Tokyo (AsiaNews) - The Japanese authorities have provided alarming data on the leakage of radiation from nuclear power plant in Fukushima, where this morning a reactor blew up. According to authorities, the amount of radiation leaking from the reactor is 1, 015 microsievert (1 sievert) per hour, equal to the annual level of emissions. The human body can withstand up to a maximum of 2 siviert. The Tokyo Electric Power Co (TEPCO) said that the leakage is necessary to help cool the reactor.

Authorities have evacuated more than 51 thousand people in a 10 km radius of the reactor with teams of fire-fighters specialised in safety of nuclear installations on their way. Officials say that the pressure inside the reactor is increasing, but for now exclude the risk of nuclear fusion.

The blast occurred at 3.36 am local time, preceded by a cloud of white smoke. According to Tepco, the explosion was caused by the hydrogen used to cool the plants, which was affected by the strong earthquake. Four workers were involved in the incident, but so far there is no clear information on their conditions. To date the only similar incident in history occurred in 1979 in the nuclear power plant at Three Mile Island, Pennsylvania (USA).

In these hours, Japan is experiencing one of the most terrible moments in its history. According to seismologists the earthquake yesterday off the coast of Sendai was the strongest earthquake in 100 years of records in the country. The tsunami caused by the earthquake one of the worst in history. So far, the toll is of 1400 is dead, but it is expected to increase.

Meanwhile the tales of survivors from the north-eastern prefectures of Japan, the hardest hit by the tidal wave, are beginning to trickle trough.

"I've never seen anything like it - says Ken Hoshi, a local government official in Ishinomaki, Miyagi Prefecture - the water reached the train station half a mile away from the coast." Hoshi said that the raging waters swept away houses like toys and he was saved only because the building where he works is several floors high. "I'm worried for my family - he added - I can not contact anyone. But it is my duty to survive so I am preparing to spend the night in my office. "

Other witnesses say that in Aomori city, five large ships were overturned and are caught keel up in the trees of the road that flanks the harbour. In the city of Ibaraki survivors tell of houses carried inland like boats and thousands of cars bobbing on the water like corks. The first rescue teams to arrive in the tsunami-hit areas say that the towns on the coast have been wiped out.

Severe damages were also recorded in the prefectures of the country further inland, where bridges and roads have collapsed in the area close to the capital. AsiaNews sources say that several factories and oil refineries on the outskirts of Tokyo are still on fire and all the gas supplies are interrupted. In the centre of the city transport is not running and thousands of people are trying to reach their homes on foot. However sources claim that the earthquake-resistant structures held up and the population is gearing up to contact relatives and friends living in areas affected by the tsunami.