M2.5 earthquake 13 km SSW of Grace, Idaho

A magnitude 2.5 earthquake struck 13 km SSW of Grace, Idaho on Sat, Feb 23, 1985, 10:37 PM MST (05:37 UTC), 10 km (6 mi) below the surface.

A larger quake followed: M3.6 9 km ENE of Star Valley Ranch, Wyoming. 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
2.53	Md, duration	University of Utah Seismograph Stations	Preferred · Final · 3 stations
2.7	ML, local (Richter)	USGS National Earthquake Information Center	Reviewed

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: 6 in the 60 days after this one and 11 in the 30 days before it.

From the USGS Earthquake Hazards Program and its partner networks, event uu50019360 (also filed as usp0002c6h). Read Thu, Oct 1, 2026, 2:16 PM UTC.