Download Volcano-Glacier Interactions during Historical Eruptions of Aleutian

Volcano-Glacier Interactions during Recent Volcanic
Unrest at Aleutian Arc Volcanoes
[*C.F. Waythomas*] (USGS, Alaska Volcano Observatory, 4230 University Drive, Suite
201, Anchorage, AK, USA, 99508; ph: 907-786-7122; fax: 907-786-7150; email:
[email protected]); C.A. Neal (USGS, Alaska Volcano Observatory, 4200 University
Drive, Anchorage, AK, USA, 99508; ph: 907-786-7458; fax: 907-786-7425; email:
[email protected]); R.G. McGimsey (USGS, Alaska Volcano Observatory, 4200
University Drive, Anchorage, AK, USA, 99508; ph: 907-786-7432; fax: 907-786-7150;
email: [email protected]); K. Bull (Alaska DGGS, Alaska Volcano Observatory,
3354 College Rd., Fairbanks, AK, USA, 99709; ph: 907-451-5055; fax: 907-455-6879;
email: [email protected]); R. Wessels (USGS, Alaska Volcano Observatory,
4200 University Drive, Anchorage, AK, USA, 99508; ph: 907-786-7492; fax: 907-7867425; email: [email protected]); M.L. Coombs (USGS, Alaska Volcano Observatory,
4200 University Drive, Anchorage, AK, USA, 99508; ph: 907-786-7403; fax: 907-7867425; email: [email protected], K.L. Wallace (USGS, Alaska Volcano Observatory,
4230 University Drive, Suite 201, Anchorage, AK, USA, 99508; ph: 907-786-7109; fax:
907-786-7150; email: [email protected]); C. Huggel (Department of Geography,
University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland; ph: +41 44 635
51 75; fax: +41 44 635 68 41; email:[email protected]
Recent unrest at Aleutian arc volcanoes has provided a number of diverse examples of
the interaction between volcanic processes and glaciers, ice and snow. The case studies
described below, illustrate how these interactions may lead to potentially hazardous
outcomes and how knowledge of these phenomena may help mitigate hazards posed by
volcano-glacier interactions elsewhere.
The 1989-90 eruption of Redoubt volcano (60.485 N, 152. 744 W) was an explosive
dome-building eruption that physically removed the upper one third of Drift Glacier, a 14
km2 valley glacier on the northeast flank of the volcano. Pyroclastic flows and surges
ravaged the lower reaches of Drift Glacier and led to lahars and floods that inundated the
Drift River valley, including an oil storage and transfer facility near the mouth of the
Drift River about 40 km downstream of the volcano. This eruption highlights pyroclastic
flow interaction with ice and snow and the subsequent generation of destructive lahars.
The 1983-84 eruption of Veniaminof volcano (56.195 N, 159.39 W) was a Strombolian
eruption from a vent within the 8-km-diameter ice-filled caldera that characterizes the
volcano. Lava flows produced during the eruption created ice cauldrons that evolved to
open melt pits with ephemeral lakes. Although catastrophic release of water and flooding
did not occur, larger eruptions that produce more extensive lava flows could lead to
outburst floods from the caldera ice field. This eruption highlights lava-flow interaction
with glacier ice.
Augustine Volcano (59.363 N, 153.435 W) erupted explosively in January- February
2006. Pyroclastic flows generated during the explosive phase of the eruption swept across
steep, extensively snow-covered slopes on all flanks of the volcano. The snow blanket
caused the flows to inflate, spread out, and form thin, sheet-like pyroclastic-flow
deposits. Pyroclastic flows erupted later, that did not interact with snow, followed
drainages and produced deposits with more classic morphology, including blocky, lobate
margins and levees. Lahars and mixed avalanches of snow, water, and pyroclastic debris
formed beyond the pyroclastic flows that swept across snow. Flow morphologies,
lithologies, and depositional contacts indicate that the lahars and mixed avalanches
evolved from these pyroclastic flows. These deposits highlight the interaction between
snow and pyroclastic debris.
Volcanic unrest at Mt. Spurr volcano (61.298 N, 152.253 W) from 2004 to present has
resulted in the development of a 200 x 200 m diameter, lake bearing melt pit at the 3374
m high summit of the volcano, and several episodes of unusual water release. Although
no eruption of the Mt. Spurr summit vent has occurred, the melt pit lake remains open
and partially ice free. This unrest highlights low-level geothermal interaction with ice and
snow.
On September 17, 2006, a major steam emission occurred at Fourpeaked volcano (58.769
N, 153.674 W) that produced a plume reaching about 6000 m above sea level.
Observations made after the event indicated that a small debris flow and several melt pits
developed on the north flank of the volcano. The debris flow was the product of an
outburst event that may have initiated the collapse of an ice vault above the newly
reinvigorated hydrothermal vent system. The collapsing ice vault is thought to have
brought glacier ice and water into rapid contact with hot gasses and rock leading to a
phreatic eruption that produced the steam plume observed on September 17, 2006. This
unrest highlights explosive water-ice-hydrothermal interaction.
These examples are representative of the diverse range of volcano-glacier interactions in
Alaska during recent periods of unrest. The high frequency and range of interactions
offers many possibilities for further study and illustrates the importance of this region as
a natural laboratory for study of volcano-ice interactions.
ABSTRACT SUBMITTED FOR POSTER SESSION
CORRESPONDING AUTHOR: Chris Waythomas, USGS, Alaska Volcano Observatory,
4230 University Drive, Suite 201, Anchorage, AK, 99508, [email protected]