A little more than a year after a magnitude 7.5 earthquake shook Southeast Alaska, aftershocks continue to register, although with diminishing magnitude and frequency.
According to information from the Alaska Earthquake Information Center, a recent aftershock with a magnitude above 4 hit last September, and a 3.5 aftershock registered just a few weeks ago. These all occurred near Craig off Prince of Wales Island.
The Queen Charlotte Fault runs up the side of Haida Gwaii in British Columbia, and along the outer coast of Southeast Alaska from Prince of Wales to Yakutat. That fault has produced several major earthquakes in the past 100 years, and the largest was a magnitude 8.1 that hit in 1949.
Last year’s 7.5 magnitude temblor triggered tsumani alerts and evacuations throughout the region.
A total of about 350 aftershocks have occurred since that Jan. 5th, 2013, earthquake. The aftershocks have definitely slowed down, though, and U.S. Forest Service Geologist Jim Baichtal said most of the recent ones would not have been noticeable to most people.
“Mostly, (earthquakes) under 4 are not felt, unless you’re incredibly close to the epicenter,” he said.
Researchers are still searching for a couple of seismographs lost after the event, that might have washed up on a remote shore. Originally, five of the devices had been lost, but three were recovered, two just west of Prince of Wales Island. A third was found in October, quite a bit north of its origin.
“That one, Teresa Hunt from the Forest Service was out with her family and found it on a beach in Yakutat,” Baichtal said. “So it was deployed off of Craig but ended up on a beach in Yakutat, so these other two may be on Kayak Island or somewhere up on the Chugach National Forest by now, depending on how they got into the currents, or if they got stranded at high tide or whatever.”
The seismographs weigh about 100 pounds each and need to be transported carefully. If somebody finds one, they can call a number on the inside of the glass sphere on top of the device. There is a reward.
A flyer about the lost seismographs, including a photograph showing what they look like, is posted below.