The Pribilof Islands aren’t usually prone to shaking. But more than a dozen earthquakes have been recorded in between St. Paul and St. George since Friday afternoon.
Michael West, the director of the Alaska Earthquake Information Center, describes the activity as a “swarm.”
“That is, a cluster of earthquakes that are responding to some stress in the earth that appears to be releasing itself kind of incrementally,” West says.
Most of the earthquakes have been around magnitude 4.0, although five of them exceeded 5.0M.
Residents in St. Paul and St. George have been feeling the effects. But as of Sunday afternoon, there were no reports of damage in either community. And there were no tsunami warnings, either.
The National Tsunami Warning Center will only issue an alert for Unalaska and Sand Point if the earthquakes grow stronger – above a magnitude 7.0.
“This is a special region in Alaska,” says science officer Paul Huang. “It’s unlike the front part of the Aleutians. The water [around the Pribilofs] is shallower, so we have a different criteria.”
It’s been over 20 years since the Pribilof Islands saw a significant earthquake. A magnitude 6.7 quake struck north of St. George in 1991, sending a small tsunami across the Bering Sea.
But other than that, the Pribilofs have been pretty quiet. They’re not affected by subduction along the Aleutian Chain, which causes a lot of seismic activity in the region.
West says the recent outbreak appears to be coming from a different source — tension that’s built up in the Earth’s crust.
“Most of what we know about whatever fault it is that’s active is coming from the earthquakes that we’ve actually seen in the past couple of days,” West says. “They are sort of enigmatic.”