Michelle L. Coombs, Ph.D.
Michelle Coombs is a Supervisory Research Geologist with the U.S. Geological Survey Volcanic Science Center. At the Alaska Volcano Observatory, she works on a wide variety of topics related to active volcanism, volcano geology, and volcanic hazards. She also serves as chief of the Volcano Hazards Assessment Project.
Professional Experience
2023–present: Supervisory Research Geologist, Alaska Volcano Observatory, Volcano Science Center, U.S. Geological Survey, Anchorage, AK
2016–2023: Scientist-in-Charge, Alaska Volcano Observatory
2004–2016: Research Geologist, Alaska Volcano Observatory
2001–2004: Research Geologist, Volcano Hazards Team, U.S. Geological Survey, Menlo Park CA
Education and Certifications
B.A., Geology, Williams College, 1994
Ph.D., Geology, University of Alaska Fairbanks, 2001
Science and Products
Filter Total Items: 79
Phase equilibrium of a high-SiO2, andesite at fO2 = RRO: Implications for Augustine volcano and other high-fO2 arc andesites Phase equilibrium of a high-SiO2, andesite at fO2 = RRO: Implications for Augustine volcano and other high-fO2 arc andesites
Understanding the impact of magmatic plumbing systems on explosive volcanic activity is important for hazard management. This study describes phase equilibria experiments using a high-silica andesite (HSA; SiO2 = 62.5 wt%) from the 2006 eruption of Augustine Volcano, Alaska. Experiments were conducted under H2O saturated conditions, f02f02 = RRO (Re–ReO2 or ~ Ni–NiO + 2), at pressures of...
Authors
Sarah H. De Angelis, Jessica F. Larsen, Michelle L. Coombs, James E. P. Utley, Andrew P. Dunn
Petrology of the 2016–2017 eruption of Bogoslof Island Petrology of the 2016–2017 eruption of Bogoslof Island
The 2016–2017 eruption of Bogoslof primarily produced crystal-rich amphibole basalts. The dominant juvenile tephra were highly microlitic with diktytaxitic vesicles, and amphiboles had large reaction rims. Both observations support a magma history of slow ascent and/or shallow stalling prior to eruption. Plagioclase-amphibole-clinopyroxene mineralogy are also suggestive of shallow magma
Authors
Matthew W. Loewen, Pavel Izbekof, Jamshid Moshrefzadeh, Michelle L. Coombs, Jessica Larsen, Nathan Graham, Michelle Harbin, Christopher F. Waythomas, Kristi L. Wallace
Overview, chronology, and impacts of the 2016–2017 eruption of Bogoslof volcano, Alaska Overview, chronology, and impacts of the 2016–2017 eruption of Bogoslof volcano, Alaska
The 2016–2017 eruption of Bogoslof volcano, a back-arc shallow submarine volcano in Alaska’s Aleutian arc, began in December 2016 and included 70 explosive events and at least two episodes of subaerial dome building. Because the volcano had no local monitoring stations during the eruption, a combination of distant seismic stations, regional infrasound sensors, lightning detection, a...
Authors
Michelle L. Coombs, Kristi L. Wallace, Cheryl Cameron, John J. Lyons, Aaron Wech, Kim M. Angeli, Peter Cervelli
On the eruption age and provenance of the Old Crow tephra On the eruption age and provenance of the Old Crow tephra
Tephrochronology is used to correlate and reconstruct geographically disparate sedimentary records of changing environment, climate, and landscape throughout geologic time. Single tephra layers represent isochronous markers across broad regions, thus accurate and precise radiometric constraints on the timing of eruption are critical to their utility. The Old Crow tephra is found...
