You cannot read about Pacific Northwest earthquakes for long without hitting the word Cascadia. Here is what it actually is and what it means for your coverage decision.
What Cascadia is
The U.S. Geological Survey describes the Cascadia Subduction Zone as a fault extending from Northern California to southern British Columbia, from well offshore to eastern Washington and Oregon, where the Juan de Fuca plate is sliding beneath the North American plate. It is capable of a magnitude 9 megathrust earthquake. Oregon’s emergency management materials put the fault at about 700 miles long.
The historical record
The last great Cascadia earthquake struck on January 26, 1700. The U.S. Geological Survey says it caused significant coastal subsidence and sent a tsunami all the way to Japan, where it was recorded. That event is why scientists can date the fault’s behavior at all.
What the probabilities say
The U.S. Geological Survey’s 2025 fact sheet estimates roughly a 10 to 15 percent chance of an approximately magnitude 9 Cascadia earthquake in the next 50 years, an 85 percent chance of a magnitude 6.5 or greater deep earthquake in the Puget Sound region, and a smaller chance of a major crustal fault earthquake there. Washington’s Department of Natural Resources says the state has one of the highest risks of large and damaging earthquakes in the country, and that small earthquakes happen daily, most too minor to feel.
Regional risk is not the same as your risk
Here is the part that gets lost. Cascadia is a regional hazard. Whether earthquake insurance makes sense for you depends on your specific home: its age, its construction, its foundation, your equity, your mortgage, and what deductible you could absorb. A new, bolted, wood-frame home on stable soil is a different risk than an unreinforced masonry home on fill. Cascadia explains why you should look. Your home decides what to do.
Insurance is one tool, not the only one
Earthquake coverage is a financial tool. It does not prevent damage. Preparedness and retrofitting are separate tools that reduce harm and sometimes affect eligibility. We cover the building side in earthquake retrofitting and insurance, and the decision side state by state in the Oregon and Washington guides.
The honest takeaway
Cascadia is not a prediction for a specific date, and it is not a reason to panic. It is a well-documented reason for Oregon and Washington homeowners to understand the earthquake coverage gap and decide on purpose. That is the whole point of this series. When you are ready, compare your coverage with us.
Questions to ask your advisor
- Given my home’s age and construction, how should I think about Cascadia risk?
- Is earthquake currently on my policy, or excluded like most standard forms?
- What deductible would apply, and could I absorb it after a major loss?
- How do equity and my mortgage factor into whether coverage makes sense for me?
- How do retrofitting and preparedness fit alongside, not instead of, insurance?
Want guidance first? Compare your coverage. Already know what you need? Get a quote.
Continue the series
You are reading part 6 of Earthquake Insurance in Oregon and Washington: What Homeowners Should Know.
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