M1.5 earthquake 45 km SSE of Mammoth, Wyoming

A magnitude 1.5 earthquake struck 45 km SSE of Mammoth, Wyoming on Mon, Oct 8, 2018, 5:38 AM MDT (11:38 UTC), 2 km (1 mi) below the surface.

A larger quake followed: M2.7 72 km ESE of West Yellowstone, Montana. This one was a foreshock.

Map

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

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: 29 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 uu60300092. Read Thu, Oct 1, 2026, 1:43 AM UTC.