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
Augustine Volcano - The influence of volatile components in magmas erupted A.D. 2006 to 2,100 years before present: Chapter 16 in The 2006 eruption of Augustine Volcano, Alaska Augustine Volcano - The influence of volatile components in magmas erupted A.D. 2006 to 2,100 years before present: Chapter 16 in The 2006 eruption of Augustine Volcano, Alaska
The petrology and geochemistry of 2006 eruptive products of Augustine Volcano, Alaska, have been investigated through analyses of whole-rock samples, phenocrysts, silicate melt inclusions, and matrix glasses to constrain processes of magma evolution, eruption, and degassing. Particular attention was directed toward the concentrations and geochemical relationships involving the magmatic...
Authors
James D. Webster, Charlie Mandeville, Beth Goldoff, Michelle L. Coombs, Christine Tappen
Petrology and geochemistry of the 2006 eruption of Augustine Volcano: Chapter 15 in The 2006 eruption of Augustine Volcano, Alaska Petrology and geochemistry of the 2006 eruption of Augustine Volcano: Chapter 15 in The 2006 eruption of Augustine Volcano, Alaska
Deposits from the 2006 eruption of Augustine Volcano, Alaska, record a complex history of magma mixing before and during the eruption. The eruption produced five major lithologies: low-silica andesite scoria (LSAS; 56.5 to 58.7 weight percent SiO2), mostly during the initial explosive phase; high-silica andesite pumice (HSA; 62.2 to 63.3 weight percent SiO2), prevalent during the...
Authors
Jessica F. Larsen, Christopher J. Nye, Michelle L. Coombs, Mariah Tilman, Pavel Izbekov, Cheryl Cameron
Preliminary slope-stability analysis of Augustine Volcano: Chapter 14 in The 2006 eruption of Augustine Volcano, Alaska Preliminary slope-stability analysis of Augustine Volcano: Chapter 14 in The 2006 eruption of Augustine Volcano, Alaska
Augustine Volcano has been a prolific producer of large debris avalanches during the Holocene. Originating as landslides from the steep upper edifice, these avalanches typically slide into the surrounding ocean. At least one debris avalanche that occurred in 1883 during an eruption initiated a far-traveled tsunami. The possible occurrence of another edifice collapse and ensuing tsunami...
Authors
Mark E. Reid, Dianne L. Brien, Christopher F. Waythomas
Ejecta and landslides from Augustine Volcano before 2006: Chapter 13 in The 2006 eruption of Augustine Volcano, Alaska Ejecta and landslides from Augustine Volcano before 2006: Chapter 13 in The 2006 eruption of Augustine Volcano, Alaska
A late Wisconsin volcano erupted onto the JurassicCretaceous sedimentary bedrock of Augustine Island in lower Cook Inlet in Alaska. Olivine basalt interacting with water erupted explosively. Rhyolitic eruptive debris then swept down the south volcano flank while late Wisconsin glaciers from mountains on western mainland surrounded the island. Early to middle Holocene deposits probably...
Authors
Richard B. Waitt
Pyroclastic flows, lahars, and mixed avalanches generated during the 2006 eruption of Augustine Volcano: Chapter 10 in The 2006 eruption of Augustine Volcano, Alaska Pyroclastic flows, lahars, and mixed avalanches generated during the 2006 eruption of Augustine Volcano: Chapter 10 in The 2006 eruption of Augustine Volcano, Alaska
Each of the three phases of the 2006 eruption at Augustine Volcano had a distinctive eruptive style and flowage deposits. From January 11 to 28, the explosive phase comprised short vulcanian eruptions that punctuated dome growth and produced volcanowide pyroclastic flows and more energetic hot currents whose mobility was influenced by efficient mixing with and vaporization of snow...
Authors
James W. Vallance, Katharine F. Bull, Michelle L. Coombs
A parametric study of the January 2006 explosive eruptions of Augustine Volcano, using seismic, infrasonic, and lightning data: Chapter 4 in The 2006 eruption of Augustine Volcano, Alaska A parametric study of the January 2006 explosive eruptions of Augustine Volcano, using seismic, infrasonic, and lightning data: Chapter 4 in The 2006 eruption of Augustine Volcano, Alaska
A series of 13 explosive eruptions occurred at Augustine Volcano, Alaska, from January 11–28, 2006. Each lasted 2.5 to 19 minutes and produced ash columns 3.8 to 13.5 km above mean sea level. We investigated various parameters to determine systematic trends, including durations, seismic amplitudes, frequency contents, signal characteristics, peak acoustic pressures, ash column heights...
