Michelle L. Coombs, Ph.D.
Michelle Coombs is a Research Geologist with the U.S. Geological Survey Volcanic Science Center. She served as Scientist-in-Charge of the Alaska Volcano Observatory from 2016-2023. In this position, Dr. Coombs leads eruption responses, oversees expansion and modernization of volcano monitoring techniques, and guides applied and fundamental research on a host of problems related to volcanology.
Professional Experience
2016–2023: Scientist-in-Charge, Alaska Volcano Observatory, Volcano Science Center, U.S. Geological Survey, Anchorage, AK
2004–Present: Research Geologist, Alaska Volcano Observatory
2001–2004: Research Geologist, Volcano Hazards Team, U.S. Geological Survey, Menlo Park CA
OTHER PROFESSIONAL ACTIVITIES
Affiliate faculty, University of Alaska Fairbanks
CONVERSE Steering Committee member, 2020–present
Member of AGU student awards committee, 2011–2015
Associate Editor, Bulletin of Volcanology, 2013–2016
Editorial board, Journal of Volcanology and Geothermal Research, 2007–2018
Co-editor for 28-chapter USGS Professional Paper 1769, The 2006 eruption of Augustine Volcano, Alaska, 2010
Co-editor for Journal of Volcanology and Geothermal Research special issue on Growth and collapse of Hawaiian volcanoes, 2006
Education and Certifications
Williams College, BA Geology, 1994
University of Alaska Fairbanks, PhD Geology, 2001
Affiliations and Memberships*
American Geophysical Union, 1996–present
Geological Society of America, 2001–present (elected Fellow in 2015)
International Assoc. of Volcanology and Chemistry of the Earth’s Interior, 1999–present
Science and Products
Amphibole reaction rims as a record of pre-eruptive magmatic heating: An experimental approach
Significance of a near-source tephra-stratigraphic sequence to the eruptive history of Hayes Volcano, south-central Alaska
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
Constructing a reference tephrochronology for Augustine Volcano, Alaska
Volcano–ice interactions precursory to the 2009 eruption of Redoubt Volcano, Alaska
High-resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption of Redoubt Volcano, Alaska
Pre-eruptive magmatic conditions at Augustine Volcano, Alaska, 2006: Evidence from amphibole geochemistry and textures
Andesites of the 2009 eruption of Redoubt Volcano, Alaska
Geology and 40Ar/39Ar geochronology of the medium- to high-K Tanaga volcanic cluster, western Aleutians
The 2009 eruption of Redoubt Volcano, Alaska
Using rocks to reveal the inner workings of magma chambers below volcanoes in Alaska’s National Parks
Characterizing pyroclastic-flow interactions with snow and water using environmental magnetism at Augustine Volcano: Chapter 11 in The 2006 eruption of Augustine Volcano, Alaska
Science and Products
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Filter Total Items: 70
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 reaction riAuthorsS. H. De Angelis, J. Larsen, Michelle L. Coombs, A. Dunn, Leslie A. HaydenSignificance 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 (<10 cm) tephra-fall deposits are dacitic in whole rock composition and contain high proportions of amphibole to pyroxene and minor biotite and broadly correlate to Hayes tephra set H defined by earlieAuthorsKristi L. Wallace, Michelle L. Coombs, Leslie A. Hayden, Christopher F. WaythomasCogenetic 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 at ∼26 ka aAuthorsMichelle L. Coombs, Jorge A. VazquezConstructing 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 reference stuAuthorsKristi L. Wallace, Michelle L. CoombsVolcano–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 creationAuthorsHeather A. Bleick, Michelle L. Coombs, Peter F. Cervelli, Katharine F. Bull, Rick WesselsHigh-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 followed by moreAuthorsRick L. Wessels, R. Greg Vaughan, Matthew R. Patrick, Michelle L. CoombsPre-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 compositional vaAuthorsSarah De Angelis, Jessica D Larsen, Michelle L. CoombsAndesites 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. BullGeology 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 Takawangha), theAuthorsBrian R. Jicha, Michelle L. Coombs, Andrew T. Calvert, Brad S. SingerThe 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, produced andesitiAuthorsKatharine 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. WernerUsing 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 Pacific plateAuthorsMichelle L. Coombs, Charles R. BaconCharacterizing 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 near theAuthorsJames E. Beget - News
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government