TOKYO — Coastal residents fled to higher ground as a powerful earthquake sent a series of moderate tsunamis toward Japan’s northeastern shore today and fueled concerns about the Fukushima nuclear power plant destroyed by a tsunami five year ago.

Lines of cars snaked away from the coast in the pre-dawn hours after authorities issued a tsunami warning and urged residents to seek higher ground immediately. The warning was lifted nearly four hours later.

The magnitude 7.4 earthquake struck in the same region that was devastated by a tsunami that followed a much larger magnitude 9.0 quake in 2011, killing some 18,000 people. The U.S. Geological Survey measured today’s quake at 6.9. It was the largest in northeastern Japan since the 2011 one and some large aftershocks that day.

At least 12 people were reported injured, and Japanese TV images showed items scattered on the floor in a store, and books that had fallen from shelves in a library. The earthquake shook buildings in Tokyo, 150 miles southwest of the epicenter.

The Japan Meteorological Agency described it as an aftershock of the massive 2011 quake. It warned that another large earthquake could hit in the next few days and urged residents to remain cautious for about a week.

“Aftershocks could continue not only for five years but as long as 100 years,” Yasuhiro Umeda, a Kyoto University seismologist, said on a talk show on Japanese broadcaster NTV.

The meteorological agency said the bigger the earthquake, the longer the aftershocks last, though it didn’t say how long.

In some areas, water could be seen rushing up rivers, which funnel tsunamis to a greater height, but it remained well within flood embankments. It was eerily reminiscent of the 2011 disaster, when much larger tsunamis rushed up rivers and overflowed.

The first tsunami waves hit about one hour after the earthquake. The highest one, 4.6 feet, reached Sendai Bay about two hours after the quake.

The operator of the Fukushima Dai-ichi plant said there were no abnormalities observed at the plant, though a swelling of the tide of up to 1 meter was detected offshore.