Authors
Seth D. Burgess, Matthew Coble, Jorge A. Vazquez, Michelle L. Coombs, Kristi L. Wallace
The 2018 rift eruption and summit collapse of Kilauea Volcano The 2018 rift eruption and summit collapse of Kilauea Volcano
In 2018, Kīlauea Volcano experienced its largest lower East Rift Zone (LERZ) eruption and caldera collapse in at least 200 years. After collapse of the Pu'u 'Ō'ō vent on 30 April, magma propagated downrift. Eruptive fissures opened in the LERZ on 3 May, eventually extending ~6.8 km. A 4 May earthquake (M6.9) produced ~5 m of fault slip. Lava erupted at rates exceeding 100 m3/s...
Authors
Christina A. Neal, Steven Brantley, Loren Antolik, Janet Babb, Matthew K. Burgess, Michael Cappos, Jefferson C. Chang, Sarah Conway, Liliana G. Desmither, Peter J. Dotray, Tamar Elias, Pauline Fukunaga, Steven Fuke, Ingrid A. Johanson, Kevan Kamibayashi, James P. Kauahikaua, R. Lopaka Lee, S. Pekalib, Asta Miklius, Brian Shiro, Don Swanson, Patricia A. Nadeau, Michael H. Zoeller, P. Okubo, Carolyn Parcheta, Matthew R. Patrick, William Tollett, Frank A. Trusdell, Edward F. Younger, Emily K. Montgomery-Brown, Kyle R. Anderson, Michael P. Poland, Jessica L. Ball, Joseph A. Bard, Michelle L. Coombs, Hannah R. Dietterich, Christoph Kern, Weston Thelen, Peter Cervelli, Tim R. Orr, Bruce F. Houghton, Cheryl Gansecki, Richard Hazlett, Paul R. Lundgren, Angela K. Diefenbach, Allan Lerner, Greg Waite, Peter J. Kelly, Laura E. Clor, Cynthia Werner, Katherine Mulliken, Gary B. Fisher, David Damby
Short-term forecasting and detection of explosions during the 2016–2017 eruption of Bogoslof volcano, Alaska Short-term forecasting and detection of explosions during the 2016–2017 eruption of Bogoslof volcano, Alaska
We describe a multidisciplinary approach to forecast, rapidly detect, and characterize explosive events during the 2016–2017 eruption of Bogoslof volcano, a back-arc shallow submarine volcano in Alaska’s Aleutian arc. The eruptive sequence began in December 2016 and included about 70 discrete explosive events. Because the volcano has no local monitoring stations, we used distant stations...
Authors
Michelle L. Coombs, Aaron Wech, Matthew M. Haney, John J. Lyons, David J. Schneider, Hans Schwaiger, Kristi L. Wallace, David Fee, Jeffrey T. Freymueller, Janet Schaefer, Gabrielle Tepp
Alaska Volcano Observatory alert and forecasting timeliness: 1989–2017 Alaska Volcano Observatory alert and forecasting timeliness: 1989–2017
The Alaska Volcano Observatory (AVO) monitors volcanoes in Alaska and issues notifications and warnings of volcanic unrest and eruption. We evaluate the timeliness and accuracy of eruption forecasts for 53 eruptions at 20 volcanoes, beginning with Mount Redoubt's 1989–1990 eruption. Successful forecasts are defined as those where AVO issued a formal warning before eruption onset. These...
Authors
Cheryl Cameron, Stephanie G. Prejean, Michelle L. Coombs, Kristi L. Wallace, John A. Power, Diana C. Roman
Postglacial eruptive history and geochemistry of Semisopochnoi volcano, western Aleutian Islands, Alaska Postglacial eruptive history and geochemistry of Semisopochnoi volcano, western Aleutian Islands, Alaska
Semisopochnoi Island, located in the Rat Islands group of the western Aleutian Islands and Aleutian volcanic arc, is a roughly circular island composed of scattered volcanic vents, the prominent caldera of Semisopochnoi volcano, and older, ancestral volcanic rocks. The oldest rocks on the island are gently radially dipping lavas that are the remnants of a shield volcano and of Ragged Top...
