An earthquake of magnitude 6.5 has struck the Southern Idaho region in the United States, the European Mediterranean Seismological Centre (EMSC) said.
The quake - 72km west of Challis and 78 miles northeast of Boise - was at a depth of 10km, EMSC said, and struck at 5.52pm local time on Tuesday.
An entry in Volcano Discovery said: "Sustained moderate shaking for several minutes, Rumbling sound heard, people ran outside yelling. Knickknacks fell off shelf.
"Items suspended from ceiling/beams still slightly swaying 10 minutes later."
Kylie Swaim wrote on Twitter: "Just felt my first earthquake! 6.5 in Idaho. Never again please."
Another Twitter user said: "It is not a great year for the Rocky Mountains.
"I am 354 miles away from the epicenter of a 6.5 [quake] in Idaho.
"Twenty-five times more energy than the earthquake I had in Utah two weeks ago.
"I felt this 6.5 as if you were on a boat on a lake type shaking."
A third said: "Prayers to all the Idaho people that had to deal with the earthquake, stay safe."
Residents of Canadian prairie city Calgary in Alberta, also took to social media after the quake was felt there a few minutes after Idaho.
Rikki Prince said: "My apartment (on 17th floor of my building) felt really wobbly for a few seconds there. Was there an earthquake? Does Calgary get earthquakes?"