MAMMOTH, Wyo. – A small earthquake shook the Yellowstone region early Thursday, lightly rattling areas near the Wyoming-Montana-Idaho border. The U.S. Geological Survey reported a magnitude 2.8 quake early Friday, centered roughly 22 kilometers south-southwest of Mammoth and nine kilometers deep inside Yellowstone National Park.
According to the University of Utah Seismograph Stations, which monitors the Yellowstone seismic network, no damage or injuries were reported. The shallow quake struck beneath a remote section of the park west of Norris Geyser Basin, an area known for frequent minor seismic swarms. Scientists described the event as part of routine tectonic and hydrothermal activity common in the Yellowstone Plateau.
Though the shaking was too weak to be widely felt, the event underscores the park’s constant geological motion. Park rangers confirmed no impacts to geyser operations, roads, or visitor access. U.S. Highway 191 and Highway 89 remained open overnight.
Emergency officials in Gallatin and Teton counties encouraged residents and travelers to stay aware of basic earthquake safety — secure items that could fall, keep emergency kits stocked, and know safe shelter spots if a stronger event occurs. While Thursday’s tremor was minor, Yellowstone averages thousands of such quakes each year, with most going unfelt by humans.
