Japanese authorities urged residents in those northeast coastal areas to leave immediately for higher ground and not return until warnings had been lifted.
The earthquake struck in the same area as the devastating 9.0-magnitude earthquake in 2011
— one of the worst ever to hit Japan — which killed more than 20,000 people and triggered a meltdown at Fukushima Daiichi nuclear power plant.
Tuesday’s quake struck 37 kilometers (23 miles) east-southeast of Namie at a depth of 11.4 kilometers (7 miles). Four aftershocks of at least magnitude 4.8 were recorded within one hour of the initial quake.
Tsunami warnings were immediately issued for waves of 1 to 3 meters (3 to 10 feet), and soon after some were spotted off the coast and more are expected, according to the Japanese Meteorological Agency.
Of prime concern was the crippled Fukushima Daiichi nuclear power plant.
A cooling pump system was temporarily stopped after the quake but soon resumed operation, a spokesman for the Tokyo Electric Power Company Inc. (TEPCO) told CNN. No abnormalities or change in radiation levels were reported.
Small tsunamis reach Japan
The first tsunami wave reached the coast at Iwaki-shi in Fukushima Prefecture at 6:29 a.m. local time. The largest so far, a 1.4-meter tsunami, was observed in Sendai, Miyagi Prefecture, at 8:03 a.m. according to JMA.
Video on social media from Onahama featured sounds of sirens in response to the warning in effect.
Images of the port showed waves that the broadcaster described as “backwash” that happens before a tsunami hits shore.
NHK urged the public to evacuate, cautioning that even if waves appear low in the ocean they can rise as they reach shore. The broadcaster reminded people to dress warmly in the cold rain and urged them to help others leave.
“Please do not think that you are safe. Please evacuate to high grounds,” the network said. “Please think about the worst-case scenario and evacuate right away.”
Earthquake felt in Tokyo
The tremors could be felt as far Tokyo, where American businessman Jonathan Swanson was having breakfast in a hotel and catching up on e-mail.
“Suddenly I felt disoriented,” he told CNN’s Michael Holmes.
Doors started to swing on cabinets and sliding doors started to move. He realized what was happening.
“You could feel the building really swaying back and forth for at least a couple of minutes. It was pretty scary.”
While he was scared he was mindful of the fact that Japan takes its earthquakes seriously. Guests appeared “calm” as staffers checked in on everyone.
“They seemed like pros about this,” he said. “Everyone very calm and collected.”
Swanson is from San Francisco and has felt his share of tremors over the years.
“But this was significantly bigger than anything I felt in San Francisco … this was just more extended. The swaying was significantly more than I’d ever felt.”
Japan’s long history of earthquakes
Earthquakes are common in Japan. The most recent was a 6.2 magnitude in late October
near Kurayoshi, a city to the west of Osaka, which caused a handful of injuries.
The epicenter of this latest earthquake was not far south of the 2011 quake
, which was so severe it moved Japan’s coast 8 feet
and shifted the Earth’s axis, ranking among the costliest natural disasters on record
The devastating 2011 earthquake created huge waves towering as high as 40 meters high.