Seismologists Studing Recent Alaska Quakes

A third moderate earthquake has rattled the ground near the village of Minto, Alaska, and the state seismologist said the area could generate much bigger quakes.

The quake on Thursday was the third of at least magnitude 5.0 in two months. The others were Aug. 3 and Monday, the Fairbanks Daily News-Miner reported.

Activity in the area has been “very vigorous,” said state seismologist Michael West, with about 1,500 quakes recorded in two months.

“That aftershock sequence did not die out like we’d normally anticipate, so that got our attention,” he said.

Minto is about 50 miles northwest of Fairbanks. Faults in the area could generate quakes of magnitude 6 or 7, West said, though it’s unlikely.

Earthquake magnitude is measured exponentially. A magnitude 6.0 quake is 30 times more powerful than a magnitude 5.0. Minto Flats in 1995 recorded a magnitude 6.5 earthquake.

The Minto quakes featured rapid, high-frequency shaking. The 2002 magnitude 7.9 Denali Fault earthquake, the largest inland quake in North America in nearly 150 years, lasted for nearly three minutes and was characterized by slow, rolling waves. It was centered 90 miles south of Fairbanks.

The National Science Foundation since August has paid to install new seismic equipment near Minto. The technology has provided “absolutely unprecedented” understanding of the area, West said.

The recent quakes occurred on a fault line that had not been documented.

“There appears to be scientific consensus in the last few weeks that these occurred on a small fault that we were unaware of,” West said.