TOKYO (REUTERS/AFP) - An earthquake with a preliminary magnitude of 5.4 struck north of Tokyo on Monday (May 16), but there was no immediate worry of a tsunami.
The quake struck at 9.23pm local time in Ibaraki prefecture, 41km north-east of Tokyo, at a depth of 37km, the United States Geological Survey said, putting the magnitude at 5.4. It was felt in large parts of eastern Japan.
The Japanese authorities said there was no danger of a tsunami.
All trains on the Tokyo Metro were halted for four minutes, according to media reports.
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 south-western Japan, killing nearly 50 people.