Washington earthquakes

M3.8 earthquake 20 km E of Castle Rock, Washington

A magnitude 3.8 earthquake struck 20 km E of Castle Rock, Washington on Sat, Sep 5, 2026, 4:09 AM PDT (11:09 UTC), 18 km (11 mi) below the surface.

Castle Rock forecast More in Washington

Map

Where this earthquake was located, with the others nearby. Select one for its page.

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The earthquake

Magnitude: 3.8 (ML, local (Richter)), minor
Magnitude from: Pacific Northwest Seismic Network
Local time: Sat, Sep 5, 2026, 4:09 AM PDT
UTC: 2026-09-05 11:09:28 UTC
Depth: 17.7 km (11.0 mi), shallow
Epicenter: 46.246° N, 122.642° W
Region: Washington
Felt reports: 1,025
Strongest shaking: IV, light shaking
Tsunami flag: No
Status: Reviewed by a seismologist

Magnitude estimates

Different scales measure different things and differ by a few tenths. The USGS marks one as preferred, and it is the one this page uses.

Mag.	Scale	Computed by	Notes
3.75	ML, local (Richter)	Pacific Northwest Seismic Network	Preferred · Final · ±0.159073974422102 · 145 stations
3.5	Mwr, regional moment	USGS National Earthquake Information Center	Confirmed · ±0.062 · 25 stations
3.9	Mw, moment	EW	Preliminary · ±0.2 · 21 stations

Shaking

The USGS ShakeMap: shaking estimated from seismic stations and the quake’s size, on the Modified Mercalli intensity scale.

Strongest estimated: IV, light shaking
Peak ground acceleration: 1.1% of gravity
Peak ground velocity: 0.3 cm/s
Map: Automatic

USGS ShakeMap: estimated shaking intensity around the epicenter — Estimated shaking intensity. Map: USGS ShakeMap.

Did you feel it?

1,025 people reported to the USGS what they felt; the strongest reported shaking was IV, light shaking. If you felt it, tell the USGS: every report sharpens the shaking map.

Fault motion and ground failure

How the rock slipped, from the moment tensor, and the USGS estimate of landslides and liquefaction.

Faulting: Strike-slip
Moment magnitude: 3.5 Mwr
Nodal plane 1: Strike 137°, dip 72°, rake -172°
Nodal plane 2: Strike 44°, dip 82°, rake -18°

How well it is located

Reviewed by a seismologist.

Location uncertainty: About 0.1 km horizontally, 0.2 km in depth
Magnitude uncertainty: ±0.16
Depth from: From location
Station coverage gap: 17°
Stations used: 142

Nearest places

Distance and direction from each place to the epicenter, with its forecast.

Nearby

Within 100 km, magnitude 1.5 and up: 12 since this one and 9 in the 30 days before it.

After

Before

Earthquakes today Washington earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event uw714095342 (also filed as ew1788606570, us7000teiz). Read Sat, Oct 3, 2026, 7:51 PM UTC.