The area features a 50km stretch of stable granite bedrock free of active fault lines. Since electrons and positrons are tiny invisible particles, a stable bedrock free of vibration is required when forcing them to collide accurately. Securing a stable 20km-50km length is also important. While not all areas are suitable for establishing the ILC, the Kitakami Highlands are one of the few places in the world with all the ideal conditions for establishing the ILC. The granite bedrock under the site covering Oshu and Ichinoseki cities stretches north to south in a gourd shape with its southern side called Senmaya granite and the northern side called Hitokabe granite. The narrowest part of the bedrock separates the two sides. According to the research conducted by Iwate in January 2012, the two granite bedrocks were completely connected. Also, both this research and another concrete geographical survey conducted with Tohoku University from December 2012 to the spring of 2013 concluded that the Kitakami Highlands were suitable for constructing the ILC. While the Tohoku region was seriously devastated by the Great East Japan Earthquake, its underground conditions were found to be very stable. A national observatory, the Esashi Earth Tides Station lies under the Kitakami Highland and their facility was not affected by the disaster at all.