A 7.1 magnitude earthquake struck southern Alaska at 1030 GMT on Sunday, US Geological Survey said.
The earthquake monitoring agency, updating its earlier location for the quake, said it was centered about 83 kilometers East of Old Iliamna, and estimated it had a depth of 127 km.
It was not immediately known if it had caused any injuries or serious damage.
Twitter however was awash with posts saying the shaking was pronounced and prolonged.
“Everyone in Anchorage is awake and on Twitter right? Biggest longest #earthquake of my entire life. Family is all hanging in our bed now,” wrote @jgrenn.
Another Twitter user, @Shelbae97, wrote: “Thank Alaska for that earthquake,” and posted a photo a broken mirror and other household objects flung to her feet.
The Hawaii-based Pacific Tsunami Warning Center said there was no risk of a tidal wave “because the earthquake is located too deep inside the earth.”