An earthquake shook buildings in the Japanese capital Tokyo and other areas on Monday but no damage or injuries were immediately reported.
The quake struck at 9:23 pm (1223 GMT) in Ibaraki 41 kilometres (25 miles) northeast of Tokyo at a depth of 37 kilometres, the US Geological Survey said, putting the magnitude at 5.4. It was felt in large parts of eastern Japan.
Japanese authorities said there was no danger of a tsunami.
The country sits at the meeting place of four tectonic plates -- part of the so-called Pacific "Ring of Fire" -- and experiences a number of relatively violent quakes every year.
But rigid building codes and strict enforcement mean even powerful quakes frequently do little damage.
However strong earthquakes last month hit southwestern Japan, killing nearly 50 people.