Major quake to hit Tokyo within years?

Tokyo has a 70 per cent chance of being hit directly by a powerful magnitude-7 quake within four years, warns a study.

Tokyo: A new study is warning that the Tokyo region has a 70 per cent chance of being hit directly by a powerful magnitude-7 earthquake within four years.

The study by University of Tokyo seismologists bases the estimate on an increase in earthquake activity in the Tokyo region since last year`s March 11 disaster, when a magnitude-9 quake and subsequent tsunami about 230 kilometres northeast of the capital left nearly 20,000 people dead or missing. The group at the university`s earthquake research institute said the number of moderate quakes in the capital region measuring magnitude 3 or bigger surged to 343 in the six-month period after the March quake, up from 47 in the previous six months.

Based on a theory that the probability of bigger earthquakes rises in proportion to an increase in smaller quakes, the team calculated a 98 per cent likelihood of a magnitude 6.7 to 7.2 earthquake striking Tokyo over the next 30 years.

Stated differently, "When we ask when a probability of such a quake reaches 70 per cent, then we get a 70 per cent chance over the next four years," said Shinichi Sakai, a seismologist on the team.
A separate government study estimates that the chance of a magnitude-7 quake striking Tokyo is 70 per cent over the next 30 years. PTI