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Oregon: Risks & Trends

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This page is Oregon’s equivalent of the trend-line data behind the Case for Preparedness document’s Utah sections, sized to one state rather than the full national/global picture that document covers. Same standard: every figure below is independently sourced, and figures that vary across sources are noted as such rather than resolved to a single number that looks more precise than the underlying data actually is.

The Cascadia Subduction Zone

MetricFigureSource
Chance of M7.1+ rupture, next 50 years ~37% Oregon DOGAMI / Oregon Dept. of Emergency Management
Chance of full-margin M9.0+ rupture, next 50 years 10–15% USGS
Last full rupture January 26, 1700 (M9.0, confirmed via Japanese tsunami records) USGS, DOGAMI
Typical recurrence interval 400–600 years (range: 200–1,000) DOGAMI
Projected tsunami height, worst-case coastal areas Up to 100 ft Oregon Dept. of Emergency Management
Estimated tsunami arrival time after rupture 15–20 minutes Oregon Dept. of Emergency Management

The probability figures above describe two different thresholds, not a contradiction: a 37% chance covers any rupture of magnitude 7.1 or greater anywhere on the zone (which could mean a partial rupture affecting only part of the coast), while the 10–15% figure covers specifically a full-margin magnitude-9+ event, the “Big One” scenario that produces the 100-foot tsunami projection and the multi-week infrastructure loss Oregon’s own two-week preparedness standard is built around.

The 2020 Labor Day fires

MetricFigure
Acres burned ~1.0–1.1 million (figures vary slightly by source)
Homes destroyed 4,000+
Deaths At least 9 (some sources report up to 11)
Timeframe Most destruction occurred within a single 72-hour period over Labor Day weekend

What made this event different from Oregon’s typical fire season wasn’t just scale, it was location: an unusual east wind event pushed fire out of the Cascades and into populated valley towns (Detroit, Blue River, Phoenix, Talent) that hadn’t historically planned around wind-driven fire risk the way areas east of the Cascades do. It remains the benchmark event Oregon’s fire agencies plan against for wind-driven, structure-loss fire risk statewide.

The 2021 heat dome

MetricFigure
Portland's peak temperature 116°F, a new all-time record by nearly 10°F
Confirmed hyperthermia deaths, statewide, as of July 26, 2021 83 (State of Oregon Initial After-Action Review)
Statewide death toll cited in later reporting 116
Multnomah County deaths from the event 72, nearly all within a single five-day stretch in June 2021
Demographic pattern Most victims were older adults living alone without air conditioning

Why the death count moved over time

The gap between the 83-death count in the state’s own late-July after-action review and the 116 figure cited in later reporting isn’t a data error; it reflects medical examiners finalizing individual investigations and toxicology reports over the following weeks, the same pattern the Case for Preparedness document notes for other disasters’ initial-versus-final damage and casualty figures.

What these three have in common

Each of these is the kind of event this manual’s Tier 1–2 framing exists for: a sudden onset, a multi-day to multi-week disruption to normal services, and a real, documented history of catching people without the specific preparation that would have mattered most, water and food independence for the Cascadia scenario, defensible space and an evacuation plan for wildfire, a cooling plan and a way to check on isolated older neighbors for extreme heat. None of them are hypothetical for Oregon; all three have already happened in the last five years.

Sources