Earthquake in the San Juans

It was cold, crisp night, just before midnight, and Scott Damon had settled down to watch a movie on his boat, docked at West Sound Marina on Orcas Island.

He had turned on his TV with the volume up high when he felt his 85-foot boat start to shake violently.

“I thought it was an explosion on the boat,” Damon said. “So I ran down to the engine room with a flashlight to find out, but there wasn’t anything there.”

Confused, Damon returned to the galley to check out the rest of the boat. When he found everything untouched, he thought it must have been an explosion on Orcas Island, or an earthquake.

Damon would later find out the disturbance was a 4.8 magnitude earthquake that hit at 11:39 p.m., Dec. 29. The quake was 7.2 miles off the west coast of the San Juan Islands and 34 miles underground.

“I went to sea for years for the Merchant Marine, and I’ve never experienced anything like that before, so that was a first for me,” Damon said. “It must have been a heck of an after shock.”

The earthquake was felt by a number of islanders, and 301 people on San Juan Island reported feeling light shaking to the U.S. Geological Survey. 60 people reported to USGS on Lopez Island, and 108 people on Orcas Island reported feeling shaking. There have been no reports on the islands or elsewhere of damage to buildings or people. While USGS measured the quake at 4.8, its Canadian counterpart Natural Resources Canada measured it a 4.7.

“For the islands, this is a notable event. It’s one of the biggest quakes on the islands in decades, and it’s not common,” said Brendan Cowan, director of San Juan County Department of Emergency Management. “That being said, it’s not surprising in any way shape or form to seismologists and scientists.”

In this case, no tsunami warnings went into affect. The depth of the earthquake hindered the tsunami threat, because it did not cause a vertical shift in the sea floor. Earthquakes either cause the land to move up and down or side-to-side. If land mass moves up and down, one side will be higher than the other. If this movement occurs underwater, water is displaced and creates a tsunami.

The large earthquake due to hit the Pacific Northwest, often referred to as the “Big One,” is expected to be a 9.0 or higher, and could happen any time.

The last one was Jan. 26, 1700, and the Cascadia subduction zone has regularly released pressure on a 300 year basis, meaning that the Pacific Northwest is nearly 16 years over due for it.

“From my perspective this earthquake was perfect. It got a lot of people’s attention, there was no damage and no one got hurt, and it’s a good reminder to people that they need to be prepared for that,” Cowan said of the Big One.

After talking with a number of emergency response groups, Cowan said that many islanders called 911 to find out if an earthquake was occurring and to get more information.

He said that while it’s natural to want to know what’s happening, the number of callers overwhelms the dispatchers and takes emergency responders away from dealing with actual emergencies.

“In the big quake, we’re not going to have a clear picture of what happened, which is going to be uncomfortable to people. The best thing is just to sit tight and not plug up the phone lines,” Cowan said, and recommended tuning into a radio or checking the USGS websites if internet is still operational for more information.

Damon was on Mercer Island in 1964 when the 9.2 magnitude earthquake ripped apart Anchorage Alaska, sending tremors down the west coast and causing tsunami waves in Oregon and California, causing multiple deaths. He remembers telephone poles leaning back and forth, and power lines whipping around above him.