Authors
Michelle L. Coombs, Jessica F. Larsen, Christina A. Neal
Amphibole reaction rims as a record of pre-eruptive magmatic heating: An experimental approach Amphibole reaction rims as a record of pre-eruptive magmatic heating: An experimental approach
Magmatic minerals record the pre-eruptive timescales of magma ascent and mixing in crustal reservoirs and conduits. Investigations of the mineral records of magmatic processes are fundamental to our understanding of what controls eruption style, as ascent rates and magma mixing processes are well known to control and/or trigger potentially hazardous explosive eruptions. Thus, amphibole...
Authors
S. H. De Angelis, J. Larsen, Michelle L. Coombs, A. Dunn, Leslie A. Hayden
Significance of a near-source tephra-stratigraphic sequence to the eruptive history of Hayes Volcano, south-central Alaska Significance of a near-source tephra-stratigraphic sequence to the eruptive history of Hayes Volcano, south-central Alaska
Bluffs along the Hayes River valley, 31 km northeast and 40 km downstream from Hayes Volcano, reveal volcanic deposits that shed new light on its eruptive history. Three thick (>10 cm) and five thin (
Authors
Kristi L. Wallace, Michelle L. Coombs, Leslie A. Hayden, Christopher F. Waythomas
Cogenetic late Pleistocene rhyolite and cumulate diorites from Augustine Volcano revealed by SIMS 238U-230Th dating of zircon, and implications for silicic magma generation by extraction from mush Cogenetic late Pleistocene rhyolite and cumulate diorites from Augustine Volcano revealed by SIMS 238U-230Th dating of zircon, and implications for silicic magma generation by extraction from mush
Augustine Volcano, a frequently active andesitic island stratocone, erupted a late Pleistocene rhyolite pumice fall that is temporally linked through zircon geochronology to cumulate dioritic blocks brought to the surface in Augustine's 2006 eruption. Zircon from the rhyolite yield a 238U-230Th age of ∼25 ka for their unpolished rims, and their interiors yield a bimodal age populations...
Authors
Michelle L. Coombs, Jorge A. Vazquez
Constructing a reference tephrochronology for Augustine Volcano, Alaska Constructing a reference tephrochronology for Augustine Volcano, Alaska
Augustine Volcano is the most historically active volcano in Alaska's populous Cook Inlet region. Past on-island work on pre-historic tephra deposits mainly focused on using tephra layers as markers to help distinguish among prevalent debris-avalanche deposits on the island (Waitt and Beget, 2009, USGS Prof Paper 1762), or as source material for petrogenetic studies. No comprehensive...
Authors
Kristi L. Wallace, Michelle L. Coombs
Science and Products
Filter Total Items: 79
Phase equilibrium of a high-SiO2, andesite at fO2 = RRO: Implications for Augustine volcano and other high-fO2 arc andesites Phase equilibrium of a high-SiO2, andesite at fO2 = RRO: Implications for Augustine volcano and other high-fO2 arc andesites
Understanding the impact of magmatic plumbing systems on explosive volcanic activity is important for hazard management. This study describes phase equilibria experiments using a high-silica andesite (HSA; SiO2 = 62.5 wt%) from the 2006 eruption of Augustine Volcano, Alaska. Experiments were conducted under H2O saturated conditions, f02f02 = RRO (Re–ReO2 or ~ Ni–NiO + 2), at pressures of...
Authors
Sarah H. De Angelis, Jessica F. Larsen, Michelle L. Coombs, James E. P. Utley, Andrew P. Dunn
Petrology of the 2016–2017 eruption of Bogoslof Island Petrology of the 2016–2017 eruption of Bogoslof Island
The 2016–2017 eruption of Bogoslof primarily produced crystal-rich amphibole basalts. The dominant juvenile tephra were highly microlitic with diktytaxitic vesicles, and amphiboles had large reaction rims. Both observations support a magma history of slow ascent and/or shallow stalling prior to eruption. Plagioclase-amphibole-clinopyroxene mineralogy are also suggestive of shallow magma
Authors
Matthew W. Loewen, Pavel Izbekof, Jamshid Moshrefzadeh, Michelle L. Coombs, Jessica Larsen, Nathan Graham, Michelle Harbin, Christopher F. Waythomas, Kristi L. Wallace
Overview, chronology, and impacts of the 2016–2017 eruption of Bogoslof volcano, Alaska Overview, chronology, and impacts of the 2016–2017 eruption of Bogoslof volcano, Alaska
The 2016–2017 eruption of Bogoslof volcano, a back-arc shallow submarine volcano in Alaska’s Aleutian arc, began in December 2016 and included 70 explosive events and at least two episodes of subaerial dome building. Because the volcano had no local monitoring stations during the eruption, a combination of distant seismic stations, regional infrasound sensors, lightning detection, a...