Authors
Stephen R. McNutt, Guy Tytgat, Steven A. Estes, Scott D. Stihler
Using seismic b-values to interpret seismicity rates and physical processes during the preeruptive earthquake swarm at Augustine Volcano 2005-2006: Chapter 3 in The 2006 eruption of Augustine Volcano, Alaska Using seismic b-values to interpret seismicity rates and physical processes during the preeruptive earthquake swarm at Augustine Volcano 2005-2006: Chapter 3 in The 2006 eruption of Augustine Volcano, Alaska
We use seismic b-values to explore physical processes during the Augustine Volcano 2005–6 preeruptive earthquake swarm. The preeruptive earthquake swarm was divided into two parts: the “long swarm,” which extended from April 30, 2005, to January 10, 2006; and the "short swarm," which started 13 hours before the onset of explosive activity on January 11, 2006. Calculations of b-value for...
Authors
Katrina M. Jacobs, Stephen R. McNutt
A two-step procedure for calculating earthquake hypocenters at Augustine Volcano: Chapter 7 in The 2006 Eruption of Augustine Volcano, Alaska A two-step procedure for calculating earthquake hypocenters at Augustine Volcano: Chapter 7 in The 2006 Eruption of Augustine Volcano, Alaska
This chapter describes a two-step technique for determining earthquake hypocenters at Augustine Volcano. The algorithm, which was originally developed in the mid-1970s, was designed both to overcome limitations in the standard earthquake-location programs available at the time and to take advantage of the detailed seismic-velocity information obtained at Augustine Volcano. Hypocenters...
Authors
Douglas J. Lalla, John A. Power
Distal volcano-tectonic seismicity near Augustine Volcano: Chapter 6 in The 2006 eruption of Augustine Volcano, Alaska Distal volcano-tectonic seismicity near Augustine Volcano: Chapter 6 in The 2006 eruption of Augustine Volcano, Alaska
Clustered earthquakes located 25 km northeast of Augustine Volcano occurred more frequently beginning about 8 months before the volcano’s explosive eruption in 2006. This increase in distal seismicity was contemporaneous with an increase in seismicity directly below the volcano’s vent. Furthermore, the distal seismicity intensified penecontemporaneously with signals in geodetic data that...
Authors
Michael A. Fisher, Natalia A. Ruppert, Randall A. White, Ray W. Sliter, Florence L. Wong
Earthquake waveform similarity and evolution at Augustine Volcano from 1993 to 2006: Chapter 5 in The 2006 eruption of Augustine Volcano, Alaska Earthquake waveform similarity and evolution at Augustine Volcano from 1993 to 2006: Chapter 5 in The 2006 eruption of Augustine Volcano, Alaska
Temporal changes in waveform characteristics and earthquake locations associated with the 2006 Augustine eruption and preeruptive seismicity provide constraints on eruptive processes within the edifice. Volcano-tectonic earthquakes occur within the upper 1 to 2 km at Augustine between and during eruptive cycles, and we use the Alaska Volcano Observatory hypocenter and waveform catalog...
Authors
Heather R. DeShon, Clifford H. Thurber, John A. Power
Seismic precursors to volcanic explosions during the 2006 eruption of Augustine Volcano: Chapter 2 in The 2006 eruption of Augustine Volcano, Alaska Seismic precursors to volcanic explosions during the 2006 eruption of Augustine Volcano: Chapter 2 in The 2006 eruption of Augustine Volcano, Alaska
The 2006 eruption of Augustine Volcano, Alaska, generated more than 3,500 earthquakes in a month-long time frame bracketing the most explosive period of activity. We examine two quantitative tools that, in retrospective analysis, were excellent indicators of imminent eruption. The first tool, referred to as the frequency index (FI), is based on a simple ratio of high- and low-frequency...
Authors
Helena Buurman, Michael E. West
Seismic observations of Augustine Volcano, 1970-2007 Seismic observations of Augustine Volcano, 1970-2007
Seismicity at Augustine Volcano in south-central Alaska was monitored continuously between 1970 and 2007. Seismic instrumentation on the volcano has varied from one to two short-period instruments in the early 1970s to a complex network comprising 8 to 10 short-period, 6 broadband, and 1 strong-motion instrument in 2006. Since seismic monitoring began, the volcano has erupted four times...
