A magnitude 7.3 earthquake shook northeastern Japan on Friday, leaving nine people slightly injured and triggering a tsunami alert in the same region rocked by the devastating March 2011 temblor and nuclear disaster.

According to NHK television, five people were injured in Miyagi prefecture, including a 75-year-old woman and a 2-year-old boy who suffered bumps and bruises when they fell down during the quake.

Other people suffered bruises caused by falling objects in the Kanto region, which includes Greater Tokyo, according to information gathered by emergency service personnel.

The quake struck at 5:18 p.m. and was centered in the Pacific Ocean some 240 kilometers (150 miles) off the coast of Miyagi prefecture.

It was felt in a score of Japanese prefectures, including Tokyo, where flights at the Narita International Airport were temporarily grounded and local train service was briefly interrupted.

A magnitude 6.2 aftershock occurred 13 minutes later.

The tsunami alert was in effect for two hours and one-meter (three-foot) waves were detected in the port town of Ayukawa.

The waves caused no casualties or serious damage, but prompted thousands of people to flee to high ground and brought back memories of March 11, 2011, when a magnitude 9.0 earthquake triggered a powerful tsunami that claimed 18,000 lives.

The 2011 tsunami also caused a serious disaster at the Fukushima Daiichi Nuclear Power Plant, where operators working there to keep the situation under control fled to high ground Friday after learning of the tsunami alert.

Tohuku Electric Power, which operates Fukushima Daiichi, did not report any anomalies at that facility or at the neighboring Fukushima Daini Nuclear Power Plant and said it did not detect unusually high levels of radioactivity in the area after Friday's quake. EFE