A magnitude 4.2 earthquake rattled the Kitsap Peninsula on Tuesday afternoon, striking about 3.7 miles west-northwest of Wauna at 2:05 p.m. and sending weak shaking through Seattle, Tacoma and Bremerton. By Wednesday morning, more than 9,200 people had reported feeling it, and seismologists are now watching for aftershocks that could arrive within days, weeks or even years.
The quake was initially recorded at magnitude 4.3 by the Pacific Northwest Seismic Network before being revised down to 4.2 after further review, according to FOX 13 Seattle. The station reports people mostly felt weak shaking in areas near the epicenter on the Kitsap Peninsula, including Seattle, Tacoma and Bremerton. Separately, a New York Times earthquake tracker placed the epicenter about 4 miles northwest of Wauna, or roughly 15 miles southwest of Seattle.
What Are the Odds of Another Shake?
The U.S. Geological Survey has released an aftershock forecast for the Wauna-area quake, and the numbers suggest the ground hasn't necessarily settled. Per the station's report, there is an 11% chance of another earthquake at magnitude 3.0 or higher within the next 24 hours, rising to a 25% chance within the next week. Those odds climb further over time, with a 35% chance within a month and a 50% chance within a year.
For stronger tremors, the same forecast puts the chance of a magnitude 4.0-or-greater aftershock at 1% within 24 hours, 4% within a week, 6% within a month and 12% within a year. The odds of anything approaching magnitude 6.0 remain slim — the outlet's report lists a 1-in-7,000 chance within a day, climbing only to 1-in-600 across a full year. Magnitude 7.0 aftershocks are rarer still, pegged at roughly 1-in-70,000 within the first 24 hours and 1-in-20,000 within a week.
The article notes that over the last 48 hours, multiple earthquakes were recorded across the Pacific Northwest by the USGS, underscoring how seismically active the region has been lately. The New York Times tracker adds a note of caution for residents: aftershocks can occur days, weeks or even years after the first earthquake, and they are not guaranteed to be smaller than the initial jolt.
A Region That Keeps Shaking
The Wauna quake follows a trio of sizable earthquakes off Vancouver Island late Sunday and early Monday, with magnitudes near 5.0 — specifically 4.9, 5.4 and 5.2 — as reported by the same Seattle station. On the question of just how likely a bigger quake is in the immediate aftermath, accounts diverge: the New York Times tracker states there is about a 2% chance that a larger quake will strike the area in the next day, while a separate search snippet tied to the same tracker cited a 3% figure. The discrepancy hasn't been resolved.
For broader context on what a major Puget Sound earthquake can look like, the Pacific Northwest Seismic Network points to the magnitude 6.8 Nisqually earthquake that shook the region on February 28, 2001. That quake produced two attributed aftershocks — magnitude 3.4 and 2.7 — the following day, and caused approximately $305 million in insured losses and $2 billion in total damage. PNSN also notes this type of deep intraplate earthquake occurs on average every 30 years, and estimates an 84% chance of another magnitude-6.0-or-larger earthquake happening somewhere in the region within the next 50 years.
Whether Tuesday's quake near Wauna turns out to be an isolated event or the start of a longer sequence remains to be seen. For now, the USGS forecast gives residents a framework for what to expect in the days and weeks ahead, even as the exact odds of a bigger follow-up quake are still being sorted out across different reports.
