Japan earthquake risk rises as fault zone evaluations are upgraded

Japan's Earthquake Research Promotion Headquarters has updated its long-term evaluation of active faults, significantly increasing the seismic risk for several regions. In Hyogo Prefecture, the probability of a magnitude 7.8 earthquake occurring within 30 years along the Rokko-Awashishima Fault Zone has been raised from “almost 0–1%” to “almost 0–7%,” elevating its risk status to the highest “S-rank.” This fault zone, which spans approximately 57km from Takarazuka through Kobe to northern Awaji Island, has not experienced a major earthquake of its characteristic scale since at least the 16th century.

In Oita Prefecture, experts warn of severe potential damage from the Median Tectonic Line Fault Zone. If an earthquake occurs here, seismic intensity of 7 is expected near the epicenter, with potential casualties reaching up to 30,000 people and over 88,000 buildings being destroyed or burned. While the 30-year probability for the Suo-nada Fault Zone is estimated at 2–4%, it shares the highest risk rank with the Hinagu Fault Zone, which triggered the major Kumamoto earthquake.

Across the Kinki region, the probability of a magnitude 6.8 or greater earthquake occurring within 30 years is estimated at 40–60% for the Kinki Triangular Zone and 50–60% for the entire Kinki area.