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
Character, mass, distribution, and origin of tephra-fall deposits from the 2009 eruption of Redoubt Volcano, Alaska: highlighting the significance of particle aggregation Character, mass, distribution, and origin of tephra-fall deposits from the 2009 eruption of Redoubt Volcano, Alaska: highlighting the significance of particle aggregation
The 2009 eruption of Redoubt Volcano included 20 tephra-producing explosions between March 15, 2009 and April 4, 2009 (UTC). Next-Generation radar (NEXRAD) data show that plumes reached heights between 4.6 km and 19 km asl and were distributed downwind along nearly all azimuths of the volcano. Explosions lasted between 1 and 31 min based on the signal duration at a distal seismic...
Authors
Kristi L. Wallace, Michelle L Coombs, Janet R. Schaefer
High-resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption of Redoubt Volcano, Alaska High-resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption of Redoubt Volcano, Alaska
A combination of satellite and airborne high-resolution visible and thermal infrared (TIR) image data detected and measured changes at Redoubt Volcano during the 2008–2009 unrest and eruption. The TIR sensors detected persistent elevated temperatures at summit ice-melt holes as seismicity and gas emissions increased in late 2008 to March 2009. A phreatic explosion on 15 March was...
Authors
Rick L. Wessels, R. Greg Vaughan, Matthew R. Patrick, Michelle L. Coombs
Volcano–ice interactions precursory to the 2009 eruption of Redoubt Volcano, Alaska Volcano–ice interactions precursory to the 2009 eruption of Redoubt Volcano, Alaska
In late summer of 2008, after nearly 20 years of quiescence, Redoubt Volcano began to show signs of abnormal heat flow in its summit crater. In the months that followed, the excess heat triggered melting and ablation of Redoubt's glaciers, beginning at the summit and propagating to lower elevations as the unrest accelerated. A variety of morphological changes were observed, including the...
Authors
Heather A. Bleick, Michelle L. Coombs, Peter F. Cervelli, Katharine F. Bull, Rick Wessels
Andesites of the 2009 eruption of Redoubt Volcano, Alaska 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,
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
Pre-eruptive magmatic conditions at Augustine Volcano, Alaska, 2006: Evidence from amphibole geochemistry and textures Pre-eruptive magmatic conditions at Augustine Volcano, Alaska, 2006: Evidence from amphibole geochemistry and textures
Variations in the geochemistry and texture of amphibole phenocrysts erupted from Augustine Volcano in 2006 provide new insights into pre- and syn-eruptive magma storage and mixing. Amphiboles are rare but present in all magma compositions (low- to high-silica andesites) from the 3 month long eruption. Unzoned magnesiohornblende in the high- and low-silica andesites exhibit limited...
Authors
Sarah De Angelis, Jessica D Larsen, Michelle L. Coombs
Geology and 40Ar/39Ar geochronology of the medium- to high-K Tanaga volcanic cluster, western Aleutians Geology and 40Ar/39Ar geochronology of the medium- to high-K Tanaga volcanic cluster, western Aleutians
We used geologic mapping and geochemical data augmented by 40Ar/39Ar dating to establish an eruptive chronology for the Tanaga volcanic cluster in the western Aleutian arc. The Tanaga volcanic cluster is unique in comparison to other central and western Aleutian volcanoes in that it consists of three closely spaced, active, volumetrically significant edifices (Sajaka, Tanaga, and...
Authors
Brian R. Jicha, Michelle L. Coombs, Andrew T. Calvert, Brad S. Singer
Using rocks to reveal the inner workings of magma chambers below volcanoes in Alaska’s National Parks Using rocks to reveal the inner workings of magma chambers below volcanoes in Alaska’s National Parks
Alaska is one of the most vigorously volcanic regions on the planet, and Alaska’s national parks are home to many of the state’s most active volcanoes. These pose both local and more distant hazards in the form of lava and pyroclastic flows, lahars (mudflows), ash clouds, and ash fall. Alaska’s volcanoes lie along the arc of the Aleutian-Alaskan subduction zone, caused as the oceanic...
