Mysterious explosion on Orcas recorded by seismologists 20 miles away

A sonic boom rattled Orcas Islanders from their sleep, including retired seismologist Tom Owens, at approximately 3:30 a.m. on March 7.

“It jolted me awake and that jolt made it hard to get back to sleep,” Owens said.

His curiosity was piqued since this was not the first explosion that had awakened him. On Dec. 5, he witnessed a burst of light.

“I was kinda half awake already, so I noticed the flash followed by hearing the explosion,” Owens said. “It was probably the third explosion since I moved here and I just thought ‘this is getting strange’ and went back to sleep.”

After the March 7 incident, Owens decided it was time to reach out to the staff at Pacific Northwest Seismic Network at the University of Washington to see if it had registered on any of their equipment. And it had.

According to Mickey Cassar, Field Engineer at the University of Washington’s Pacific Northwest Seismic Network, thanks to the ShakeAlert project, funds were made available to install more stations statewide, including several in San Juan County.

ShakeAlert is an earthquake early warning detection system where Washington residents can receive early warning alerts through WEA messages, the Android operating system, or by downloading the MyShake App onto their phones. In order to provide better ShakeAlert coverage more seismic stations were needed in the region, and until recently there had only been two stations in the county: one at UW’s Friday Harbor Laboratories and one at Mount Constitution on Orcas. Now there are several across Orcas, San Juan, and Lopez. According to Cassar, the increased coverage improves another product: ShakeMap. ShakeMaps are produced after earthquakes, and allow emergency managers to identify areas that have experienced the most severe shaking. Having a handle on this information will help emergency managers prioritize resource allocation after major earthquakes.

Owens explained ShakeAlert is a system implemented to minimize the time it takes to locate an earthquake and provide that information to critical facilities as quickly as possible. New stations in the San Juan Islands can cut the time to locate a large earthquake by a few seconds, saving lives in the I-5 urban corridor.

“Text messages travel faster than seismic waves and those seconds of early warning will trigger actions that save lives and property damage. I’d prefer that we not have a big earthquake, but if we do, I look forward to seeing ShakeAlert help prevent losses,” Owens said, adding that ShakeAlert does not predict earthquakes, only cuts down on response time. “I’d say the biggest shift in my career was the recognition that ‘earthquake prediction’ probably isn’t going to pan out and that ‘Earthquake early Warning’ is a better approach.”

Due to those extra stations, recent booms were recorded extremely well.

“I was definitely surprised at how well it was recorded. It was clear that the energy was propagating closer to the speed of sound in the air than the speed of seismic waves in the earth,” Owens said. “I was a little surprised by the location. I asked Steve if it had to be at ground level versus higher in the atmosphere and he said, yes, the location was on or very close to the ground.”

Cassar was also surprised the event was well documented.

“It was interesting to have this register on stations over 20 miles away,” he said, adding that it illustrates how big the boom was.

Suspicious explosions have also occurred on San Juan Island, none of which have been solved. When the Journal pointed out the most recent San Juan report, when a post was blown up at False Bay on March 14, 2021, Cassar looked at his data and discovered that it registered on equipment at the Labs station.

Of the March 7 incident at Cresent Beach, Cassar said, “It was extremely cool to have our system capture the event, to register it on the ground using sound velocity. The community response has been interesting too. We have been able to go back and look at seven other sites, [on Orcas] over the last two years.”

According to Steve Malone, Professor Emeritus at the Department of Earth and Space Sciences at the University of Washington, forensic seismology has assisted with several well-known cases.

“[Foresnic seismology] has contributed at some level to understand the ‘event.’ The 9/11 World Trade Center collapses, big explosions like the recent one in Lebanon and, of course, nuclear testing,” Malone said. “But, I know of no cases where it has been a major contributor to solving a crime.”

Owens added that because seismologists like to explain the signals they record, their curiosity draws these scientists into the investigations.

“I’ve had similar inquiries [while working] in South Carolina where explosions are heard at night and the sheriff wants an explanation. I recall one where it happened more than once and the sheriff had a friend with a plane fly a deputy around to see if they could find a crater,” Owens said, adding that the police were unable to find the hole. “Blowing up stumps on your property is one thing, setting off devices in the middle of the night on public property is a problem,” he continued, explaining that any misjudgment of the device could cause serious injury.

San Juan County Sheriff’s Office stated in a March 8 press release that: “Based on reports the Sheriff’s Office received from the Orcas Island community, we were able to recover evidence of the explosion that occurred on Crescent Beach. While we know the time and location of the event, we are still asking for information from any home security cameras that may have picked up a vehicle or people walking in the area. We are currently working with the ATF to determine if any of the items we recovered have any identifiable value.”

When asked if Owens believed there was a connection between the incidents of mysterious booms on Orcas, he replied “December 2021 and March 2022 are almost certainly connected. [They both occured] about the same location, same time of day.”

Cassar emphasized the importance of individuals engaging in ShakeAlert, not only due to earthquake preparedness but in cases of non-earthquake-related events, including bombs.

“The sooner we know about it, the sooner we can look at the data and locate exactly where it came from,” he said.

Being able to utilize that information quickly could be crucial to investigators.

“If there are more events like this, I want the community to know we can help map and locate the events,” Cassar said.

Anyone who has information regarding the explosions should contact the San Juan County Sheriff’s Office at 360-378-4151 or the anonymous tip line: 360-370-7629.