"People covered their heads with their bags as dust and small debris fell," Weiss said. "Something sprung a leak, as there was a lot of water on the platform."
"It was pretty scary," Weiss said in an e-mail to a friend. "It felt pretty strong. People were scrambling for the doorways. The aftershocks are continuing even now."
People at Tokyo's Narita International Airport were told to evacuate buildings and head for the tarmac.
"It felt like a jet had come too close to the window and everything started shaking and rocking, and there was a huge rumbling noise," said David Pierson, a 32-year-old U.S. Army helicopter pilot who was waiting for a flight to Newark. "All the signs started swaying and fixtures started popping out. When I saw the panic on people's faces, I made a move for the exit."
The epicenter of the quake was 81 miles off the coast of Sendai, and it struck at a depth of 15 miles. The combination of its shallow depth and proximity to the coast made the temblor a "perfect storm for the tsunami generation" said Susan Hough of the U.S. Geological Survey in Pasadena.
Japan has a long history of large earthquakes, and its buildings are well-girded to withstand damage. Observers said this could help minimize casualties.
Photos: Scenes from the earthquake