In the Joganji River basin, huge volume of sediment has been carried downstream and has formed the alluvial fan. The sediment runoff (erosion) volume is assumed to be 1.2 × 1011 m3, accounting by the hypsometric curve of the Joganji River, which indicates the amount corresponding to rise in the mountains of the upstream, 1 mm/year at average, since the start of the quaternary period. The fast-flowing Joganji River originating on the Tateyama Volcano slope was, until the end of the Edo Period (1607-1867), relatively stable as indicated by boat services operating from the river mouth to the fan apex. The Hietsu earthquake on April 9, 1858, caused numerous sediment disasters along the Atotsugawa fault system, some of the sediment movements built up landslide dams. Especially the catastrophic Tombi Landslide (Tombi-Kuzure) in the Tateyama Caldera, the upstream of the Joganji River, was the largest in the earthquake. The volume of the Tombi Landslide is estimated 103-127 million m3, one of the largest movements in the world calculated the volume difference of the configuration and the landform before the landslide based on wide-ranging historical data. The landslide dam broke twice – on April 23, 14 days after the quake and June 7, 59 days after it –, generating a large-scale outburst flood and sediment deposition on the Joganji River’s alluvial fan. Considering the carbon (14C) dating for the years 220-320 of pieces of wood sample at some deposits along the upstream of the Joganji River, it suggests that major sediment movement may have occurred in the Hietsu earthquake. But the years 720-940 suggest that major sediment movement may have occurred previously. Topographicaly, such a huge landslide is part of the mountain range erosion and disintegration process, making it important to be able to predict potential sediment movement’s scale and form accurately enough to minimize disaster and to better understand the overall landslide occurrence topographical changes.