A Japanese nuclear power station was ordered today to shut down because of the danger it could spew radiation after being ruptured by an earthquake.

A panels of judges in the city of Kanazawa ruled that earthquake-resistance precautions at the Shika nuclear power plant were inadequate and based on out-of-date science. The reactor remains in operation pending an appeal, but the decision will shake Japan’s nuclear industry, which produces almost a third of the country’s electricity.

"An earthquake larger than what the electricity company had anticipated could occur, resulting in a nuclear accident and exposing residents to radiation," said the chief judge, Kenichi Ido, ruling in favour of 135 plaintiffs from across Japan. "If radioactive substances are released, the dangers of infringing upon personal rights upon residents will exceed a tolerable level."

The case focuses on two of Japan’s greatest phobias. Positioned close to the meeting place of three of the planet’s tectonic plates, the Japanese islands suffer regularly from large earthquakes, which devastated Kobe in 1995 and Tokyo in 1923. But they also have 55 nuclear reactors, several of them, like Shika, built close to active fault lines.

All are designed to withstand earthquakes up to a certain magnitude. But, just as it is impossible to predict an earthquake, it is difficult to be sure of the maximum strength of a potential tremor and the precise effect that it will have on buildings.

The plaintiffs in the civil case pointed out that an earthquake in northern Japan last year was within the limits allowed for by nuclear plant designers. But the extent of swaying which it caused in the Onagawa nuclear plant was greater than they had calculated.

"Guidelines for inspecting building’s resistance to earthquakes were established 20 years ago," a statement by the plaintiffs said. "Japan’s nuclear reactors, including the No. 2 reactor at the Shika plant, would not withstand a real earthquake."

The Shika reactor only began running on Wednesday last week and with an output of 1358 watts it is the country’s second biggest in terms of capacity. It is situated on the west side of the lonely Noto Peninsula - despite their insistence that they are safe, the operators of nuclear power plants have yet to build one in a major population centre.

But it is also close to the Ochigata fault line. An earthquake research committee appointed by the Japanese government warned of the possibility of several earthquakes occurring simultaneously on the fault, generating an earthquake of magnitude 7.6 that would severely shake the plant.

Japan’s status as the only nation to suffer atomic attack gives it an especially queasy attitude to radiation. The absence of any domestic oil or gas reserves makes it unusually dependent on nuclear power, but public faith in the industry has been shaken by a number of accidents.

In 1999 two workers at the Tokaimura plant were killed after an explosion caused when they mixed volatile ingredients in a bucket, and 600 local people were exposed to lower levels of radiation. Eighteen months ago, four workers were killed and seven others severely burned by a leak of non-radioactive steam at the Mihama plant west of Tokyo.

Three days ago, there was a minor fire at another nuclear power station in Fukui prefecture, although no radiation escaped.

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