Authors
Michelle L. Coombs, Charles R. Bacon
The 2009 eruption of Redoubt Volcano, Alaska The 2009 eruption of Redoubt Volcano, Alaska
Redoubt Volcano, an ice-covered stratovolcano on the west side of Cook Inlet, erupted in March 2009 after several months of escalating unrest. The 2009 eruption of Redoubt Volcano shares many similarities with eruptions documented most recently at Redoubt in 1966–68 and 1989–90. In each case, the eruptive phase lasted several months, consisted of multiple ashproducing explosions...
Authors
Katharine F. Bull, Cheryl Cameron, Michelle L. Coombs, Angie Diefenbach, Taryn Lopez, Steve McNutt, Christina A. Neal, Allison Payne, John A. Power, David J. Schneider, William E. Scott, Seth Snedigar, Glenn Thompson, Kristi L. Wallace, Christopher F. Waythomas, Peter Webley, Cynthia A. Werner
Timing, distribution, and volume of proximal products of the 2006 eruption of Augustine Volcano: Chapter 8 in The 2006 eruption of Augustine Volcano, Alaska Timing, distribution, and volume of proximal products of the 2006 eruption of Augustine Volcano: Chapter 8 in The 2006 eruption of Augustine Volcano, Alaska
During and after the 2006 eruption of Augustine Volcano, we compiled a geologic map and chronology of new lava and flowage deposits using observational flights, oblique and aerial photography, infrared imaging, satellite data, and field investigations. After approximately 6 months of precursory activity, the explosive phase of the eruption commenced with two explosions on January 11...
Authors
Michelle L. Coombs, Katharine F. Bull, James W. Vallance, David J. Schneider, Evan E. Thoms, Rick L. Wessels, Robert G. McGimsey
Characterizing pyroclastic-flow interactions with snow and water using environmental magnetism at Augustine Volcano: Chapter 11 in The 2006 eruption of Augustine Volcano, Alaska Characterizing pyroclastic-flow interactions with snow and water using environmental magnetism at Augustine Volcano: Chapter 11 in The 2006 eruption of Augustine Volcano, Alaska
In-place measurements of environmental magnetic susceptibility of pyroclastic flows, surges and lahars emplaced during the 2006 eruption of Augustine Volcano show that primary volume magnetic susceptibilities of pyroclastic materials decreased where the flows encountered water and steam. The Rocky Point pyroclastic flow, the largest flow of the eruption sequence, encountered a small pond...
Authors
James E. Beget
Timing, distribution, and character of tephra fall from the 2005-2006 eruption of Augustine Volcano: Chaper 9 in The 2006 eruption of Augustine Volcano Timing, distribution, and character of tephra fall from the 2005-2006 eruption of Augustine Volcano: Chaper 9 in The 2006 eruption of Augustine Volcano
The 2005–6 eruption of Augustine Volcano produced tephra-fall deposits during each of four eruptive phases. Late in the precursory phase (December 2005), small phreatic explosions produced small-volume, localized, mostly nonjuvenile tephra. The greatest volume of tephra was produced during the explosive phase (January 11–28, 2006) when 13 discrete Vulcanian explosions generated ash...
Authors
Kristi L. Wallace, Christina A. Neal, Robert G. McGimsey
High-resolution satellite and airborne thermal infrared imaging of the 2006 eruption of Augustine Volcano: Chapter 22 in The 2006 eruption of Augustine Volcano, Alaska High-resolution satellite and airborne thermal infrared imaging of the 2006 eruption of Augustine Volcano: Chapter 22 in The 2006 eruption of Augustine Volcano, Alaska
Thermal infrared (TIR) images provided a timely pre- and syn-eruption record of summit changes, lava flow emplacement, and pyroclastic-flow-deposit distribution during the Alaska Volcano Observatory's (AVO) response to the 2006 eruption of Augustine Volcano. A series of images from both handheld and helicopter mounted forward looking infrared radiometers (FLIR) captured detailed views...
