Two people were injured in Miyagi and another in neighboring Fukushima prefecture, but none of the injuries were life threatening.

A strong earthquake struck northern Japan early on Saturday, causing no tsunami risk but injuring three and rocking buildings in Tokyo, authorities said.

The US Geological Survey said the 6.8 magnitude earthquake struck at a depth of 47 kilometers off the coast of Miyagi Prefecture.

Two people were injured in Miyagi and another in neighboring Fukushima prefecture, but none of the injuries were life threatening, the Fire and Disaster Management Agency said.

There was no major disruption in transportation, although the Shinkansen high-speed trains were temporarily suspended for security checks and some local lines were delayed, the East Japan Railway Co. said.

Miyagi Prefecture, in the rugged northeast of the country, was severely damaged by the 2011 earthquake and tsunami that killed more than 18,000.

Japan’s Nuclear Regulatory Authority said no anomalies were reported at nuclear power plants, including the Fukushima Daiichi, which melted after the 2011 disaster.

At the end of last month, another strong earthquake struck off Miyagi Prefecture, triggering a tsunami warning over part of the northern coast. No major damage was reported, but several people were slightly injured.

In mid-February, another powerful earthquake in the region killed one person and left more than 180 injured, although most of the injuries were minor.

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