Abstract
We discovered two fault outcrops at the eastern part of the Atotsugawa fault in Sako, Hida City. Radiocarbon dating of the samples from the fluvial strata of the outcrops indicates 100±30 yrs BP and 140±30 yrs BP. Since the fault plane clearly cut the strata, the latest faulting event occurred after these ages. This event is correlative with the AD1858 Hietsu earthquake, on the basis of the historical record of earthquakes in Japan. From the results of previous studies and this study, it is considered that the faulting occurred in all the section of the Atotsugawa fault during the latest event.
Because the timing and interval of the faulting events which occurred less than 10,000 years ago are almost compatible between the western and eastern parts of the Atotsugawa fault, it is probable that the older faulting events also occurred at once in all the parts of the fault.