Authors
Rick L. Wessels, Michelle L. Coombs, David J. Schneider, Jonathan Dehn, Michael S. Ramsey
Science and Products
Filter Total Items: 79
Character, mass, distribution, and origin of tephra-fall deposits from the 2009 eruption of Redoubt Volcano, Alaska: highlighting the significance of particle aggregation Character, mass, distribution, and origin of tephra-fall deposits from the 2009 eruption of Redoubt Volcano, Alaska: highlighting the significance of particle aggregation
The 2009 eruption of Redoubt Volcano included 20 tephra-producing explosions between March 15, 2009 and April 4, 2009 (UTC). Next-Generation radar (NEXRAD) data show that plumes reached heights between 4.6 km and 19 km asl and were distributed downwind along nearly all azimuths of the volcano. Explosions lasted between 1 and 31 min based on the signal duration at a distal seismic...
Authors
Kristi L. Wallace, Michelle L Coombs, Janet R. Schaefer
High-resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption of Redoubt Volcano, Alaska High-resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption of Redoubt Volcano, Alaska
A combination of satellite and airborne high-resolution visible and thermal infrared (TIR) image data detected and measured changes at Redoubt Volcano during the 2008–2009 unrest and eruption. The TIR sensors detected persistent elevated temperatures at summit ice-melt holes as seismicity and gas emissions increased in late 2008 to March 2009. A phreatic explosion on 15 March was...
Authors
Rick L. Wessels, R. Greg Vaughan, Matthew R. Patrick, Michelle L. Coombs
Volcano–ice interactions precursory to the 2009 eruption of Redoubt Volcano, Alaska Volcano–ice interactions precursory to the 2009 eruption of Redoubt Volcano, Alaska
In late summer of 2008, after nearly 20 years of quiescence, Redoubt Volcano began to show signs of abnormal heat flow in its summit crater. In the months that followed, the excess heat triggered melting and ablation of Redoubt's glaciers, beginning at the summit and propagating to lower elevations as the unrest accelerated. A variety of morphological changes were observed, including the...
Authors
Heather A. Bleick, Michelle L. Coombs, Peter F. Cervelli, Katharine F. Bull, Rick Wessels
Andesites of the 2009 eruption of Redoubt Volcano, Alaska 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,
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
Pre-eruptive magmatic conditions at Augustine Volcano, Alaska, 2006: Evidence from amphibole geochemistry and textures Pre-eruptive magmatic conditions at Augustine Volcano, Alaska, 2006: Evidence from amphibole geochemistry and textures
Variations in the geochemistry and texture of amphibole phenocrysts erupted from Augustine Volcano in 2006 provide new insights into pre- and syn-eruptive magma storage and mixing. Amphiboles are rare but present in all magma compositions (low- to high-silica andesites) from the 3 month long eruption. Unzoned magnesiohornblende in the high- and low-silica andesites exhibit limited...
Authors
Sarah De Angelis, Jessica D Larsen, Michelle L. Coombs
Geology and 40Ar/39Ar geochronology of the medium- to high-K Tanaga volcanic cluster, western Aleutians Geology and 40Ar/39Ar geochronology of the medium- to high-K Tanaga volcanic cluster, western Aleutians
We used geologic mapping and geochemical data augmented by 40Ar/39Ar dating to establish an eruptive chronology for the Tanaga volcanic cluster in the western Aleutian arc. The Tanaga volcanic cluster is unique in comparison to other central and western Aleutian volcanoes in that it consists of three closely spaced, active, volumetrically significant edifices (Sajaka, Tanaga, and...
Authors
Brian R. Jicha, Michelle L. Coombs, Andrew T. Calvert, Brad S. Singer
Using rocks to reveal the inner workings of magma chambers below volcanoes in Alaska’s National Parks Using rocks to reveal the inner workings of magma chambers below volcanoes in Alaska’s National Parks
Alaska is one of the most vigorously volcanic regions on the planet, and Alaska’s national parks are home to many of the state’s most active volcanoes. These pose both local and more distant hazards in the form of lava and pyroclastic flows, lahars (mudflows), ash clouds, and ash fall. Alaska’s volcanoes lie along the arc of the Aleutian-Alaskan subduction zone, caused as the oceanic...
