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.

Updated: Jan 24, 2012, 18:25 PM IST

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.