Aftershocks of 1959 earthquake rocked Yellowstone in 2017-18

A swarm of more than 3,000 small earthquakes in the Maple Creek area (in Yellowstone National Park but outside of the Yellowstone volcano caldera) between June 2017 and March 2018 are, at least in part, aftershocks of the 1959 quake.
Source: EurekaAlert, https://www.eurekalert.org