2011 Honshu earthquake has increased the chance of a large earthquake hitting Kanto Plain area, encompassing Tokyo, over the next 30 years: AIR

The Magnitude-9 Honshu earthquake that struck Japan on Mar. 11, 2011 has transferred stress to neighboring faults underlying Kanto Plain, a 17,000-square-kilomtre area that includes Tokyo and five other large prefectures, and Sagami Trough, where a Magnitude 7.9 earthquake struck in 1923, according to new research published by Catastrophe modeler AIR Worldwide.

“AIR’s analysis indicates that the 30-year rupture probability of [Magnitude-6.7 or greater] earthquakes in the Kanto Plain, for example, may have increased from 72% to between 81% and 93%,” AIR said about the release of its report, Understanding Earthquake Risk in Japan Following the Tohoku-Oki Earthquake of March 11, 2011

However, the possibility of a Magnitude-7 or greater earthquake hitting the Boso Peninsula, the coastline facing Tokyo, sometime over the next four years is considerably less likely than reported, AIR adds.

In a press release, AIR notes a study published last fall by researchers at Tokyo University’s Earthquake Research Institute (ERI) estimated a 70% chance of a Magnitude-7 earthquake striking in the vicinity of the Boso Peninsula within the next four years.

AIR’s findings suggest the risk of an earthquake hitting the Tokyo area sometime over the next four years is more on the order of “between 23% and 28% at most, significantly lower than the one produced by the researchers at ERI.”

AIR’s full report can be found at:

http://www.air-worldwide.com/download.aspx?id=21680