Michelle has been a Research Geologist for USGS-AVO in Anchorage since 2004. Her work includes research on a wide variety of topics in geology, petrology, and geochemistry, as well as geologic mapping and hazards assessment. Recent and current research interests include (1) timing and generation of explosive silicic eruptions at Alaskan volcanoes, especially Augustine and Hayes; (2) refined edifice mapping and eruptive history of Akutan, Spurr, and Redoubt volcanoes; and (3) combining petrologic study with detailed eruption chronologies to elucidate processes of magma generation and eruption triggering at dome-forming volcanoes such as Redoubt and Augustine.
From March 2016 to May 2023, Michelle was the Scientist-in-Charge for AVO.
Prior to 2004, she worked for the USGS in Menlo Park, CA, where her research focused on the geochemistry, petrology, and submarine geology of Hawaiian volcanoes.
Andrys, J. L., Coombs, M. L., Cottrell, E., Kelley, K. A., Waters, L. E., and Jicha, B., 2024, Bulk compositions of western Aleutians tephras and lavas collected during leg 3 of the NSF GeoPRISMS shared platform for Aleutians research, Version 1.0: Interdisciplinary Earth Data Alliance (IEDA). https://doi.org/10.60520/IEDA/113465.
Coombs, M.L., Cameron, C.E., Dietterich, H.R., Boyce, E.S., Wech, A.G., Grapenthin, R., Wallace, K.L., Parker, T., Lopez, T., Crass, S., Fee, D., Haney, M.M., Ketner, D., Loewen, M.W., Lyons, J.J., Nakai, J.S., Power, J.A., Botnick, S., Brewster, I., Enders, M.L., Harmon, D., Kelly, P.J., and Randall, M., 2024, From field station to forecast: managing data at the Alaska Volcano Observatory: Bulletin of Volcanology v. 86, 79. https://doi.org/10.1007/s00445-024-01766-0
Loewen, M.W., Wallace, Kristi, Coombs, M.L., and Mulliken, K.M., 2023, Tephra samples and analyses from Cook Inlet source volcanoes and Anchor Point, Alaska: Alaska Division of Geological & Geophysical Surveys Raw Data File 2023-25, 4 p. https://doi.org/10.14509/31090
Lubbers, J., Loewen, M., Wallace, K., Coombs, M., and Addison, J., 2023, Probabilistic source classification of large tephra producing eruptions using supervised machine learning - an example from the Alaska-Aleutian Arc: Geochemistry, Geophysics, Geosystems v. 24, no. 11, e2023GC011037. https://doi.org/10.1029/2023GC011037.
Benage, M.C., Wright, H.M.N., and Coombs, M.L., 2021, Eruption of compositionally heterogeneous andesites from a complex storage region during the 2006 eruption of Augustine Volcano: Bulletin of Volcanology, v. 83, n. 17, 23 p., doi:10.1007/s00445-020-01431-2.
Waters, L.E., Cottrell, Elizabeth, Coombs, M.L., and Kelley, K.A., 2021, Generation of calc-alkaline magmas during crystallization at high oxygen fugacity: an experimental and petrologic study of tephras from Buldir Volcano, western Aleutian arc, Alaska, USA: Journal of Petrology, p. 1-36, doi:10.1093/petrology/egaa104.
De Angelis, S.H., Larsen, J.F., Coombs, M.L., Utley, J.E.P., and Dunn, Andrew, 2020, Phase equilibrium of a high SiO2 andesite at fO2=RRO - Implications for Augustine Volcano and other high fO2 arc andesites: Contributions to Mineralogy and Petrology, v. 175, no. 24, 20 p., https://doi.org/10.1007/s00410-020-1663-6.
De Angelis, S.H., Larsen, J.F., Coombs, M.L., Utley, J.E.P., and Dunn, Andrew, 2020, Phase equlibrium of a high-SiO2 andesite at fO2=RRO: implications for Augustine Volcano and other high-fO2 arc andesites: Contributions to Mineralogy and Petrology, v. 175, n. 24, 21 p., doi: https://doi.org/10.1007/s00410-020-1663-6.
Coombs, M.L., and Jicha, B.R., 2020, The eruptive history, magmatic evolution, and influence of glacial ice at long-lived Akutan volcano, eastern Aleutian Islands, Alaska: GSA Bulletin, 29 p., https://doi.org/10.1130/B35667.1.
