Scientists believe that a small group of islands off the south coast of Alaska it may actually be part of a massive volcano. Located in the Aleutian chain of Alaska, the stratovolcanoes surrounding the supposed giant caldera include Carlisle, Cleveland, Herbert, Kagamil, Tana, and Uliaga. Known as the Islands of the Four Mountains, Mt. Cleveland is the busiest of the six peaks. Stratovolcanoes comprise about 60% of the volcanoes on Earth and they are steep conical mountains with a thick layer of cloud and ash on top.
If your theory is accurate, the massive volcano will fall into the same category of volcanoes as the Yellowstone Caldera and Mount St. Helens. This means that in the past, the volcano may have caused massive explosions with deadly consequences. While calderas do not erupt frequently, they can cause widespread damage, even on a global scale.
Researchers presented his findings at the fall meeting of the American Geophysical Union on December 7, 2020. John Power, a researcher with the US Geological Survey at the Alaska Volcano Observatory, was the lead author of the study.
Evidence of a massive caldera in the middle of the islands
Researchers and scientists from many organizations have studied Mount Cleveland to understand more about the islands. The team first set out for the IFM in 2014 to search for evidence of a caldera and study the archeology of the area. A second group sailed there in subsequent years to investigate the tectonics below Mt. Cleveland.
The researchers studied the local geology, using technology like seismometers to record small tremors. They also carried out chemical analyzes to analyze the composition of gases from the soil. While the teams were working on this project, they discovered several proofs that the islands can be connected to a large caldera.
First, they noticed the puzzling half-ring shape of the Alaska IFM volcanoes. They believe that a caldera can explain this, as volcanic clusters generally form around its edges. While stratovolcanoes are formed from small to moderate sized magma deposits, calderas are created from huge magma deposits. This causes the ground at the top to collapse, creating a huge cavity in the Earth’s surface between one and 30 miles wide.
When the caldera forms, magma seeps through cracks in the earth’s crust, creating the small clumps of the volcano. Caldera eruptions cause the most destruction and can even have consequences around the world. Because they emit massive amounts of ash and gas into the atmosphere, this can cause an imbalance in the climate and society in general. For example, researchers believe that the Okmok volcano explosion in 43 BC. C. may have caused the interruption of the Roman Republic.
What does this study suggest?
If the scientists’ suspicions are correct, the caldera below the Four Mountain Islands will outshine Okmok. According to study co-author Diana Roman, it would also become the first volcano in Alaska’s Aleutian Islands to be hidden under water. The researchers believe that IFM volcanoes may connect around a possible 12-mile-wide caldera. They calculate that the huge volcano is hundreds of feet below the surface of the Pacific Ocean.
The second piece of evidence they found was rocks known as welded ignimbrites. These are formed by a large eruption, which creates volcanic ash so thick that the grains coalesce into solid rock, explains Pete Stelling. He was part of the 2015 Alaska research team, but was not involved in the new analysis.
After discovering these puzzling data, the team tried to find any other evidence that could explain the phenomenon. They studied gravity anomalies from satellite data and bathymetric studies conducted in the region just after World War II. The seafloor mapping showed several curved ridges and a depression of more than 400 feet, which could indicate a caldera.
“We’ve been digging under the sofa cushions for data,” Roman said, hinting at the difficulty of studying such remote Alaskan terrain. “But everything we look at lines up with a caldera in this region.”
Scientists need to do more studies to confirm the Alaskan caldera.
However, the researchers say they will need more to reach a clear conclusion despite all the evidence. To accomplish this, the team will plan future trips to the islands and collect more direct evidence.
“Our hope is to go back to the Four Mountain Islands and take a closer look at the seafloor, study the volcanic rocks in greater detail, collect more seismic and gravitational data, and sample many more geothermal areas,” Roman said.
His hypothesis about the caldera may explain the recurrent volcanic activity that occurs on Mt. Cleveland, Roman said. The most active volcano in North America for the past two decades, it has produced ash clouds around 15,000 to 30,000 feet above sea level. These frequent explosions can create dangerous flight conditions for pilots navigating the congested routes between North America and Asia. With tens of thousands of people flying over the volcano every day, scientists have a vital mission to accomplish.
The caldera hypothesis could also help explain the frequent explosive activity observed at Mount Cleveland, Roman said. Mount Cleveland is possibly the most active volcano in North America for at least the past 20 years. It has produced ash clouds as high as 15,000 to 30,000 feet above sea level. These eruptions pose a hazard to aircraft traveling the busy air routes between North America and Asia. They stated:
“It potentially helps us understand what makes Cleveland so active. It can also help us understand what types of eruptions to expect in the future and better prepare for their dangers. “
If their hypothesis is correct, the team believes that the alleged caldera may form from a near “super eruption.” Scientists estimate that the IFM explosion was about one-tenth the size of the Yellowstone eruption around 640,000 years ago.
Final thoughts on the Alaska island chain as part of a supervolcano.
Scientists believe that a giant caldera may be hidden under part of the Aleutian Islands in Alaska. While they have not confirmed this, the evidence seems to accumulate after further investigation. The half-ring shape of the IFM volcanoes, the discovery of welded ignimbrites, and the mapping of the seafloor point to a possible caldera. However, even if their suspicions are confirmed, the team wants to emphasize that this would not necessarily indicate a future catastrophe.