Formation of curvature of the Median Tectonic Line inferred from high-precision rock magnetic measurements

对本州中部中新世沉积岩进行了古地磁测量。样品采集自Ichishi(Mie Pref.)、Morozaki(Aichi Pref.)和Tomikusa(Nagano Pref.)并对确定的古地磁方向进行了统计分析，以评价本州中部与伊豆-小川弧碰撞引起的地壳形变。根据古地磁造山斜测试，认为日本本州岛中部最突出的断裂--中线构造曲线在1800万~1700万年前为直线。

Paleomagnetic measurements were conducted on Miocene sedimentary rocks from central Honshu. Samples were collected from the Ichishi (Mie Pref.), Morozaki (Aichi Pref.) and Tomikusa (Nagano Pref.) groups, and the paleomagnetic directions determined for these groups were statistically analyzed in order to evaluate the crustal deformation caused by collision between central Honshu and the Izu-Ogasawara arc. Based on a paleomagnetic orocline test, it is concluded that the curved Median Tectonic Line in central Honshu, the most prominent fault in Japan, was straight 18-17 million years ago.