In Japan, earthquakes are in the death-and-taxes bracket of life's certainties. Although quake talk here is usually a steady if unexciting conversational staple, thousands of summer tremors emanating from off the coast of Tokyo have triggered animated speculation about the next big one.

For more than 1,000 years, areas near Tokyo have been at the epicentre of a smasher earthquake every 60-70 years. The last one to level large parts of the capital was in 1923. So if, as the Americans say, "you do the math", the next big one is around the corner.

Or is it? Despite huge government spending on earthquake detection systems, no one can tell when it will happen. "Maybe tomorrow, maybe next week, maybe in 10 years," says one middle-aged acquaintance cheerfully. He can afford to be chirpy because he recently moved from an old wooden house - which as the rubble of the 1995 Kobe earthquake revealed is not a good place to be when the earth moves - to an earthquake-resistant apartment block.

The issue is of greater concern to Pastor Tadao Hirose, who runs a small Christian revivalist church above an adult video store and karaoke parlour in Tokyo's Shinjuku Ward. Hirose, who has obviously never been to New Orleans, says the big one will come as punishment because "Tokyo is the sinners' capital of the world" and will herald the "saving" of predominantly agnostic Japan. He claims some insight because in two visions, he says, he has walked with Jesus through the postquake rubble of Shinjuku's skyscrapers. The only building to survive was the one housing his church - which is good news for the adult video purveyor.

But for the nation's bureaucracy, the issue opens a can of more temporal worms. There was some amusement last week when a government agency announced a list of ordered steps for bank tellers to take if a big quake hits. The measures will, of course, be ignored when the tectonic plates jolt, but for the record, tellers are expected to first cease all over-the-counter services except for cash withdrawals and then ensure that ATMs remain open.

Incidentally, apart from Pastor Hirose's chapel, the safest refuge may be in the Shelter Bed made by Tokyo firm Mirai Select. When the bed's sensors detect a heavy tremor, a steel dog-kennel/garden-shed structure automatically encompasses the occupant, giving protection from falling objects. A double bed costs £14,000.