Coombs, Michelle, Wallace, Kristi, Cameron, Cheryl, Lyons, John, Wech, Aaron, Angeli, Kim, and Cervelli, Peter, 2019, Overview, chronology, and impacts of the 2016-2017 eruption of Bogoslof volcano, Alaska: Bulletin of Volcanology, v, 81, n. 62, doi:10.1007/s00445-019-1322-9.
Loewen, M.L., Izbekov, Pavel, Moshrefzadeh, Jamshid, Coombs, Michelle, Larsen, Jessica, Graham, Nathan, Harbin, Michelle, Waythomas, Christopher, and Wallace, Kristi, 2019, Petrology of the 2016-2017 eruption of Bogoslof Island, Alaska: Bulletin of Volcanology v. 81, n. 72, 20 p., doi:10.1007/s00445-019-1333-6.
Coombs, M.L., Larsen, J.F., and Neal, C.A., 2018, Postglacial eruptive history and geochemistry of Semisopochnoi volcano, western Aleutian Islands, Alaska: U.S. Geological Survey Scientific Investigations Report 2017-5150, 32 p., https://doi.org/10.3133/sir20175150.
Coombs, M.L., Wech, A.G., Haney, M.M., Lyons, J.J., Schneider, D.J., Schwaiger, H.F., Wallace, K.L., Fee, David, Freymueller, J.T., Schaefer, J.R., and Tepp, Gabrielle, 2018, Short-term forecasting and detection of explosions during the 2016-2017 eruption of Bogoslof Volcano, Alaska: Frontiers in Earth Science, v. 6, article 122, doi: 10.3389/feart.2018.00122 .
Evans, W.C., Bergfeld, D., Neal, C.A., McGimsey, R.G., Werner, C.A., Waythomas, C.F., Lewicki, J.L., Lopez, T., Mangan, M.T., Miller, T.P., Diefenbach, A., Schaefer, J., Coombs, M.L., Wang, B., Nicolaysen, K., Izbekov, P., Maharrey, Z., Huebner, M., Hunt, A.G., Fitzpatrick, J., and Freeburg, G., 2015, Aleutian Arc geothermal fluids: chemical analyses of waters and gases: U.S. Geological Survey Data release, http://dx.doi.org/10.5066/F74X55VB
De Angelis, S.H., Larsen, J., Coombs, M., Dunn, A., and Hayden, L., 2015, Amphibole reaction rims as a record of pre-eruptive magmatic heating: an experimental approach: Earth and Planetary Science Letters, v. 426, p. 235-245, doi:10.1016/j.epsl.2015.06.051
Coombs, M.L., and Vazquez, J.A., 2014, 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: Geochemistry, Geophysics, Geosystems, v. 15, 20 p., doi:10.1002/2014GC005589
Wallace, K.L., Coombs, M.L., Hayden, L.A., and Waythomas, C.F., 2014, Significance of a near-source tephra-stratigraphic sequence to the eruptive history of Hayes Volcano, south-central Alaska: U.S. Geological Survey Scientific Investigations Report 2014-5133, 32 p., available online at: http://pubs.usgs.gov/sir/2014/5133/
Coombs, M.L., Sisson, T.W., Bleick, H.A., Henton, S.M., Nye, C.J., Payne, A.L., Cameron, C.E., Larsen, J.F., Wallace, K.L., and Bull, K.F., 2013, Andesites of the 2009 eruption of Redoubt Volcano, Alaska: Journal of Volcanology and Geothermal Research, v. 259, p. 349-372, doi:10.1016/j.jvolgeores.2012.01.002
Wallace, K.L., Schaefer, J.R., and Coombs, M.L., 2013, Character, mass, distribution, and origin of tephra-fall deposits from the 2009 eruption of Redoubt Volcano, Alaska - Highlighting the significance of particle aggregation: Journal of Volcanology and Geothermal Research, v. 259, p. 145-169, doi:10.1016/j.jvolgeores.2012.09.015
Wessels, R.L., Vaughan, R.G., Patrick, M.R., and Coombs, M.L., 2013, High-resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption at Redoubt Volcano, Alaska: Journal of Volcanology and Geothermal Research, v. 259, p. 248-269, doi:10.1016/j.jvolgeores.2012.04.014
De Angelis, S.H., Larsen, Jessica, and Coombs, Michelle, 2013, Pre-eruptive magmatic conditions at Augustine Volcano, Alaska, 2006: evidence from amphibole geochemistry and textures: Journal of Petrology, v. 54, n. 9, p. 1939-1961, doi:10.1093/petrology/egt037
Bleick, H.A., Coombs, M.L., Cervelli, P.F., Bull, K.F., and Wessels, R.L., 2013, Volcano-ice interactions precursory to the 2009 eruption of Redoubt Volcano, Alaska: Journal of Volcanology and Geothermal Research, v. 259, p. 373-388, doi:10.1016/j.jvolgeores.2012.10.008
Coombs, M.L., McGimsey, R.G., and Browne, B.L., 2012, Geologic map of Mount Gareloi, Gareloi Island, Alaska: U.S. Geological Survey Scientific Investigations Map 3145, 18 p., 1 sheet, scale 1:24,000, available at http://pubs.usgs.gov/sim/3145/ .
