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The Islands of the Four Mountains, a small group of volcanic islands in the central Aleutian Islands, may actually be part of a single, undiscovered giant volcano in the same category as Yellowstone, new research shows.
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 Mountain Islands are a volcanic archipelago in the Central Aleutian Arc made up of six closely spaced stratovolcanoes (Carlisle, Cleveland, Herbert, Kagamil, Tana and Uliaga).
One of them, Mount Cleveland, has been one of the most active volcanoes in North America for the past 20 years with eruptive activity characterized by small explosions that produce ash clouds that s elevate 4.5-9 km (15,000-30,000 feet) above sea level.
Carnegie Institution for Science researcher Dr. Diana Roman and her colleagues studied Mount Cleveland trying to understand the nature of the archipelago.
They gathered several pieces of evidence showing that the islands could belong to an interconnected caldera.
Unlike stratovolcanoes, which tend to mine small to modest sized reservoirs of magma, a caldera is created by mining a huge reservoir in the earth’s crust.
When the reservoir pressure exceeds the force of the crust, gigantic amounts of lava and ash are released in a catastrophic eruption episode.
The eruptions forming the caldera are the most explosive volcanic eruptions on Earth and they have often had global effects.
The ash and the gas they put into the atmosphere can affect the Earth’s climate and trigger social upheaval.
“If confirmed, he would become the first of the Aleutians to hide underwater,” said Dr Roman.
“We rummaged under the sofa cushions for data. But everything we’re looking at is 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 need 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 seabed, study the volcanic rocks in more detail, collect more seismic and gravity data, and sample many other 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 the AGU Fall Meeting 2020.
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John A. Power et al. 2020. Multidisciplinary evidence of a previously unrecognized large caldera in the Four Mountain Islands, Central Aleutian Arc, Alaska. AGU20 19:28
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