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The Four Mountain Islands, a small group of volcanic islands in central Aleutians, may actually be part of a single giant volcano to be discovered in the same category as Yellowstone, according to new research.
An oblique aerial photo of the volcanoes of the Four Mountain Islands, Alaska, taken in July 2014. In the center is the summit of Mount Tana. Behind Tana are (left to right) the Herbert, Cleveland and Carlisle volcanoes. Image credit: John Lyons / USGS.
The Four Mountains Islands are a volcanic archipelago in the central arc of the Aleutians consisting of six closely spaced stratovolcanoes (Carlisle, Cleveland, Herbert, Kagamil, Tana and Uliaga).
One of these, Mount Cleveland, is one of the most persistently active volcanoes in North America over the past 20 years with eruptive activity characterized by small explosions that produce clouds of ash that rise 4.5 to 9 km (15,000-30,000 feet) above sea level.
Dr Diana Roman, a researcher at the Carnegie Institution for Science, and her colleagues studied Mount Cleveland trying to understand the nature of the archipelago.
They collected more evidence showing that the islands could belong to an interconnected caldera.
Unlike stratovolcanoes, which tend to touch small to modest reservoirs of magma, a caldera is created by touching a huge reservoir in the earth’s crust.
When the reservoir pressure exceeds the force of the crust, huge amounts of lava and ash are released in a catastrophic eruption episode.
The eruptions that form the caldera are the most explosive volcanic eruptions on Earth and have often had global effects.
The ash and gas they release into the atmosphere can affect the Earth’s climate and trigger social upheaval.
“If confirmed, it would become the first in the Aleutians that is hidden underwater,” said Dr. Roman.
“We looked for data under the sofa cushions. But everything we look at is aligned with a caldera in this region. “
Despite all these signs, scientists argue that the existence of the caldera is by no means proven.
To do this, they will have to return to the islands and gather more direct evidence to fully test their hypothesis.
“Our hope is to return to the Four Mountain Islands and take a closer look at the seafloor, study volcanic rocks in greater detail, collect more seismic and gravity data, and sample many more geothermal areas,” said Dr. Roman.
“The caldera hypothesis could also help explain the frequent explosive activity observed at Mount Cleveland.”
The team will present the results next week at AGU Fall 2020 Meeting.
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John A. Power et al. 2020. Multidisciplinary trials for a previously unrecognized large caldera in the islands of the four mountains, in the central arc of the Aleutians, Alaska. AGU20 19:28
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