Jicha, B.R., Coombs, M.L., Calvert, A.T., and Singer, B.S., 2012, Geology and 40Ar/39Ar geochronology of the medium- to high-K Tanaga volcanic cluster, western Aleutians: Geological Society of America Bulletin, v. 124, n. 5/6, p. 842-856, doi:10.1130/B30472.1 .
Winfree, Robert, with contributions from Bacon, C.R., Bennett, A.J., Bennington, Ninfa, Berg, E.E., Brooks, Margi, Coletti, H.A., Coombs, M.L., Fierstein, Judy, Freeburg, Gary, Frost, G.V., Haney, Matthew, Jorgenson, M.T., Miller, A.E., Moran, Seth, Murphy, Rachel, Partnow, Patricia, Paskievitch, John, Stevens, D.P., Powell, Lee, Power, John, Prejean, S.G., Schaaf, Jeanne, Sherriff, R.L., Thurber, Clifford, and Welchman, R.A., 2012, Katmai science studies: Alaska Park Science Journal, v. 11, n. 1, 96 p., available online at http://www.nps.gov/akso/nature/science/ak_park_science/volume_11_issue_1.cfm .
Schaefer, J.R., ed., 2012, The 2009 eruption of Redoubt Volcano, Alaska, with contributions by Bull, Katharine, Cameron, Cheryl, Coombs, Michelle, Diefenbach, Angie, Lopez, Taryn, McNutt, Steve, Neal, Christina, Payne, Allison, Power, John, Schneider, Dave, Scott, William, Snedigar, Seth, Thompson, Glenn, Wallace, Kristi, Waythomas, Chris, Webley, Peter, and Werner, Cynthia: Alaska Division of Geological & Geophysical Surveys Report of Investigation 2011-5, 45 p., available at http://www.dggs.alaska.gov/pubs/id/23123.
Coombs, M.L., and Bacon, C.R., 2012, Using rocks to reveal the inner workings of magma chambers below volcanoes in Alaska's National Parks: in Alaska: in Winfree, Robert (project lead), Katmai Science Studies: Alaska Park Science Journal, v. 11, n. 1, p. 26-33, available online at http://www.nps.gov/akso/nature/science/ak_park_science/volume_11_issue_1.cfm .
Coombs, Michelle, 2011, Volcano from space, in Cook Inlet volcanoes: Frontier Scientists, WonderVisions, video, available at http://frontierscientists.com/category/cook_inlet_volcanoes/
Webster, J.D., Mandeville, C.W., Goldoff, Beth, Coombs, M.L., and Tappen, Christine, 2010, Augustine Volcano; the influence of volatile components in magmas erupted A.D. 2006 to 2,100 years before present, chapter 16 of Power, J.A., Coombs, M.L., and Freymueller, J.T., eds., The 2006 eruption of Augustine Volcano, Alaska: U.S. Geological Survey Professional Paper 1769, p. 383-423 [http://pubs.usgs.gov/pp/1769/chapters/p1769_chapter16.pdf].
Wessels, R.L., Coombs, M.L., Schneider, D.J., Dehn, Jonathan, and Ramsey, M.S., 2010, High-resolution satellite and airborne thermal infrared imaging of the 2006 eruption of Augustine Volcano, chapter 22 of Power, J.A., Coombs, M.L., and Freymueller, J.T., eds., The 2006 eruption of Augustine Volcano, Alaska: U.S. Geological Survey Professional Paper 1769, p. 527-552 [http://pubs.usgs.gov/pp/1769/chapters/p1769_chapter22.pdf].
