2026 Oak Harbor Sequence

The earthquakes in this sequence occurred just to the ESE of Oak Harbor, WA. The faulting that generated the shaking occurred deep below Puget Sound, at +/- 15 mi (25 km) depth. The Ml 3.8 earthquake that happened just before midnight on July 1st local time was widely felt in the northern Puget Sound region, including Whidbey, Camano, and the San Juan Islands, Everett, and as far as Victoria, BC and Seattle. Earthquakes of this magnitude are not uncommon in the Puget Sound region.

We are calling this a sequence because in the year prior to the Ml 3.8 mainshock of July 1st, there had been no activity in the small box that defines this event group, until the Ml 2.9 event on June 7th local time. The network then detected a few smaller aftershocks, followed by 3 more small events later in June, and then, after a small foreshock about 1 minute before, the Ml 3.8 mainshock at 11:35 pm local time occurred. We've recorded several aftershocks since the mainshock. No damage is expected for the level of shaking this earthquake caused, the maximum shaking intensity reported via the USGS "Did You Feel It" page and by the stations on our ShakeMap was intensity IV, light shaking.

This area has known NW-SE trending faults, which match the orientation of the focal mechanisms. However, because these earthquakes occurred at such great depth, it is difficult to know how they are related exactly to the faults that are mapped at the surface. Do the surface mapped faults dip steeply as far down as 15 miles? Or is there a sub-horizontal fault at greater depth that can host these types of earthquakes? These scientific questions are still not fully resolved for this region.

Should we expect more earthquakes directly related to this sequence? Yes, a few, but most likely they will be small, like the ones we had so far. Although there is always the possibility of a large earthquake happening, we frequently have earthquakes in this magnitude range in Puget Sound that are not followed by a large earthquake.

This earthquake group page will automatically be updated with more events if we detect them.