The Sanshukaido fault is located at the southern part of the Ina - Valley fault zone, trending in the NE - SW direction and accompanying late Quaternary activity. In this study, we excavated a trench across the Sanshukaido fault at Samuhara site in order to reveal the timing of recent faulting events. On the trench walls across the Sanshukaido fault, a layer of humic soil is displaced by a low angle reverse fault. This excavation revealed evidences for the latest and the penultimate events associated with at least two surface-ruptures. The latest event might be occurred sometimes after AD1408, and the penultimate event occurred between BC6587 and BC1753. Recurrence interval of this fault is estimated to be 3160-8590 years.