Larsen, J.F., Nye, C.J., Coombs, M.L., Tilman, Mariah, Izbekov, Pavel, and Cameron, Cheryl, 2010, Petrology and geochemistry of the 2006 eruption of Augustine Volcano, chapter 15 of Power, J.A., Coombs, M.L., and Freymueller, J.T., eds., The 2006 eruption of Augustine Volcano, Alaska: U.S. Geological Survey Professional Paper 1769, p. 335-382 and spreadsheets [http://pubs.usgs.gov/pp/1769/chapters/p1769_chapter15].
Vallance, J.W., Bull, K.F., and Coombs, M.L., 2010, Pyroclastic flows, lahars, and mixed avalanches generated during the 2006 eruption of Augustine Volcano, chapter 10 of Power, J.A., Coombs, M.L., and Freymueller, J.T., eds., The 2006 eruption of Augustine Volcano, Alaska: U.S. Geological Survey Professional Paper 1769, p. 219-267 [http://pubs.usgs.gov/pp/1769/chapters/p1769_chapter10.pdf].
Power, J.A., Coombs, M.L., and Freymueller, J.T., eds., 2010, The 2006 eruption of Augustine Volcano, Alaska: U.S. Geological Survey Professional Paper 1769, 667 p., 1 plate, scale 1:20,000, and data files. Available online at http://pubs.usgs.gov/pp/1769/ .
Coombs, M.L., Bull, K.F., Vallance, J.W., Schneider, D.J., Thoms, E.E., Wessels, R.L., and McGimsey, R.G., 2010, Timing, distribution, and volume of proximal products of the 2006 Eruption of Augustine Volcano, chapter 8 of Power, J.A., Coombs, M.L., and Freymueller, J.T., eds., The 2006 eruption of Augustine Volcano, Alaska: U.S. Geological Survey Professional Paper 1769, p. 145-185, 1 plate, scale 1:20,000, and GIS data [http://pubs.usgs.gov/pp/1769/chapters/p1769_chapter08].
Nye, C.J., Coombs, M.L., Larsen, J., Izbekov, P., Tilman, M., and Cameron, C., 2008, Augustine Volcano: Mg, Cr, and Ni-rich: LILE, REE, and HFSE-poor [abs.]: in Abstracts of the 18th Annual V.M. Goldschmidt Conference, Geochimica et Cosmochimica Acta, v. 72, n. 12S, p. A692.
Coombs, M.L., McGimsey, R.G., and Browne, B.L., 2008, Preliminary volcano-hazard assessment for Gareloi Volcano, Gareloi Island, Alaska: U.S. Geological Survey Scientific Investigations Report 2008-5159, 29 p., 1 sheet, available at https://pubs.usgs.gov/sir/2008/5159/.
Coombs, M.L., White, S.M., and Scholl, D.W., 2007, Massive edifice failure at Aleutian arc volcanoes: Earth and Planetary Science Letters, v. 256, p. 403-418, doi: 10.1016/j.epsl.2007.01.030.
Coombs, M.L., McGimsey, R.G., and Browne, B.L., 2007, Preliminary volcano-hazard assessment for the Tanaga Volcanic Cluster, Tanaga Island, Alaska: U.S. Geological Survey Scientific Investigations Report 2007-5094, 36 p., available online at: http://pubs.usgs.gov/sir/2007/5094/ .
Coombs, M.L., Neal, C.A., Wessels, R.L., and McGimsey, R.G., 2006, Geothermal disruption of summit glaciers at Mount Spurr Volcano, 2004-6: an unusual manifestation of volcanic unrest: U.S. Geological Survey Professional Paper 1732-B, 33 p., available at http://pubs.usgs.gov/pp/pp1732/pp1732b/index.html .
Power, J.A., Nye, C.J., Coombs, M.L., Wessels, R.L., Cervelli, P.F., Dehn, J., Wallace, K.L., Freymueller, J.T., and Doukas, M.P., 2006, The reawakening of Alaska's Augustine Volcano: Eos, v. 87, n. 37, p. 373, 377.
McGimsey, R., Neal, C., Waythomas, C., Wessels, R., Coombs, M., Wallace, K., 2004, Headless debris flows from Mount Spurr Volcano, Alaska [abs.]: Transactions, American Geophysical Union, v. 85, n. 47, Abstract V43B-1430.
Browne, B. L., Coombs, M. L., and Larsen, J. F., 2004, Preliminary geology of Gareloi Volcano, western Aleutian Islands (Alaska) [abs.]: Eos, AGU Fall Meeting Supplement, v. 85, n. 47, p. V43E-1454.
