QuakeIndex

Fault · Washington

Olympia structure

89 kmlong (55 mi), as mapped
not measuredhow fast it slips
< 15,000 yearssince it last broke the surface
3quakes of M2.5+ within 10 km since 2016

Updated , with the latest earthquake of M2.5 or more within 10 km of the trace: M 3.2, 3 km W of Skokomish, Washington.

In plain English

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

The largest earthquake recorded near it was M 6.7 in 1949 (4 km WNW of Roy, Washington) — about 350,000 times the energy of an M3.0, the size people start to feel. It released about 170 kilotons of TNT.

This week vs. its last ten years

Too quiet to rank: fewer than half a year's worth of weeks with any M1.5+ quake within 5 km, in ten years. A single quake here would read as "unusual", so we do not score it.

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

Seattle faultSouthern Whidbey Island faultTacoma faultSaddle Mountain faults M 6.7 · 1949 · 4 km WNW of Roy, Washington
The Olympia structure as mapped at the surface (glowing), with the other mapped faults nearby, 3 of the M2.5+ earthquakes within 10 km of it since 2016 (dots) and the epicentres of the large historic earthquakes recorded near it (rings). 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 6.7 4 km WNW of Roy, Washington
    April 13, 1949 · epicentre 12 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 3.2 3 km W of Skokomish, Washington
    2021-06-22 · 5 km from the trace
  2. M 3.8 3 km WSW of Skokomish, Washington
    2021-06-12 · 4 km from the trace
  3. M 2.8 8 km SW of Skokomish, Washington
    2019-02-15 · 1 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.