differentiation are less well established. Accordingly, weAuthorsDawnika L. Blatter, Thomas W. Sisson, W. Ben HankinsPetrogenesis of Mount Rainier andesite: Magma flux and geologic controls on the contrasting differentiation styles at stratovolcanoes of the southern Washington Cascades
Quaternary Mount Rainier (Washington, USA) of the Cascades magmatic arc consists of porphyritic calc-alkaline andesites and subordinate dacites, with common evidence for mingling and mixing with less evolved magmas encompassing andesites, basaltic andesites, and rarely, basalts. Basaltic andesites and amphibole andesites (spessartites) that erupted from vents at the north foot of the volcano repreAuthorsThomas W. Sisson, V. J. M. Salters, P.B. LarsonGeologic map of southwestern Sequoia National Park, Tulare County, California
This map shows the geology of 675 km2 (260 mi2) on the west slope of the Sierra Nevada, California, mainly in Sequoia National Park and Sequoia National Forest. It was produced by the U.S. Geological Survey (USGS) at the request of the National Park Service to complete the geologic map coverage of Kings Canyon and Sequoia National Parks. The area includes the Mineral King 15’ topographic quadranglAuthorsThomas W. Sisson, James G. MooreAndesites of the 2009 eruption of Redoubt Volcano, Alaska
Crystal-rich andesites that erupted from Redoubt Volcano in 2009 range from 57.5 to 62.5 wt.% SiO2 and have phenocryst and phenocryst-melt relations consistent with staging in the upper crust. Early explosive products are low-silica andesites (LSA, < 58 wt.% SiO2) that ascended from deeper crustal levels during or before the 6 months of precursory activity, but a broad subsequent succession to morAuthorsMichelle L. Coombs, Thomas W. Sisson, Heather A. Bleick, Sarah M. Henton, Christopher J. Nye, Allison Payne, Cheryl E. Cameron, Jessica F. Larsen, Kristi L. Wallace, Katharine F. BullSixty thousand years of magmatic volatile history before the caldera-forming eruption of Mount Mazama, Crater Lake, Oregon
The well-documented eruptive history of Mount Mazama, Oregon, provides an excellent opportunity to use pre-eruptive volatile concentrations to study the growth of an explosive silicic magmatic system. Melt inclusions (MI) hosted in pyroxene and plagioclase crystals from eight dacitic–rhyodacitic eruptive deposits (71–7.7 ka) were analyzed to determine variations in volatile-element concentrationsAuthorsHeather M. Wright, Charles R. Bacon, Jorge A. Vazquez, Thomas W. Sisson