Coombs, M. L., Browne, B. L., and Larsen, J. F., 2004, Preliminary geology of the Tanaga Island volcanic cluster, western Aleutians (Alaska) [abs.]: Eos, AGU Fall Meeting Supplement, v. 85, n. 47, p. V43E-1457.
Coombs M., and Browne, B., 2004, The 1929 eruption of Mount Gareloi, Alaska: A compositionally zoned, explosive fissure eruption of a predominantly mafic stratocone [abs.]: in Abstracts, IAVCEI General Assembly, Pucon, Chile, 2004, Abstract 3a-24.
Coombs, M. L., Eichelberger, J. C., and Rutherford, M. J., 2003, Experimental and textural constraints on mafic enclave formation in volcanic rocks: Journal of Volcanology and Geothermal Research, v. 119, n. 1-4, p. 125-144.
Coombs, M. L., 2001, Experimental and petrologic constraints on magma movement, storage, and interactions at two volcanoes in Katmai National Park, Alaska: University of Alaska Fairbanks unpublished Ph.D. dissertation, Fairbanks, Alaska, 214 p.
Coombs, M. L., and Gardner, J. E., 2001, Shallow-storage conditions for the rhyolite of the 1912 eruption at Novarupta, Alaska: Geology, v. 29, n. 9, p. 775-778.
Coombs, M. L., Eichelberger, J. C., and Rutherford, M. J., 2000, Magma storage and mixing conditions for the 1953-1974 eruptions of Southwest Trident volcano, Katmai National Park, Alaska: Contributions to Mineralogy and Petrology, v. 140, n. 1, p. 99-118, 1 sheet, scale unknown.
Coombs, M. L., Eichelberger, J. C., and Rutherford, M. J., 2000, Magma storage and mixing conditions for the 1953-74 eruption of southwest Trident Volcano, Katmai National Park, Alaska [abs.]: in Arctic Forum 2000, Abstracts from the Arctic Forum, Washington, DC, May 16-20, 2000, Fairbanks, AK, Arctic Research Consortium of the U.S. (ARCUS), p. 20.
Coombs, M. L., Eichelberger, J. C., and Rutherford, M. J., 1999, Experimental constraints on mafic enclave formation in volcanic rocks [abs.]: Eos, v. 80, n. 46, p. 1165.
Gardner, J.E., and Coombs, M.L., 1999, Magma storage conditions for the rhyolite of the 1912 eruption of Novarupta, Katmai National Park, Alaska [abs.]: Transactions, American Geophysical Union, v. 80, n. 46, p. F1105.
Miller, T. P., Chertkoff, D. G., Eichelberger, J. C., and Coombs, M. L., 1999, Mount Dutton volcano, Alaska: Aleutian arc analog to Unzen volcano, Japan: in Nakada, S., Eichelberger, J. C., and Shimizu, H., (eds.), Unzen eruption: Magma ascent and dome growth, Journal of Volcanology and Geothermal Research, v. 89, n. 1, p. 275-301.
Burgisser, Alain, Larsen, J. F., Hazlett, R. W., Coombs, Michelle, Campbell, Matthew, and Eichelberger, John, 1999, Preliminary investigation of the eruptive cycles of Okmok Volcano, Alaska [abs.]: Eos, v. 80, n. 46, p. 1188.
Dreher, S., Coombs, M., Larsen, J., and Eichelberger, J., 1999, The stratigraphy and petrology of the 3400 BP caldera-forming eruption of Aniakchak Volcano, Alaska [abs.]: Transactions, American Geophysical Union, v. 80, n. 17, p. S353.
Coombs, M. L., Chertkoff, D. G., and Eichelberger, J. C., 1997, Mafic enclave formation and effusive eruption at two Aleutian arc volcanoes [abs.]: Eos, v. 78, n. 46, p. 828.
Jolly, A. D., McNutt, S. R., Coombs, M. L., Stihler, S. D., and Paskievitch, J. F., 1997, Seismicity in the vicinity of the Katmai Group of volcanoes, Katmai National Park, Alaska: July 1995-March 1997 [abs.]: Eos, v. 78, n. 46, p. 442.
Coombs, M. L., 1996, The mysterious and alluring cognate xenoliths of the New Trident andesite flows, Katmai National Park, Alaska [abs.]: Eos, v. 77, n. 46, p. 770.