Thousands of small tremors over the past few months, starting in May have moved Washington and Vancouver Island westward and have stopped for now. Scientist believe the offshore fault called, the Cascadia Subduction Zone could trigger a megaquake by an episode of tremors.

For more info, please read the original article by Seattle Times:
https://www.seattletimes.com/seattle-news/science/tremors-shove-washington-westward-offer-clues-into-next-big-earthquake/