Authors
Michelle L. Coombs, Kristi L. Wallace, Cheryl Cameron, John J. Lyons, Aaron Wech, Kim M. Angeli, Peter Cervelli
On the eruption age and provenance of the Old Crow tephra On the eruption age and provenance of the Old Crow tephra
Tephrochronology is used to correlate and reconstruct geographically disparate sedimentary records of changing environment, climate, and landscape throughout geologic time. Single tephra layers represent isochronous markers across broad regions, thus accurate and precise radiometric constraints on the timing of eruption are critical to their utility. The Old Crow tephra is found...
Authors
Seth D. Burgess, Matthew Coble, Jorge A. Vazquez, Michelle L. Coombs, Kristi L. Wallace
The 2018 rift eruption and summit collapse of Kilauea Volcano The 2018 rift eruption and summit collapse of Kilauea Volcano
In 2018, Kīlauea Volcano experienced its largest lower East Rift Zone (LERZ) eruption and caldera collapse in at least 200 years. After collapse of the Pu'u 'Ō'ō vent on 30 April, magma propagated downrift. Eruptive fissures opened in the LERZ on 3 May, eventually extending ~6.8 km. A 4 May earthquake (M6.9) produced ~5 m of fault slip. Lava erupted at rates exceeding 100 m3/s...
Authors
Christina A. Neal, Steven Brantley, Loren Antolik, Janet Babb, Matthew K. Burgess, Michael Cappos, Jefferson C. Chang, Sarah Conway, Liliana G. Desmither, Peter J. Dotray, Tamar Elias, Pauline Fukunaga, Steven Fuke, Ingrid A. Johanson, Kevan Kamibayashi, James P. Kauahikaua, R. Lopaka Lee, S. Pekalib, Asta Miklius, Brian Shiro, Don Swanson, Patricia A. Nadeau, Michael H. Zoeller, P. Okubo, Carolyn Parcheta, Matthew R. Patrick, William Tollett, Frank A. Trusdell, Edward F. Younger, Emily K. Montgomery-Brown, Kyle R. Anderson, Michael P. Poland, Jessica L. Ball, Joseph A. Bard, Michelle L. Coombs, Hannah R. Dietterich, Christoph Kern, Weston Thelen, Peter Cervelli, Tim R. Orr, Bruce F. Houghton, Cheryl Gansecki, Richard Hazlett, Paul R. Lundgren, Angela K. Diefenbach, Allan Lerner, Greg Waite, Peter J. Kelly, Laura E. Clor, Cynthia Werner, Katherine Mulliken, Gary B. Fisher, David Damby
Short-term forecasting and detection of explosions during the 2016–2017 eruption of Bogoslof volcano, Alaska Short-term forecasting and detection of explosions during the 2016–2017 eruption of Bogoslof volcano, Alaska
We describe a multidisciplinary approach to forecast, rapidly detect, and characterize explosive events during the 2016–2017 eruption of Bogoslof volcano, a back-arc shallow submarine volcano in Alaska’s Aleutian arc. The eruptive sequence began in December 2016 and included about 70 discrete explosive events. Because the volcano has no local monitoring stations, we used distant stations...