Authors
Michelle L. Coombs, Charles R. Bacon
The 2009 eruption of Redoubt Volcano, Alaska The 2009 eruption of Redoubt Volcano, Alaska
Redoubt Volcano, an ice-covered stratovolcano on the west side of Cook Inlet, erupted in March 2009 after several months of escalating unrest. The 2009 eruption of Redoubt Volcano shares many similarities with eruptions documented most recently at Redoubt in 1966–68 and 1989–90. In each case, the eruptive phase lasted several months, consisted of multiple ashproducing explosions...
Authors
Katharine F. Bull, Cheryl Cameron, Michelle L. Coombs, Angie Diefenbach, Taryn Lopez, Steve McNutt, Christina A. Neal, Allison Payne, John A. Power, David J. Schneider, William E. Scott, Seth Snedigar, Glenn Thompson, Kristi L. Wallace, Christopher F. Waythomas, Peter Webley, Cynthia A. Werner
Timing, distribution, and volume of proximal products of the 2006 eruption of Augustine Volcano: Chapter 8 in The 2006 eruption of Augustine Volcano, Alaska Timing, distribution, and volume of proximal products of the 2006 eruption of Augustine Volcano: Chapter 8 in The 2006 eruption of Augustine Volcano, Alaska
During and after the 2006 eruption of Augustine Volcano, we compiled a geologic map and chronology of new lava and flowage deposits using observational flights, oblique and aerial photography, infrared imaging, satellite data, and field investigations. After approximately 6 months of precursory activity, the explosive phase of the eruption commenced with two explosions on January 11...
Authors
Michelle L. Coombs, Katharine F. Bull, James W. Vallance, David J. Schneider, Evan E. Thoms, Rick L. Wessels, Robert G. McGimsey
Characterizing pyroclastic-flow interactions with snow and water using environmental magnetism at Augustine Volcano: Chapter 11 in The 2006 eruption of Augustine Volcano, Alaska Characterizing pyroclastic-flow interactions with snow and water using environmental magnetism at Augustine Volcano: Chapter 11 in The 2006 eruption of Augustine Volcano, Alaska
In-place measurements of environmental magnetic susceptibility of pyroclastic flows, surges and lahars emplaced during the 2006 eruption of Augustine Volcano show that primary volume magnetic susceptibilities of pyroclastic materials decreased where the flows encountered water and steam. The Rocky Point pyroclastic flow, the largest flow of the eruption sequence, encountered a small pond...
Authors
James E. Beget
Timing, distribution, and character of tephra fall from the 2005-2006 eruption of Augustine Volcano: Chaper 9 in The 2006 eruption of Augustine Volcano Timing, distribution, and character of tephra fall from the 2005-2006 eruption of Augustine Volcano: Chaper 9 in The 2006 eruption of Augustine Volcano
The 2005–6 eruption of Augustine Volcano produced tephra-fall deposits during each of four eruptive phases. Late in the precursory phase (December 2005), small phreatic explosions produced small-volume, localized, mostly nonjuvenile tephra. The greatest volume of tephra was produced during the explosive phase (January 11–28, 2006) when 13 discrete Vulcanian explosions generated ash...
Authors
Kristi L. Wallace, Christina A. Neal, Robert G. McGimsey
High-resolution satellite and airborne thermal infrared imaging of the 2006 eruption of Augustine Volcano: Chapter 22 in The 2006 eruption of Augustine Volcano, Alaska High-resolution satellite and airborne thermal infrared imaging of the 2006 eruption of Augustine Volcano: Chapter 22 in The 2006 eruption of Augustine Volcano, Alaska
Thermal infrared (TIR) images provided a timely pre- and syn-eruption record of summit changes, lava flow emplacement, and pyroclastic-flow-deposit distribution during the Alaska Volcano Observatory's (AVO) response to the 2006 eruption of Augustine Volcano. A series of images from both handheld and helicopter mounted forward looking infrared radiometers (FLIR) captured detailed views...
Authors
Rick L. Wessels, Michelle L. Coombs, David J. Schneider, Jonathan Dehn, Michael S. Ramsey