Network for Tracking Earthquakes Exposes Alaskan Glacier Activity

Alaska's seismic network records thousands of earthquakes produced by glaciers, capturing valuable data that scientists normally cast aside but could use to better understand their behavior, new research shows.

If the current earthquake monitoring system is tweaked, years of data could display the glaciers' movement over that time span.

"In Alaska, these glacial events have been largely treated as a curiosity, a by-product of earthquake monitoring," said State Seismologist Michael West, director of the Alaska Earthquake Center, which is responsible for detecting and reporting seismic activity across Alaska.

"As we look across Alaska's glacial landscape and comb through the seismic record, there are thousands of these glacial events. We see patterns in the recorded data that raise some interesting questions about the glaciers," he added.

When a glacier loses large parts of ice, a process called calving, the Alaska Earthquake Center's monitoring system automatically records the event as an earthquake.

Normally the calving data is discarded, but scientists are finally realizing its potential.

"We have amassed a large record of glacial events by accident," West commented. "The seismic network can act as an objective tool for monitoring glaciers, operating 24/7 and creating a data flow that can alert us to dynamic changes in the glaciers as they are happening."

Since 2007, the Alaska Earthquake Center has recorded more than 2800 glacial events along 600 kilometers of Alaska's coastal mountains. These events are equivalent to earthquakes about 1 to 3 in magnitude.

Glaciers' movement normally ebbs and flows between swiftness and slowness depending on the seasons, but researchers found that their patterns began to drastically change. For example, in mid-August 2010 the Columbia Glacier's seismic activity changed radically from being relatively quiet to producing some 400 quakes to date.

When scientists intentionally study glaciers they usually focus on a single one. This data could provide them with glacial movements across the board, and it's information that's just waiting to be tapped into, according to West.

"This is low-hanging fruit," he remarked.

West presented this research yesterday at the annual meeting of the Seismological Society of America.