Japan floats like a dismembered seahorse along the eastern rim of the Asian continent. Around 10,000 years ago, during the last big melt, sea levels rose enough to flood the land bridge connecting Japan with the mainland. Today Japan consists of a chain of islands (four major ones and some 3900 small ones) riding a 3000km (1860mi) arc of mountains, the tallest of which is the perfectly symmetrical Mt Fuji (3776m/12,385ft). Many of these mountains are volcanic, blessing the islands with numerous hot springs and spectacular scenery, but at the same time bringing the danger of earthquakes and tsunami (tidal waves). Japan has the dubious distinction of being one of the most seismically active regions of the world. …