A magnitude-3.6 earthquake struck almost 50 kilometres from Seattle on Thursday night and was felt as far away as Sooke and Sidney.
The U.S. National Geologic Survey said the quake occurred at a depth of 54.1 km about 17 kilometres west of Lofall, Washington.
Earthquakes can occur anywhere from the surface of the Earth to about 700 kilometres below, the USGS notes.
Shaking is felt more in shallow temblors — those that occur within 70 km of the surface — than in deep ones.
Dozens of people reported to the USGS that they had felt the earthquake.