Authors
John A. Power, Douglas J. Lalla
Science and Products
Filter Total Items: 79
Augustine Volcano - The influence of volatile components in magmas erupted A.D. 2006 to 2,100 years before present: Chapter 16 in The 2006 eruption of Augustine Volcano, Alaska Augustine Volcano - The influence of volatile components in magmas erupted A.D. 2006 to 2,100 years before present: Chapter 16 in The 2006 eruption of Augustine Volcano, Alaska
The petrology and geochemistry of 2006 eruptive products of Augustine Volcano, Alaska, have been investigated through analyses of whole-rock samples, phenocrysts, silicate melt inclusions, and matrix glasses to constrain processes of magma evolution, eruption, and degassing. Particular attention was directed toward the concentrations and geochemical relationships involving the magmatic...
Authors
James D. Webster, Charlie Mandeville, Beth Goldoff, Michelle L. Coombs, Christine Tappen
Petrology and geochemistry of the 2006 eruption of Augustine Volcano: Chapter 15 in The 2006 eruption of Augustine Volcano, Alaska Petrology and geochemistry of the 2006 eruption of Augustine Volcano: Chapter 15 in The 2006 eruption of Augustine Volcano, Alaska
Deposits from the 2006 eruption of Augustine Volcano, Alaska, record a complex history of magma mixing before and during the eruption. The eruption produced five major lithologies: low-silica andesite scoria (LSAS; 56.5 to 58.7 weight percent SiO2), mostly during the initial explosive phase; high-silica andesite pumice (HSA; 62.2 to 63.3 weight percent SiO2), prevalent during the...
Authors
Jessica F. Larsen, Christopher J. Nye, Michelle L. Coombs, Mariah Tilman, Pavel Izbekov, Cheryl Cameron
Preliminary slope-stability analysis of Augustine Volcano: Chapter 14 in The 2006 eruption of Augustine Volcano, Alaska Preliminary slope-stability analysis of Augustine Volcano: Chapter 14 in The 2006 eruption of Augustine Volcano, Alaska
Augustine Volcano has been a prolific producer of large debris avalanches during the Holocene. Originating as landslides from the steep upper edifice, these avalanches typically slide into the surrounding ocean. At least one debris avalanche that occurred in 1883 during an eruption initiated a far-traveled tsunami. The possible occurrence of another edifice collapse and ensuing tsunami...
Authors
Mark E. Reid, Dianne L. Brien, Christopher F. Waythomas
Ejecta and landslides from Augustine Volcano before 2006: Chapter 13 in The 2006 eruption of Augustine Volcano, Alaska Ejecta and landslides from Augustine Volcano before 2006: Chapter 13 in The 2006 eruption of Augustine Volcano, Alaska
A late Wisconsin volcano erupted onto the JurassicCretaceous sedimentary bedrock of Augustine Island in lower Cook Inlet in Alaska. Olivine basalt interacting with water erupted explosively. Rhyolitic eruptive debris then swept down the south volcano flank while late Wisconsin glaciers from mountains on western mainland surrounded the island. Early to middle Holocene deposits probably...
Authors
Richard B. Waitt
Pyroclastic flows, lahars, and mixed avalanches generated during the 2006 eruption of Augustine Volcano: Chapter 10 in The 2006 eruption of Augustine Volcano, Alaska Pyroclastic flows, lahars, and mixed avalanches generated during the 2006 eruption of Augustine Volcano: Chapter 10 in The 2006 eruption of Augustine Volcano, Alaska
Each of the three phases of the 2006 eruption at Augustine Volcano had a distinctive eruptive style and flowage deposits. From January 11 to 28, the explosive phase comprised short vulcanian eruptions that punctuated dome growth and produced volcanowide pyroclastic flows and more energetic hot currents whose mobility was influenced by efficient mixing with and vaporization of snow...
Authors
James W. Vallance, Katharine F. Bull, Michelle L. Coombs
A parametric study of the January 2006 explosive eruptions of Augustine Volcano, using seismic, infrasonic, and lightning data: Chapter 4 in The 2006 eruption of Augustine Volcano, Alaska A parametric study of the January 2006 explosive eruptions of Augustine Volcano, using seismic, infrasonic, and lightning data: Chapter 4 in The 2006 eruption of Augustine Volcano, Alaska
A series of 13 explosive eruptions occurred at Augustine Volcano, Alaska, from January 11–28, 2006. Each lasted 2.5 to 19 minutes and produced ash columns 3.8 to 13.5 km above mean sea level. We investigated various parameters to determine systematic trends, including durations, seismic amplitudes, frequency contents, signal characteristics, peak acoustic pressures, ash column heights...
