Here is the Seattle Times reporting on an earthquake underneath Mt. Rainier in summer 1973:
And, here is the Times reporting on a 5.2 magnitude quake (5.5 on the Richter scale) on the night of February 13, 1981, a little ways northwest of Mt. St. Helens. It was just barely the largest earthquake in the NW since 1965: the series of quakes that led up to the St. Helens eruption on May 18, 1980 included many that were around a 5 magnitude.
Chronicling the Nisqually Earthquake and Other Northwest Quakes 