Redoubt VolcanoAlaska, USA

Mollie Taylor and Ilana Zyatitsky

Department of Geology, Colby CollegeProfessor Robert Nelson – Jan Plan 2015

Geographic Setting

• 60°29’N 152°44’W• 177 km SW of Anchorage • few hundred kilometers from ½ of Alaska’s population)

Tectonic Setting

Formation History

880,000 y.a.Early explosive stage

340,000 and 184,000 y.a.Early cone-building stage

184,000 to 10,000 y.a.Late cone-building stage

10,000 years ago to recentPost-glacial (Holocene) stage

Characteristics and Dimensions

Steep-sided, heavily-glaciated stratovolcano

Lava dome in summit crater • Contains active steam vents and fumaroles

Drift Glacier

• 3108 meters (10,197 feet) above sea level• 10 km diameter at base • 30-35 km3 volume

Eruptive History• 1778… Captain James Cook observed Redoubt

“emitting a white smoke but no fire”• 1902… Oldest historic eruption• 1966-68… 11 eruptions • 1989-90… 23 “major explosive events”• 2009… 19 “major ash producing explosions”

Seismic HistoryOctober 1989 – December 2010– 10,400+ earthquakes within 12.5 km of summit

Largest earthquake recorded:– Magnitude 3.5 4/9/09

December 1989 – April 1990

• Large explosions with volcanic ash

• Lava dome growth

• Repetitious dome failure, high altitude ash plumes, and pyroclastic flows

• Lahars and flooding

Some Effects of the 1989-90 Eruptions

• Economic losses >$169 million

• Jet aircraft’s engines

• Drift river Oil Terminal • Cook Inlet oil production

• Drift Glacier

March 2009 – April 2009

• Six months - Pre-eruptive seismic unrest • July 2008 - Strong sulfur smell• March 22nd - First magmatic explosion with

ash column – 19 major ash-producing events – Pyroclastic flows – Lava domes

• April 4th - July 1st – Final dome building

Some Effects of the 2009 Eruptions

• Airports, schools, and businesses affected• Ashfall affected ~80,000km3

• Removal of 6,000,000 gallons of crude oil• Cook Inlet oil production• Drift Glacier

Rocks and Deposits• Rocks (53.1-68.5% SiO2)

– basalt to basaltic andesite lava flows– scoria deposits– andesitic ash flow deposits– accretionary lapilli – dense glacial ice clasts

Products of 2009 Eruption• Andesitic (57.5-62.5% SiO2) lava and tephra

• plagioclase• orthoclase• clinopyroxenes, • amphiboles • iron-titanium oxides

Active Monitoring2009 • Satellites• Web cameras • Seismic monitoring• Volcanic gas measurement• Volcanogenic lightning detection • Infrasound • Radars

Today• 9 station seismic network• GPS receivers • 5-10 seismometers

Other Pertinent Info?

Tourism– Some recreational

activity

Geothermal energy– None

Hydrothermal activity– None

Future Hazards?• Volcanic ash clouds• Volcanic ash fallout

• Lahars and floods • Pyroclastic flows and surges• Debris avalanches

Predicting Future Eruptions

1989 and 2009 precursors – Increased gas emission– heat flux– snow melt in summit crater

Alaska Volcano Observatory, 2015: Redoubt: Current Activity, at http://www.avo.alaska.edu/activity/Redoubt.php (accessed 24 January, 2015)

Alaska Volcano Observatory, 2014: Redoubt Volcano description and information, at http://www.avo.alaska.edu/volcanoes/volcinfo.php?volcname=Redoubt (accessed 24 January, 2015)

Ball, Jessica, 2009: Redoubt Volcano – Alaska, at http://geology.com/volcanoes/redoubt/ (accessed 24 January 2015

Bryson, George, 2009: Fifth explosion rocks Mount Redoubt volcano, http://www.adn.com/article/20090322/fifth-explosion-rocks-mount-redoubt-volcano (accessed 24 January, 2015)

Chouet, Bernard, 2002: Volcanoes Talking, at http://www.pbs.org/wgbh/nova/volcano/chouet.html (accessed 26 January, 2015)

Fisher, Richard, 1997: Volcanoes: Crucibles of Change. Princeton, New Jersey: Princeton University Press; 153-155 pp.

Bibliography

Bibliography (cont.)Hemming, Bryan, 2009: The Road, at http://theroadcartoons.blogspot.com/2009/03/mount-redoubt-

erupts.htm (accessed 25 January, 2015)

National Park Service, 2015: Introducing Lake Clark’s Volcanoes, at http://www.nps.gov/lacl/naturescience/volcanoes.htm (accessed 24 January, 2015)

Oregon State University, 1984: Redoubt, at http://volcano.oregonstate.edu/redoubt (accessed 24 January, 2015)

Power, John, 2011. The 2009 Eruption of Redoubt Volcano, Alaska. Fairbanks, Alaska: Alaska Division of Geological & Geophysical Surveys; Report of Investigations #5.

Power, John, S.D. Stihler, B.A. Chouet, M.M. Haney and D.M. Ketner, 2011: Seismic observations of Redoubt Volcano, Alaska – 1989-2010 and a conceptual model of the Redoubt magmatic system. Journal of Volcanology and Geothermal Research, vol. 259, pp. 31-44.

The Alaska Range Project, 2013: Where the peaks have no name, at thealaskarange.com (accessed 27 January 2015)

Waythomas, Christopher F., Joseph M. Dorava, Thomas P. Miller, Christina A. Neal, and Robert G. McGimsey, 1998: Preliminary Volcano-Hazard Assessment for Redoubt Volcano, Alaska 97-857; 1-38 p.