The Yanagase fault is a left-lateral strike-slip active fault trending N-S to NNW-SSE in northern Shiga Prefecture and Fukui Prefecture. We excavated seven trenches, namely N, Ma, Mb, Mc, Md, Ms and S trenches, near the Tsubakizaka Pass along the fault in order to know the timing of recent faulting events. An almost vertical fault plane is clearly observed on the walls of the Md, Ms and S trenches. The fault cuts the AT tephra layer (about 25ka) and is covered by the K-Ah tephra layer (about 7ka) in the S trench. According to the radiocarbon dates of samples from the trench walls, the timing of the latest faulting of the northern part of the fault is estimated to be 7000 to 7200 years ago. The previous trench study on this fault at about 4km south of this trench site, indicated that the fault ruptured about 600 years ago. This difference in the timing of the last faulting event may mean that the Yanagase fault is devided into at least two segments.
