M3.1 earthquake 9 km NW of Mattawa, Washington

A magnitude 3.1 earthquake struck 9 km NW of Mattawa, Washington on Sat, Dec 15, 1990, 5:20 AM PST (13:20 UTC), 3 km (2 mi) below the surface.

A larger quake followed: M3.4 9 km NW of Mattawa, Washington. This one was a foreshock.

Map

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

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
3.1	Md, duration	Pacific Northwest Seismic Network	Preferred · Final · ±0.07 · 15 stations
3.1	Md, duration	USGS National Earthquake Information Center	Reviewed

The USGS’s account of the effects of this earthquake.

CL 3.1 (SEA).

From the USGS event page for uw10269393. U.S. Geological Survey text and figures are in the public domain.

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

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

Within 100 km, magnitude 1.5 and up: 13 in the 60 days after this one and 6 in the 30 days before it.

From the USGS Earthquake Hazards Program and its partner networks, event uw10269393 (also filed as usp0004j64). Read Fri, Oct 2, 2026, 10:11 PM UTC.