The June 14 earthquake in the Tohoku region underscores the need to strengthen studies of active faults for which quake-occurrence probability has not been evaluated. The 7.2-magnitude earthquake caused vibrations of upper 6 on the Japanese scale of 7 in Oshu, Iwate Prefecture, and in Kurihara, Miyagi Prefecture, and caused damage in Akita, Fukushima and Yamagata prefectures as well.
The education and science ministry is paying attention to the fact that the inland Tohoku quake occurred in the southern part of Iwate Prefecture, a place not clearly included in active fault zones analyzed by the government's earthquake studies committee. The committee has studied 110 active faults nationwide and calculated the probability of quake occurrence. But faults not covered by the studies caused the 2000 quake in the western part of Tottori Prefecture, the 2004 quake in the middle of Niigata Prefecture, and the 2007 quakes off Noto Peninsula in Ishikawa Prefecture and off Niigata Prefecture.
The Geographical Survey Institute has found through global positioning system-based observations that a spot in the mid-slope of the Kurikoma mountain system in Kurihara rose about 2.1 meters and moved about 1.5 meters in a southeast direction. The spot is a GPS fiducial point closest to the seismic center. The crustal movement is the largest since the institute started GPS-based observations in 1994.