TOKYO (AFP) - Japan was hit by a strong earthquake for the second-straight day on Saturday (Aug 20), though there were no immediate reports of damage or injuries, officials said.

A shallow magnitude-6.0 earthquake struck off the coast of northern Japan on Saturday, 167km from Miyako city, the United States Geological Survey said.

There was no threat of a tsunami following quake that had a depth of 10km, the Japan Meteorological Agency said.

The jolt came one day after a 5.3-magnitude earthquake struck north-eastern Japan off the coast of Ibaraki prefecture, just south of Fukushima.

The crippled Fukushima No. 1 nuclear power plant, battered by a massive 2011 earthquake-generated tsunami and that is currently being decommissioned, has shown no irregularities in radiation levels following Friday's jolt, officials said.

Japan sits at the junction of four tectonic plates and experiences a number of relatively violent quakes every year, but rigid building codes and their strict enforcement mean even strong tremors often do little damage.

But the massive undersea quake that hit in March 2011 sent a tsunami barreling into Japan's north-east coast, leaving more than 18,000 people dead or missing, and sending three reactors into meltdown at the Fukushima nuclear plant.

In April, two strong earthquakes hit southern Japan's Kumamoto prefecture followed by more than 1,700 aftershocks, leaving 50 dead and causing widespread damage.