Reawakened Mount Edgecumbe Volcano Gets Seismic Network, Cataloging Activities

(Photo : Getty Images/Mario Tama)

Mount Edgecumbe volcano in Southeast Alaska has joined the Alaska Volcano Observatory's (AVO) ground-based monitoring network.

In early September, an observatory crew installed three seismic and Global Navigation Satellite System stations atop the reawakened volcano, as well as refurbished the only existing station in the area, a temporary one on neighboring Crater Ridge.

Volcanic activities

Mount Edgecumbe, also known as L'ux Shaa in Lingt, awoke in April 2022 with a series of earthquakes.

The volcano rises 3,202 feet to dominate the view about 14-15 miles west of Sitka on the southern lobe of Kruzof Island.

Edgecumbe is part of a large and mountainous group of ancient volcanoes that encompasses over 100 square miles of the island and last erupted more than 4,000 years ago.

According to 2022 study by the Alaska Volcano Observatory, computer analysis based on satellite imagery revealed that magma rose to about 6 miles from a depth of around 12 miles, causing tremors and surface deformation.

Mount Edgecumbe's nearest seismic station was erected in August 2022 on adjacent Crater Ridge, which is part of the Edgecumbe Volcanic Field.

Three new seismic and GNSS stations have been installed along the volcano's sides, roughly around 4, 7, and 10 o'clock on an analog clock.

The lone station on neighboring Crater Ridge has been refurbished, with a strengthened steel tripod replacing a makeshift GPS antenna mast.

The Alaska Volcano Observatory will now be able to learn a lot more about Mount Edgecumbe. First, however, scientists need to determine the volcano's normal condition.

"When you go to a place and start recording data, you don't know whether it shows an anomaly or whether this is the normal state of the volcano," said Ronni Grapenthin, a geodesist with the Alaska Volcano Observatory who helped with the installation. "So we start by getting a feel for how the volcano works."

When scientists have a better grasp of Mount Edgecumbe, it will be assigned a color code. The observatory employs green, yellow, orange, and red to indicate the condition of a volcano. Green indicates normal background activity, whereas red indicates that an eruption is happening or imminent.

Impact of new and upgraded stations

24 of the 34 earthquakes reported in the Mount Edgecumbe area in the last year have occurred in the two weeks following the installation's completion on August 29.

The lone seismic station on Crater Ridge assisted AVO in detecting smaller earthquakes but did not significantly improve AVO's capacity to localize such events using the regional seismic network. Because of the lack of that information, little was known about the volcano's activities.

The observatory will now be able to produce a catalog of Mount Edgecumbe's seismicity.

Changes in seismicity can then be tracked over time and linked to data from other geophysical technologies such as radar satellite measurements of ground deformation and on-the-ground GNSS devices.

In the following weeks, data from the new and updated stations will be linked into AVO's public webpage on Mount Edgecumbe.