For the same reason Japan is famous for its hot springs, it's also known for its tsunami-causing earthquakes. It sits near where several continental and oceanic plates meet in the Pacific Ocean, and in 1498 those plates shifted.
The resultant 8.6-magnitude earthquake triggered a 56-foot-high wave, according to the US National Geophysical Data Center. The wave hit the Japanese coast at Meiō Nankai, killing 31,000 people. The Nankai region is particularly known as an earthquake region, according to the Journal of Earth and Planetary Science Letters (pdf).
Beyond deadliness, that proneness toward earthquakes is an argument against building nuclear power plants on the energy-thirsty island, as the Monitor has reported.
