QuakeIndex

Fault · Washington

Southern Whidbey Island fault

64 kmlong (40 mi), as mapped
0.2–1 mm/yrhow fast it slips
< 15,000 yearssince it last broke the surface
43quakes of M2.5+ within 10 km since 2016

In plain English

The two sides move 0.2 to 1 mm a year — 2 to 10 cm every century.

Its most recent surface rupture is younger than 15,000 years.

The largest earthquake recorded near it was M 4.6 in 2019 (2 km S of Roosevelt, Washington) — about 230 times the energy of an M3.0, the size people start to feel. It released about 110 tons of TNT.

This week vs. its last ten years

61/100

typical

1 quake of M1.5+ within 5 km of the trace in the last 7 days — busier than 61% of weeks since 2016. A normal week: 0–1.

Computed from the USGS catalogue · a description of the past, not a forecast · method

Cascadia fold and fault beltOlympia structureCalawah faultSeattle faultRattlesnake Mountain faultLake Creek-Boundary Creek faultUtsalady Point faultTacoma faultCherry Creek faultSaddle Mountain faults
The Southern Whidbey Island fault as mapped at the surface (glowing), with the other mapped faults nearby, 43 of the M2.5+ earthquakes within 10 km of it since 2016 (dots), . Traces: USGS Quaternary Fault and Fold Database. Historic epicentres are estimates.

Every year since 2016

Earthquakes of M2.5+ with an epicentre within 10 km of the mapped trace. Near is not the same as on: some will have slipped on neighbouring faults.

The big ones recorded near it

  1. M 4.6 2 km S of Roosevelt, Washington
    July 12, 2019 · epicentre 2 km from the trace
  2. M 4.3 Port Townsend, WA
    October 9, 2023 · epicentre 8 km from the trace

Before 1973 from the USGS ComCat historical catalogue (within 25 km; epicentres of old earthquakes are estimates). Since 2016, M4+ within 10 km.

Most recent near it

  1. M 3.0 4 km ESE of Cathcart, Washington
    2026-02-24 · 1 km from the trace
  2. M 3.0 2 km NNW of Ames Lake, Washington
    2026-01-22 · 4 km from the trace
  3. M 2.9 7 km ENE of Marrowstone, Washington
    2025-09-16 · 0 km from the trace
  4. M 2.8 3 km NE of Fall City, Washington
    2025-07-31 · 8 km from the trace
  5. M 2.8 4 km N of Echo Lake, Washington
    2025-05-31 · 1 km from the trace
  6. M 2.5 4 km ENE of Oak Bay, Canada
    2025-03-26 · 10 km from the trace

Neighbouring faults

Fault trace, slip rate and age: USGS Quaternary Fault and Fold Database (public domain), simplified for the web. Earthquakes: USGS ComCat. QuakeIndex does not forecast earthquakes; a fault's history describes the past. For early warning use ShakeAlert.