Monster volcano in Alaska

“Cluster of Alaskan Islands Could be Single, Interconnected Giant Volcano,” reads the headline. A super-volcano, in other words.

We’re talking about a super-volcano even bigger than Okmok, also located in the Aleutians.

Scientists believe that Okmok’s eruption in the year 43 BCE triggered crop failures and famine around the Mediterranean Sea, which contributed to the fall of the Roman Republic.

We’re talking about a super-volcano that could trigger a volcanic winter.

Aerial oblique photo of the volcanoes in the Islands of Four Mountains, AK, taken in July 2014. In the center is the summit of Mount Tana. Behind Tana are (left to right) Herbert, Cleveland, and Carlisle Volcanoes. Credit: John Lyons / USGS.

According to a press release from the American Geophysical Union (AGU), a small group of volcanic islands in Alaska’s Aleutian chain might be part of a single, undiscovered giant volcano, say scientists presenting the findings Monday, 7 December at AGU’s Fall Meeting 2020.

If the researchers’ suspicions are correct, the newfound volcanic caldera would belong to the same category of volcanoes as the Yellowstone Caldera and other volcanoes that have had super-eruptions with severe global consequences.

Location map of the Islands of Four Mountains in the Aleutian arc. This also shows the position and approximate areas of known calderas along the arc. Credit: John Power/USGS.

The Islands of the Four Mountains in the central Aleutians is a tight group of six stratovolcanoes named Carlisle, Cleveland, Herbert, Kagamil, Tana and Uliaga. Stratovolcanoes are what most people envision when they think of a volcano: a steep conical mountain with a banner of clouds and ash waving at the summit. They can have powerful eruptions, like that of Mount St. Helens in 1980, but these are dwarfed by far less frequent caldera-forming eruptions.

Researchers from a variety of institutions and disciplines have gathered multiple pieces of evidence showing that the islands could belong to one interconnected caldera.

Even larger than Okmok

Caldera-forming eruptions are the most explosive volcanic eruptions on Earth and they often have had global effects. The ash and gas they put into the atmosphere can affect Earth’s climate and trigger social upheaval. For example, the eruption of nearby Okmok volcano in the year BCE 43 has been recently implicated in the disruption of the Roman Republic. The proposed caldera underlying the Islands of the Four Mountains would be even larger than Okmok. If confirmed, it would become the first in the Aleutians that is hidden underwater, said Diana Roman of the Carnegie Institution for Science in Washington, D.C., co-author of the study.

Despite all these signs, Roman along with John Power, a researcher with the U.S. Geological Survey at the Alaska Volcano Observatory and the study’s lead author, maintain that the existence of the caldera is not by any means proven. To do that the study team will need to return to the islands and gather more direct evidence to fully test their hypothesis.

Mount Cleveland’s summit crater emits a vigorous steam and gas plume. The small lave dome with a diameter of roughly 50 m is present within the summit crater. Credit: Cindy Werner/USGS.












The caldera hypothesis might also help explain the frequent explosive activity seen at Mount Cleveland, Roman said. Mount Cleveland is arguably the most active volcano in North America for at least the last 20 years. It has produced ash clouds as high as 15,000 and 30,000 feet above sea level. These eruptions pose hazards to aircraft traveling the busy air routes between North America and Asia.

These six stratovolcanoes are collectively known as the Islands of the Four Mountains. But they might also be connected as part of a caldera, a massive, bowl-shaped volcanic depression that can contain multiple vents, according to findings that will be presented virtually on Monday (Dec. 7) at the annual meeting of the American Geophysical Union (AGU).

Cluster of Alaskan islands could be single, interconnected giant volcano

See also:
Extreme climate after massive eruption of Alaska’s Okmok volcano in 43 BCE and effects on the late Roman Republic and Ptolemaic Kingdom

Thanks to Mickey for these links







The post Monster volcano in Alaska appeared first on Ice Age Now.

via Ice Age Now

December 8, 2020 at 10:57AM

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