Major quake rattles Wrangell, Southeast Alaska

A 7.5 magnitude earthquake, with an epicenter located 110 kilometers west of Craig and approximately 6 miles under the earth’s surface, struck just minutes before midnight on Friday, shaking houses across the region.

A tsunami warning was initially lodged for almost all of Southeast, including Wrangell and Petersburg, though it was cancelled within hours of the initial quake. No substantial elevation in the tide level at Wrangell or Petersburg was reported.

Although no evacuation-to-higher-ground order was instituted for Wrangell, concerned citizens were able to go to Evergreen Elementary School, which was opened just after one o’clock in the morning for anyone who wanted to be on higher ground. Petersburg residents were asked to move to higher ground and were directed to travel to the borough’s baseball field.

Wrangell Harbormaster Greg Meissner said he heard of no ill effects from the slight tidal influx and that the fleet in the harbors around the borough were safe and secure.

“I checked the tidebook and we were at low tide during the quake. Also, our streets are at around 24 feet, so even if we had a three-foot tide come in we’d still have 21 feet to go,” he said. “Plus, I got no reports of any issues at the harbors.”

According to Wrangell Light & Power superintendent Clay Hammer, no electrical outages or issues were reported across the borough.

“There was no damage whatsoever to any of our systems,” Hammer said. “I think that is a testament to the engineering design of our system coming out of Tyee. It’s excellent and the builders of that system had something like this directly in mind when they made it.”

The earthquake felt on Saturday morning was slightly larger than one that struck off the coastline of Japan in December – a 7.3 temblor that was close to the epicenter of an earlier quake that caused a tsunami and the catastrophic failure of the Fukushima Daichi nuclear power plant.

The quake is related to the 7.8 magnitude Queen Charlotte Island earthquake in October 2012, and is related to a deformation along the same plate boundary system. The Queen Charlotte fault forms the boundary between the Pacific and North American plates along the western edge of central British Columbia and southeast Alaska. In the region of this earthquake the Pacific Plate moves approximately north at a rate of 2 inches per year.

According to the Alaska Earthquake Information Center, a 4.3 magnitude aftershock happened almost 24 hours later, at 11:37 p.m. on Saturday night.