Tectonic landforms and co-seismic uplift in the Southwestern Coastal Area of the Noto Peninsula, Central Japan

Abstract

To clarify the cause of the crustal uplift in the southwestern coastal area of the Noto Peninsula, central Japan, we investigated tectonic landforms along the coast. The marine terrace surfaces are classified into HI, H2, H3, Ml, M2, and A surfaces in descending order. The rocky coastal area is fringed by emerged wave-cut benches. The H1-H4 surfaces covered by red-weathering crust are older than the Ml surface. The Ml surface covered by SK tephra (110-115ka) is correlated with that formed in MIS 5e. The A surface is a Holocene wave-cut bench. The progressively greater slopes of successively higher marine terrace surfaces clearly record continual crustal tilting to the south. To the north, the Togikawa-nangan Fault dislocates them. The amount of vertical displacement has been ca. 30 m since MIS 5e. It seems that the fault has been becoming increasingly active since MIS 5e. As emerged wave-cut benches are indicative of episodic and abrupt relative uplifts, a paired marine terrace and bench strongly suggests that the uplift of the coastal area has been co-seismic. These tectonic features have been convincingly shown to be due to the activity of a southeast-to-east dipping, active reverse fault. The Togikawa-nangan Fault may extend to the submarine active fault about 3 to 4 km west of the coast.