OSAKA - The Japanese government has revised its assessment of active faults across the Kinki region for the first time in about 20 years, increasing the number of fault zones considered at the highest level of concern for earthquakes of magnitude 6.8 or greater from three to eight.
Unlike earthquakes along undersea plate boundaries such as the Nankai Trough, which can produce both severe shaking and tsunamis, earthquakes occurring directly beneath populated areas along active faults can generate short, violent shaking capable of collapsing homes and buildings.
The government's Earthquake Research Committee classifies active faults into four risk categories based on the probability of a magnitude 6.8 or stronger earthquake occurring within the next 30 years.
Fault zones with a probability of 3% or higher are designated S rank, the category regarded as requiring the greatest vigilance.
The Hinagu Fault Zone, which caused the Kumamoto earthquake on July 28, had also been classified as S rank before the disaster.
The latest assessment covers active faults across two prefectures and nine other prefectural-level jurisdictions in the Kinki region and represents the first major revision of the area's earthquake risk in roughly two decades.
Under the revised assessment, the number of S-rank active fault zones in the region has increased from three to eight.
A government earthquake researcher said the Kinki region has one of the highest concentrations of active faults in Japan and that many of them are considered highly active.
The assessment also includes sections associated with the fault system involved in the Great Hanshin-Awaji Earthquake that did not rupture during the 1995 disaster. Those remaining sections are now assessed as having a probability of 3% or higher of producing an earthquake within the next 30 years.
The revised findings highlight the continuing threat posed by inland active faults beneath and around densely populated parts of the Kinki region, where strong earthquakes can strike with intense shaking close to the surface.
Source: KTV NEWS
