高知県下の上韮生川断層の左横すべり変位量

The NE-trending Kaminirogawa fault is one of the major left-lateral strike-slip faults in the Outer Zone of Southwest Japan. The Odochi-Kahoku Area in Kochi Prefecture was mapped and the trace of the fault was clarified. The Cretaceous Formation of the Chichibu Terrain is displaced southwestward, and is in contact with the Shimanto Supergroup. The limestone-dominated Formation of the Sambosan Group is separately distributed in four blocks, produced by the NW-trending Odochi fault and the crosscutting Kaminirogawa fault.
Left-lateral strike-slip displacement of the Kaminirogawa fault is estimated by using three geological markers, taking vertical displacement of 0.5-1.0 km into consideration. The strike-slip displacement is 10.3-11.3 km, 10.4 km and 8.6-10.0 km, decreasing from NE to SW. The values are larger than those clarified in Tokushima Prefecture. The Kaminirogawa fault was fonned in Miocene-Pliocene times after the major strike swinging of the Chichibu-Sambosan and Shimanto Terrains.