A Tsunami with waves 10 centimeters high hit the northeastern coastline of the country on Sunday after a 7.3 magnitude quake struck, prompting officials to warn residents to evacuate for about two hours.
The Japan Meteorological Agency issued the warning, but the cancelled it in the prefectures of Iwate, Miyagi, and Fukushima, areas which were hard hit by the Tohoku earthquake on March 11.
JMA warned of slight sea-level changes for the time being, however, calling particular attention to people fishing and swimming.
The quake initially hit at 9:57 a.m. local time and the tsunami warning was cancelled at 11:45 a.m.
The March 11 tsunami reached a height of about 9.3 meters one hour after the earthquake, causing massive damage.
About 25,000 people were killed or listed missing.
The JMA issued an earthquake about 8.6 seconds after dections of seismic waves, or about 15 to 20 seconds before major shaking in the city of Sendai close to the quake's Pacific Ocean epicenter. Sendai has a population of about 1 million people.
Nevertheless, questions about the effectiveness of the warnings remain.
Did the Tsunami warning save lives? It's a very tough question that needs careful analysis, said Noritake Nishide, Director-General of the JMA's forecast department.
He said that in the coastal area of Rikuzen Takata, which was completely inundated, 2,170 of 16,640 people were reported dead or missing, which meant about 85 percent survived. The schools in Kamaishi were evacuated immediately and so almost all students survived, he said.