A small group of volcanic islands in Alaska’s Aleut chain may be part of an undiscovered giant volcano, say scientists who presented the results Monday, December 7, 2020, at the AGU Fall 2020 Meeting. If the researchers’ suspicions are correct, the new volcano would have belonged to the same category of volcanoes as the Yellowstone Caldera and other volcanoes that have had powerful eruptions with heavy global repercussions.
The four mountain islands in the central Aleutians are a narrow group of six stratovolcanoes called Carlisle, Cleveland, Herbert, Cagamil, Tana լի Uliaga. Stratovolcanoes are what most people think of as a volcano. A steep conical mountain with a flag of clouds և ash waving on top. They can have powerful eruptions, such as St. Mount Helens in 1980, but they are weakened by much rarer caldera-like eruptions.
Researchers from various institutions have explored Mount Cleveland, the group’s most active volcano, in an attempt to understand the nature of the Four Mountain Islands. They have gathered a great deal of evidence that the islands may belong to a single interconnected caldera.
Unlike stratovolcanoes, which tend to clog small or large magma reservoirs, a caldera is formed by hitting a huge reservoir in the earth’s crust. When the pressure of the reservoir exceeds the strength of the subsoil, huge amounts of lava ash fall in the catastrophic episode of the eruption.
Caldera eruptions are volcanic eruptions that erupt on Earth, often with global repercussions. Atmospheric ash and gas can affect the Earth’s climate and cause social upheaval. For example, the eruption of the nearby Okmok volcano in BC. In 43 AD he was recently involved in the dissolution of the Roman Republic. The proposed caldera underlying the Four Mountain Islands will be even larger than Okmok. If confirmed, it would be the first Aleut to be hidden under water.
“We were scratching under the pillows for data,” Roman said, referring to the difficulty of exploring such a remote place. “But everything we look at is a caldera in this region.”
Despite all these signs, Roman, along with John von Power, lead author of the երկր Alaska Volcano Observatory ԱՄՆ lead researcher, argue that the existence of the caldera is by no means proven. To do this, the research team must return to the islands to gather more direct evidence to fully validate their hypothesis.
“Our hope is to return to the Four Mountains Islands, to look more closely at the seabed, to study volcanic rocks in more detail, to collect more seismic data, to sample much more geothermal areas,” Roman said.
Roman said the caldera hypothesis could also help explain the frequent explosive activity on Mount Cleveland. Mount Cleveland is arguably the most active volcano in North America for at least the last 20 years. It caused gray clouds 15,000 և 30,000 feet above sea level. These eruptions pose a threat to aircraft flying through North America “Asia”.
“It probably helps us understand why Cleveland is so active,” said Power, who will present the work. “It can also help us understand what kind of eruptions are expected in the future, to better prepare for their dangers.”
Reference. “Various Evidences of the Large, Unrecognized Caldera of the Four Mountain Islands, Central Aleutian Arch, Alaska” by John A Power, Diana C. Roman, Kirsten P Nicolaysen, Pavel E Izbekov, Cynthia A Werner, Helen A Janiszewski, Daniel Evan Portner , Lara S Wagner, Terry A Plank, Daniel J. Rasmussen, John J Lyons, Matthew M Haney, Helene Le Mevel1 and Max Kaufman, 7 December 2020, AGU 2020 Fall Meeting,