Western Washington residents felt renewed seismic urgency this week as a magnitude 4.8 earthquake struck near Squamish, British Columbia – the strongest tremor to shake the region since February 2025 began. The quake occurred at 2:26 PM PST on February 21 at shallow 10 km depth, rattling windows across Whatcom, Skagit, and Snohomish counties according to USGS reports.
This follows heightened activity along the Cascadia Subduction Zone (CSZ), where 53 earthquakes above magnitude 1.5 have been recorded in Washington over the last 30 days. While most were minor, scientists emphasize that current patterns align with historical precursors to major seismic events.
The Cascadia Countdown
The Washington Geological Survey confirms the CSZ – capable of generating magnitude 9+ megathrust quakes – remains locked and primed for release. Last month’s 6.4 magnitude quake off Vancouver Island increased stress on adjacent fault segments according to Pacific Northwest Seismic Network models.
| Key Seismic Stats | 2025 Data |
|---|---|
| Recent 7-day quakes (M1.5+) | 15 |
| ShakeAlert warnings issued | 42 |
| Emergency drill participants | 1.2 million |
“Our sensor network shows increased ‘episodic tremor’ activity deep under Olympic National Park,” said Dr. Harold Tobin of UW’s Seismology Lab. “While not predictive, this matches patterns observed before major CSZ events in geological records.”
Preparedness Push
Washington’s upgraded ShakeAlert system now delivers warnings directly to Android devices within 8 seconds of detection. However, officials urge residents to:
- Secure heavy furniture using earthquake brackets
- Maintain 7-day emergency supply kits
- Practice Drop-Cover-Hold On drills monthly
“The next major quake isn’t an ‘if’ but ‘when’,” warned Major General Bret Daugherty of WA Emergency Management. “Our last Cascadia event was in 1700 – we’re statistically overdue.”
The state’s Earthquake Early Warning system continues expanding coverage with $12 million in federal funding approved last month to install 58 new seismic sensors by December 2025.
