The government's Headquarters for Earthquake Research Promotion held a task-force meeting on Feb. 21 and decided to add 16 locations in the Kanto, Chugoku, and Kyushu regions to the list of "major active faults" that could cause heavy damage.
The decision is expected to help with regional disaster prevention efforts as the newly listed active faults will be subject to priority research to be conducted by the government and other relevant entities. The latest addition has brought the total number of locations listed as "major active faults" across the country to 113.
Detailed research had been conducted in the three regions ahead of other areas since 2013 to check the possibility of earthquakes occurring in each of the three regions. The number of major active faults could increase further as the headquarters is also planning to conduct similar research in other regions.
The newly added major active faults include: the Minobu fault straddling Yamanashi and Shizuoka prefectures; the Okubo fault in Gunma and Tochigi prefectures; the Shikano-Yoshioka fault in Tottori Prefecture; the Saga plain northern fault zone; and the Midorikawa fault zone in Kumamoto Prefecture. The Shinji fault, that stretches from east to west about 2 kilometers south of Chugoku Electric Power Co.'s Shimane Nuclear Power Plant in Matsue, was also added to the list.
Since the 1995 Great Hanshin Earthquake, the headquarters had designated active faults with high seismicity stretching at least 20 kilometers that could cause earthquakes with a magnitude of 7 or higher as major active faults.
However, in response to a series of major tremors such as the 2004 Chuetsu earthquakes caused by faults that had not been listed as major active faults, the headquarters has conducted survey research on active faults including non-listed faults. As a result, even some of those faults that were considered to fall short of meeting the criteria for being called major active faults have been added to the list.
Kojin Wada, an official of the Earthquake and Disaster-Reduction Research Division at the Education, Culture, Sports, Science and Technology Ministry, said, "We expect that the general public's awareness of regional active faults is going to rise (with the latest addition to the list)."