Fujikawa fault zone may cause M-8 earthquake

Divulgando: Daily Yomiuri Online


 The team, led by earthquake geologist Prof. Aiming Lin, discovered the fault zone measures
 about 40 kilometers long.

A team of researchers at Shizuoka University has   found the Fujikawa river fault zone, which extends west of Mt. Fuji, is 1.5 times longer than previously thought and could cause a magnitude-8 earthquake.

Previously, researchers believed the fault zone could cause up to a magnitude-7.2 quake. A magnitude-8 quake would have been possible only if the fault zone coincided with a Tokai Earthquake, which is predicted to occur along the Suruga (Nankai) Trough.

But Lin now says, "A quake caused by the fault zone alone could be of magnitude-8 ."

The fault zone is reportedly connected to the border of a tectonic plate that extends from the Suruga Trough to underground inland areas.

The fault zone crosses below the Tomei and Shin-Tomei expressways and the Tokaido Shinkansen line.

The government's Headquarters for Earthquake Research Promotion previously said the fault zone was about 26 kilometers long stretching from Fujinomiya, Shizuoka Prefecture, to the city of Shizuoka.

But Lin's team analyzed the geographical landscape to determine the fault zone actually stretches farther to Fuji-Kawaguchiko, a town in the prefecture more than 10 kilometers north of the previously believed tip of the zone.

Lin's team conducted drilling research to confirm this.

The latest research has also found a vertical undersea cliff two to three meters high, which is assumed to have been created in the past 1,000 years.

Lin said, "It's possible that the fault zone moved in conjunction with the Ansei Tokai Earthquake in 1854."

The government headquarters' long-term assessment indicated the probability of the fault zone causing a magnitude-8 earthquake in conjunction with the next Tokai Earthquake is as high as 18 percent in the next 30 years.

(Apr. 16, 2012)