Authors
Michelle L. Coombs, Aaron Wech, Matthew M. Haney, John J. Lyons, David J. Schneider, Hans Schwaiger, Kristi L. Wallace, David Fee, Jeffrey T. Freymueller, Janet Schaefer, Gabrielle Tepp
Alaska Volcano Observatory alert and forecasting timeliness: 1989–2017 Alaska Volcano Observatory alert and forecasting timeliness: 1989–2017
The Alaska Volcano Observatory (AVO) monitors volcanoes in Alaska and issues notifications and warnings of volcanic unrest and eruption. We evaluate the timeliness and accuracy of eruption forecasts for 53 eruptions at 20 volcanoes, beginning with Mount Redoubt's 1989–1990 eruption. Successful forecasts are defined as those where AVO issued a formal warning before eruption onset. These...
Authors
Cheryl Cameron, Stephanie G. Prejean, Michelle L. Coombs, Kristi L. Wallace, John A. Power, Diana C. Roman
Postglacial eruptive history and geochemistry of Semisopochnoi volcano, western Aleutian Islands, Alaska Postglacial eruptive history and geochemistry of Semisopochnoi volcano, western Aleutian Islands, Alaska
Semisopochnoi Island, located in the Rat Islands group of the western Aleutian Islands and Aleutian volcanic arc, is a roughly circular island composed of scattered volcanic vents, the prominent caldera of Semisopochnoi volcano, and older, ancestral volcanic rocks. The oldest rocks on the island are gently radially dipping lavas that are the remnants of a shield volcano and of Ragged Top...
Authors
Michelle L. Coombs, Jessica F. Larsen, Christina A. Neal
Amphibole reaction rims as a record of pre-eruptive magmatic heating: An experimental approach Amphibole reaction rims as a record of pre-eruptive magmatic heating: An experimental approach
Magmatic minerals record the pre-eruptive timescales of magma ascent and mixing in crustal reservoirs and conduits. Investigations of the mineral records of magmatic processes are fundamental to our understanding of what controls eruption style, as ascent rates and magma mixing processes are well known to control and/or trigger potentially hazardous explosive eruptions. Thus, amphibole...
Authors
S. H. De Angelis, J. Larsen, Michelle L. Coombs, A. Dunn, Leslie A. Hayden
Significance of a near-source tephra-stratigraphic sequence to the eruptive history of Hayes Volcano, south-central Alaska Significance of a near-source tephra-stratigraphic sequence to the eruptive history of Hayes Volcano, south-central Alaska
Bluffs along the Hayes River valley, 31 km northeast and 40 km downstream from Hayes Volcano, reveal volcanic deposits that shed new light on its eruptive history. Three thick (>10 cm) and five thin (
Authors
Kristi L. Wallace, Michelle L. Coombs, Leslie A. Hayden, Christopher F. Waythomas
Cogenetic late Pleistocene rhyolite and cumulate diorites from Augustine Volcano revealed by SIMS 238U-230Th dating of zircon, and implications for silicic magma generation by extraction from mush Cogenetic late Pleistocene rhyolite and cumulate diorites from Augustine Volcano revealed by SIMS 238U-230Th dating of zircon, and implications for silicic magma generation by extraction from mush
Augustine Volcano, a frequently active andesitic island stratocone, erupted a late Pleistocene rhyolite pumice fall that is temporally linked through zircon geochronology to cumulate dioritic blocks brought to the surface in Augustine's 2006 eruption. Zircon from the rhyolite yield a 238U-230Th age of ∼25 ka for their unpolished rims, and their interiors yield a bimodal age populations...
Authors
Michelle L. Coombs, Jorge A. Vazquez
Constructing a reference tephrochronology for Augustine Volcano, Alaska Constructing a reference tephrochronology for Augustine Volcano, Alaska
Augustine Volcano is the most historically active volcano in Alaska's populous Cook Inlet region. Past on-island work on pre-historic tephra deposits mainly focused on using tephra layers as markers to help distinguish among prevalent debris-avalanche deposits on the island (Waitt and Beget, 2009, USGS Prof Paper 1762), or as source material for petrogenetic studies. No comprehensive...
Authors
Kristi L. Wallace, Michelle L. Coombs