Ice-capped volcanoes slower to erupt, study finds

Date:
May 9, 2022
Source:
University of Illinois at Urbana-Champaign, News Bureau
Summary:
The Westdahl Peak volcano in Alaska last erupted in 1992, and
continued expansion hints at another eruption soon. Experts
previously forecasted the next blast to occur by 2010, but the
volcano -- located under about 1 kilometer of glacial ice --
has yet to erupt again. Using the Westdahl Peak volcano as
inspiration, a new volcanic modeling study examined how glaciers
affect the stability and short-term eruption cycles of high-
latitude volcanic systems -- some of which exist along major air
transportation routes.



FULL STORY ==========================================================================
The Westdahl Peak volcano in Alaska last erupted in 1992, and continued expansion hints at another eruption soon. Experts previously forecasted
the next blast to occur by 2010, but the volcano -- located under about
1 kilometer of glacial ice -- has yet to erupt again. Using the Westdahl
Peak volcano as inspiration, a new volcanic modeling study examined
how glaciers affect the stability and short-term eruption cycles of high-latitude volcanic systems - - some of which exist along major air transportation routes.


==========================================================================
The study, led by University of Illinois Urbana-Champaign undergraduate researcher Lilian Lucas, with graduate student Jack Albright, former
graduate student Yan Zhan and geology professor Patricia Gregg, used
finite element numerical modeling to study the stability of the rock that surrounds volcanic systems -- but with a new twist. The team accounted
for the additional pressure from glacial ice volcanoes when forecasting
the timing of eruptions.

"Volcanic forecasting involves a lot of variables, including the depth
and size of a volcano's magma chamber, the rate at which magma fills
that chamber and the strength of the rocks that contain the chamber,
to name a few," Lucas said.

"Accounting for overlying pressure from polar ice caps is another
critical, yet poorly understood, variable." The Westdahl Peak volcano,
located along the Aleutian Island chain in western Alaska, serves as a
great model for study because it is well instrumented and continuously monitored by the Alaska Volcano Observatory, the researchers said.

"The Aleutian Islands are fairly remote, but they lie along a major air transportation and trade route connecting North America and East Asia," Albright said. "Volcanic ash in the atmosphere is hazardous to aircraft
engines and can cause major disruptions in air traffic, so more accurate forecasting - - even on the scale of months -- can provide critical safety information for air traffic and nearby inhabitants." To determine how overlying pressure from polar ice can affect the timing of eruptions,
the team ran computer simulations of magma reservoirs of different
sizes and shapes, the study reported. Researchers varied the flux, or
amount of magma that enters the system from below, to determine when
the corresponding pressure exceeds the strength of the surrounding rock,
which may cause rock failure leading to an eruption.



==========================================================================
"We then insert parameters for different thickness of ice into each
model scenario and compare how long it takes to reach that point of
failure with and without ice," Albright said.

The study reported that relative to the time it should take for Westdahl
Peak to erupt without glacial ice, the presence of ice will increase the stability of the magma system and delay the eruption date by approximately seven years.

"More specifically, the models without the presence of the confining
pressure of the ice cap calculated a time to eruption of about 93 years,"
Lucas said.

"Adding a 1-kilometer-thick ice cap to the model then increases the
eruption date to approximately 100 years. Models are not a perfect tool
to use in forecasting future eruptions, however, we are mainly interested
in the increase in this time as a result of the increased ice load."
In general, the study results indicated that ice thicknesses of 1 to 3 kilometers can delay ice-covered volcano eruptions for years to decades.

"These increases in time may seem insignificant on a geologic scale, but
it is significant on the human time scale," Gregg said. "Going forward, it
will be important to account for glacial ice cover in future forecasting efforts." The team acknowledged that previous studies considered how
seasonal changes such as annual snow cover might affect the eruption
interval of volcanoes.

However, when compared with the total overlying load that the magma
chamber must overcome to erupt, small seasonal variations are unlikely
to play a major role for most systems.

"Seasonal ice loss may impact eruption timing for systems close to
failure," Zhan said. "Furthermore, it will be important to consider how
climate change and glacial ice melt might impact Westdahl Peak and other high-latitude volcanoes in the future." The results of the study are
published in the journal Frontiers in Earth Science. The National Science Foundation, NASA and the University of Illinois Department of Geology
Summer Undergraduate Research Opportunity Program supported this study.


========================================================================== Story Source: Materials provided by University_of_Illinois_at_Urbana-Champaign,_News_Bureau.

Original written by Lois Yoksoulian. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Lilian C. Lucas, John A. Albright, Patricia M. Gregg, Yan Zhan. The
Impact of Ice Caps on the Mechanical Stability of Magmatic Systems:
Implications for Forecasting on Human Timescales. Frontiers in
Earth Science, 2022; 10 DOI: 10.3389/feart.2022.868569 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/05/220509162452.htm

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