Authors
Stephen R. McNutt, Guy Tytgat, Steven A. Estes, Scott D. Stihler
Using seismic b-values to interpret seismicity rates and physical processes during the preeruptive earthquake swarm at Augustine Volcano 2005-2006: Chapter 3 in The 2006 eruption of Augustine Volcano, Alaska Using seismic b-values to interpret seismicity rates and physical processes during the preeruptive earthquake swarm at Augustine Volcano 2005-2006: Chapter 3 in The 2006 eruption of Augustine Volcano, Alaska
We use seismic b-values to explore physical processes during the Augustine Volcano 2005–6 preeruptive earthquake swarm. The preeruptive earthquake swarm was divided into two parts: the “long swarm,” which extended from April 30, 2005, to January 10, 2006; and the "short swarm," which started 13 hours before the onset of explosive activity on January 11, 2006. Calculations of b-value for...
Authors
Katrina M. Jacobs, Stephen R. McNutt
A two-step procedure for calculating earthquake hypocenters at Augustine Volcano: Chapter 7 in The 2006 Eruption of Augustine Volcano, Alaska A two-step procedure for calculating earthquake hypocenters at Augustine Volcano: Chapter 7 in The 2006 Eruption of Augustine Volcano, Alaska
This chapter describes a two-step technique for determining earthquake hypocenters at Augustine Volcano. The algorithm, which was originally developed in the mid-1970s, was designed both to overcome limitations in the standard earthquake-location programs available at the time and to take advantage of the detailed seismic-velocity information obtained at Augustine Volcano. Hypocenters...
Authors
Douglas J. Lalla, John A. Power
Distal volcano-tectonic seismicity near Augustine Volcano: Chapter 6 in The 2006 eruption of Augustine Volcano, Alaska Distal volcano-tectonic seismicity near Augustine Volcano: Chapter 6 in The 2006 eruption of Augustine Volcano, Alaska
Clustered earthquakes located 25 km northeast of Augustine Volcano occurred more frequently beginning about 8 months before the volcano’s explosive eruption in 2006. This increase in distal seismicity was contemporaneous with an increase in seismicity directly below the volcano’s vent. Furthermore, the distal seismicity intensified penecontemporaneously with signals in geodetic data that...
Authors
Michael A. Fisher, Natalia A. Ruppert, Randall A. White, Ray W. Sliter, Florence L. Wong
Earthquake waveform similarity and evolution at Augustine Volcano from 1993 to 2006: Chapter 5 in The 2006 eruption of Augustine Volcano, Alaska Earthquake waveform similarity and evolution at Augustine Volcano from 1993 to 2006: Chapter 5 in The 2006 eruption of Augustine Volcano, Alaska
Temporal changes in waveform characteristics and earthquake locations associated with the 2006 Augustine eruption and preeruptive seismicity provide constraints on eruptive processes within the edifice. Volcano-tectonic earthquakes occur within the upper 1 to 2 km at Augustine between and during eruptive cycles, and we use the Alaska Volcano Observatory hypocenter and waveform catalog...
Authors
Heather R. DeShon, Clifford H. Thurber, John A. Power
Seismic precursors to volcanic explosions during the 2006 eruption of Augustine Volcano: Chapter 2 in The 2006 eruption of Augustine Volcano, Alaska Seismic precursors to volcanic explosions during the 2006 eruption of Augustine Volcano: Chapter 2 in The 2006 eruption of Augustine Volcano, Alaska
The 2006 eruption of Augustine Volcano, Alaska, generated more than 3,500 earthquakes in a month-long time frame bracketing the most explosive period of activity. We examine two quantitative tools that, in retrospective analysis, were excellent indicators of imminent eruption. The first tool, referred to as the frequency index (FI), is based on a simple ratio of high- and low-frequency...
Authors
Helena Buurman, Michael E. West
Seismic observations of Augustine Volcano, 1970-2007 Seismic observations of Augustine Volcano, 1970-2007
Seismicity at Augustine Volcano in south-central Alaska was monitored continuously between 1970 and 2007. Seismic instrumentation on the volcano has varied from one to two short-period instruments in the early 1970s to a complex network comprising 8 to 10 short-period, 6 broadband, and 1 strong-motion instrument in 2006. Since seismic monitoring began, the volcano has erupted four times...
Authors
John A. Power, Douglas J. Lalla