For the network, which has long taken pride in its staid presentation of the news, the tone was a distinct break with past, when a premium was put on avoiding panic and retaining the type of composure in the face of adversity that is so valued in Japan.

This time, the country appeared to get lucky. The 7.3-magnitude quake that struck at 5:29 p.m. under the seabed off the northeast shore of Honshu, the country’s largest island, was the largest aftershock since immediately after last year’s quake, according to the National Earthquake Information Center in Colorado. But it was small compared to last year’s 9.0 quake, which the center said released about 1,200 times more energy and which created a tsunami that wiped away seaside villages. About 18,600 people died in the double disaster.

On Friday, the water rose only about three feet in some places. And the United Nations nuclear watchdog agency said that the Japanese authorities reported they had detected no trouble at any of the nuclear plants in the area. Last year, the wall of water generated by the quake swamped the Fukushima Daiichi plant, which later had meltdowns in three reactors that spread contamination over wide areas of land.

Although buildings swayed on Friday in Tokyo and as far away as Osaka, about 550 miles from the epicenter, there were no immediate reports of heavy damage, according to news agencies. Several people were injured in the north, news reports said, but as of Saturday morning only one person was reported missing and possibly dead.

NHK reported that the man, a fisherman from the Tohoku region, took his boat out to sea to ride out any tsunami. His boat was later found about three miles offshore without him on it; but since there appeared to have been no large waves, it was unclear what might have happened to him.

Earlier, NHK appeared to be taking no chances of playing down the potential for disaster, flashing the words “Tsunami! Evacuate!” in big red letters until the warnings were lifted about two hours after the quake.

The broadcaster was stung by an outpouring of criticism last year that it had not urged people along the shoreline forcefully enough to flee the destructive waves. (The public network was also criticized for some of its post-earthquake coverage, when it was accused of going too soft on the government.)

In a country that has always kept a studied calm during its all-too-frequent earthquakes, the reaction to Friday’s quake was reported to be swift and orderly, with some residents calmly leaving for higher ground before a tsunami alert was issued. Still, residents spoke of the emotional strain from the continued aftershocks and fears of another tsunami.

A man named Taichi Sato said on Twitter: “For us, the disaster isn’t over. Something could happen that could destroy what we’ve only started to rebuild.” According to his Web site, he runs a project bringing volunteers to do tsunami cleanup in Ishinomaki, which was hard hit last year.

Elsewhere, there were signs that complacency might be creeping back. On Thursday, a radiological cleanup worker helping to remove contaminated soil from Naraha, a town in Fukushima Prefecture that remains partially evacuated because of radiation fears, appeared not to be worried about storing bags of that dirt along the coastline.

The worker, who declined to give his name, brushed off questions over whether those bags might be torn in another tsunami. “There isn’t going to be another tsunami,” he said.