Japan has lifted a tsunami warning after a 6.1-magnitude earthquake struck off its northeast coast on Monday.
The Japan Meteorological Agency earlier issued a 50-centimetre tsunami warning for the Pacific coast of Miyagi prefecture, which was devastated by a huge earthquake and tsunami on 11 March.
The United States Geological Survey had earlier observed a 6.5-magnitude quake but later downgraded its strength. The epicentre was at a depth of 17km.
There have been no reports of damage or injuries from the latest quake, which struck at 7.23am.
The weather agency said it was likely the quake was an aftershock of the one measuring 9.0 on 11 March and warned of more to come.
The death toll has now passed 10,000 and more than 17,000 people are unaccounted for.
High radiation reading wrong
The operator of a stricken nuclear power plant has admitted an extremely high radiation reading was wrong.
On Sunday, Tokyo Electric Power Company said radiation in the water at the Fukushima Daiichi No 2 reactor was 10 million times above normal, sending workers fleeing.
The company's vice-president, Sakae Muto, says the company made a mistake and is sorry for the alarm it caused. However, he says radiation levels in the water of 100,000 times higher than normal are still worrying.
Technicians have been struggling to get the crippled Fukushima plant working since it was damaged.
The Japanese government says highly radioactive water appears to be seeping from nuclear reactors, as efforts continue to find the exact source of the leak.
The head of the United Nations nuclear watchdog, Yukiya Amano, says the situation at the plant remains very serious.