Frontiers in Earth Science (2022). DOI: 10.3389 / feart.2022.868569 “width =” 699 “height =” 375 “/>

Map of the Aleutian Arc, Alaska with icy volcanoes represented by yellow circles. Ice volcanoes from left to right are Gareloi, Takavanga, Mofet, Vsevidof, Recheshnoy, Makushin, Westdale, Shishaldin, Isanotsky, Dutton, Benjamin and Spur. credit: Limits in Earth Science (2022). DOI: 10.3389 / feart.2022.868569

Alaska’s Westdahl Peak volcano last erupted in 1992, and ongoing expansion suggests a new eruption soon. Earlier, experts predicted that the next explosion would occur by 2010, but the volcano, located about 1 kilometer of glacial ice, has not yet erupted again. Using Westdahl Peak as inspiration, a new volcanic modeling study examines how glaciers affect the stability and short-term eruption cycles of volcanic systems at high latitudes – some of which exist on major air routes.


The study, led by Lillian Lucas, a student at the University of Illinois at Urbana-Champaign, with graduate student Jack Albright, former graduate student Ian Zhang and geology professor Patricia Greg, uses finite-element numerical modeling to study the stability of the rock surrounding the system. with a new twist. The team reported additional pressure from glacial volcanoes in predicting eruption times.

“Volcanic forecasting involves many variables, including the depth and size of the volcano’s magma chamber, the speed at which the magma fills that chamber, and the strength of the rocks that contain the chamber, to name a few,” Lucas said. “Measuring overpressure from polar ice caps is another critical but poorly understood variable.”

Westdahl Peak, located along the Aleutian Range in western Alaska, serves as a great model for research because it is well-instructed and constantly monitored by the Alaska Volcanic Observatory, the researchers said.

“The Aleutian Islands are quite remote, but are located along a major air route and trade route connecting North America and East Asia,” Albright said. “Volcanic ash in the atmosphere is dangerous for aircraft engines and can cause major disruptions to air traffic, so more accurate forecasts – even within months – can provide critical information on air traffic safety and nearby residents.

To determine how polar ice pressure could affect eruption times, the team conducted computer simulations of magma reservoirs of various sizes and shapes, the study said. Researchers change the flow or amount of magma that enters the system below to determine when the corresponding pressure exceeds the strength of the surrounding rock, which can cause the rock to collapse, leading to an eruption.

“We then insert parameters for different ice thicknesses in each model scenario and compare how long it takes to reach this point of failure with and without ice,” Albright said.

The study says that in terms of the time it takes to erupt Westdale without glacial ice, the presence of ice will increase the stability of the igneous system and delay the eruption date by approximately seven years.

“In particular, models without the limiting pressure of the ice cap have calculated an eruption time 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. The models are not an ideal tool to use in predicting future eruptions, but we are mainly interested in increasing this time as a result of the increased ice load. “

In general, the results of the study show that the thickness of the ice from 1 to 3 kilometers can slow the eruptions of ice-covered volcanoes for years to decades.

“These increases in time may seem insignificant on a geological scale, but they are significant on a human time scale,” Greg said. “In the future, it will be important to take the ice sheet into account in future forecasting efforts.”

The team acknowledged that previous studies looked at how seasonal changes, such as annual snow cover, could affect the interval of volcanic eruptions. However, compared to the total load that the magma chamber has to overcome to erupt, small seasonal variations are unlikely to play a major role for most systems.

“Seasonal ice loss can affect eruption times for systems close to failure,” said Jan. “It will also be important to consider how climate change and melting glaciers could affect Westdale Peak and other high-latitude volcanoes in the future.

The results of the study are published in the journal Limits in Earth Science.


Researchers have discovered a new technique for predicting volcanic eruptions


More information:
Lillian S. Lucas et al., Influence of ice caps on the mechanical stability of igneous systems: Implications for forecasting on human time scales, Limits in Earth Science (2022). DOI: 10.3389 / feart.2022.868569. www.frontiersin.org/articles/1… art.2022.868569 / full

Provided by the University of Illinois at Urbana-Champaign

Quote: Ice-covered volcanoes erupt more slowly, found the study (2022, May 10), extracted on May 10, 2022 from

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https://phys.org/news/2022-05-ice-capped-volcanoes-slower-erupt.html

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