A potential change to normal tremor activity in the Pacific Northwest is not typical, but experts do not believe it poses any greater risk.
Starting around Jan. 26, slow-slip events under Vancouver Island migrated back into an area that had significant tremor activity a few months ago, instead of filling an area that has been relatively quiet since early last year.
The tremors, according to the Pacific Northwest Seismic Network, started getting stronger and lasting longer over a few days.
It appears the standard 14-month slow-slip events are covering similar areas, but are becoming scattered out over time.
"I don't think that this has any significance for hazards or changes in tectonics," a blog post from the Pacific Northwest Seismic Network states.
The Seismic Network has monitored similar activity for decades and researchers there "really don't know what variations to expect over decade periods of time."
The 14-month tremor activity affecting south British Columbia and the northern areas of Washington state have occurred since at least the 1990s.