Cascadia Subduction Zone
Pacific Northwest, USA / Canada · subduction interface · 1203.7 km of mapped active fault in 45 traces
background as of 7 November 2026.
consistent with baseline
| Window | the last 30.0 days |
|---|---|
| Earthquakes counted | 0 at M4.5 or above |
| Expected in that window | 0.14 |
What this system normally does
From 1995 to 2025 the catalogue holds 52 earthquakes of M4.5 or larger attributable to this system: about 1.73 a year. That figure is what "elevated" on this page is measured against.
The fault itself
| Mapped length | 1203.7 km |
|---|---|
| Traces | 45 |
| Tectonic setting | subduction interface |
| Slip types | Subduction_Thrust |
| Depth attributed to it | down to 700.0 km |
| Extent | 40.31 to 50.31 latitude, -128.72 to -124.74 longitude |
Recorded history
NOAA's hazard records hold 7 significant earthquakes and 3 tsunamis attributed to this system since 1700.
The deadliest was the 27 January 1700 tsunami (Cascadia Subduction Zone), which killed 2 people.
The strongest earthquake on record here was magnitude 9.0, on 27 January 1700 (Cascadia Subduction Zone).
The most recent entry is the 5 December 2024 magnitude 7.0 earthquake (California: Offshore Cape Mendocino).
| Date | What | Where | Toll |
|---|---|---|---|
| 27 January 1700 | tsunami | Cascadia Subduction Zone | 2 dead, damage $5 to 25 million |
| 27 January 1700 | magnitude 9.0 earthquake | Cascadia Subduction Zone | damage $5 to 25 million |
| 31 January 1922 | magnitude 7.6 earthquake | California: Northern | damage under $1 million |
| 25 April 1992 | magnitude 7.1 earthquake | California: Humboldt County: Ferndale, Petrolia | $75 million damage |
| 22 January 1923 | magnitude 7.1 earthquake | California: Northern | damage under $1 million |
| 5 December 2024 | magnitude 7.0 earthquake | California: Offshore Cape Mendocino | damage $1 to 5 million |
| 9 February 1941 | magnitude 6.6 earthquake | California: Northern | damage under $1 million |
| 10 January 2010 | magnitude 6.5 earthquake | California: off Coast Northern | $43 million damage |
| 25 April 1992 | tsunami (waves to 1.8 m) | Cape Mendocino, N. California | $66 million damage |
| 5 December 2024 | tsunami (waves to 0.1 m) | Cape Mendocino, N. California | - |
A dash means NOAA recorded no number, not that nobody died. Older entries are fewer because fewer were written down, not because less happened.
Recorded history: NOAA NCEI hazard databases, public domain, retrieved 2026-10-22.
Published rupture probability
USGS (Fact Sheet 2025-3050) publishes a probability for this system. It is their figure, not ours:
| Probability | 10 to 15% |
|---|---|
| For an earthquake of | M9.0 or larger |
| Within | 50 years |
| As of | 2025 |
USGS gives a range rather than a single number.
Read the issuer's own publication
Who to listen to if you live here
Washington Emergency Management Division is the agency that tells people on this system what to do. https://mil.wa.gov/earthquake (in English)
Where these numbers come from
Fault geometry, length and segment counts: GEM Global Active Faults Database (GEM GAF-DB), GEM Foundation, https://github.com/GEMScienceTools/gem-global-active-faults Licence: CC-BY-SA-4.0. Figures derived from it here are offered under the same licence. Earthquake counts, magnitudes and depths: United States Geological Survey, public domain. The activity judgement is ours, computed from those two inputs, and is not a statement by either agency.