Tag Archives: magma

The Islands of the Four Mountains

Volcano Week:

An Aleutian Caldera?

There is a cluster of volcanic islands in the Aleutian Chain that scientists have recently been asking a rather provocative question: Could they all be a part of one giant super volcano, similar to the Yellowstone Caldera?

This tight grouping of islands is home to six stratovolcanoes: Carlisle, Cleveland, Herbert, Kagamil, Tana and Uliaga. Mount Cleveland has been one of the most active volcanoes in North America over the past 20 years.

Most stratovolcanoes tend to have modest sized reservoirs of magma. Although that doesn’t mean they can’t have explosive eruptions, but they are dwarfed by caldera forming eruptions. A caldera is formed by tapping a huge reservoir of magma in the earth’s crust. A caldera forming eruption releases a massive amount of lava and ash, and they are catastrophic, often causing world-wide effects.*

Field work continues, although there is nothing easy about doing research in the Aleutians.

Mount Cleveland

Photo and map credit: USGS, *University of Alaska – Fairbanks

Magma Rising

Mount Edgecumbe displacement; Graphic credit: AVO

A couple of weeks ago, I posted about the swarm of earthquakes underneath Mount Edgecumbe. The numbers are in, and radar satellite data reveals a ground deformation around the volcano. Data was analyzed for the past 7.5 years, and since 2018, an uplift around Mt Edgecumbe has been constant. The peak activity, around the crater, has shown an average uplift of 3.4″ per year since 2018, and a total uplift of 10.6″.

Earthquakes in and around Mt Edgecumbe, Map credit: AVO

With the data of the ground deformation, AVO has come to the conclusion that the swarm of earthquakes is due to the movement of magma below Mount Edgecumbe, and not due to tectonic activity.

Mount Edgecumbe, a 3200 foot high stratovolcano, lies 15 miles to the west of the community of Sitka. There is no volcanic monitoring system on Edgecumbe, but there is at Sitka. AVO plans to install instruments closer to the volcano in the near future.

The rising of magma under a volcano does not necessarily mean that an eruption is imminent. The deformation and earthquakes could cease at any time. If an eruption were to occur, warning signs such as increased rate of deformation, and an increase in the earthquake swarms, would give advance warning of an eruption.