08/10/2009 at 05:00 PM EDT
is all shook up – literally.
The singer, who flew to Japan over the weekend, was shocked by the jolt of a
magnitude 6.6 earthquake that hit early Tuesday morning.
"Thought I was hallucinating," she Tweeted Monday
. "I have never felt anything like this in my life. Laying in bed watching CNN."
The earthquake struck Japan's Tsuruga Bay, which is southwest of Tokyo, at 5:07 a.m. local time on Tuesday, according to the National Weather Agency. No casualties were immediately reported.
Simpson, who recently split from boyfriend Tony Romo, is starting work on her new VH-1 TV show The Price of Beauty,
which will follow Simpson as she tours seven countries to document what lengths women go to achieve beauty.