5:15 PM - 7:15 PM
[HDS10-P07] Consideration of tsunami inundation area in Toberi marsh, Hokkaido, Japan
Keywords:tsunami, tsunami deposit, great earthquake, Hokkaido, Kuril trench
M8-class interplate earthquakes occur repeatedly in the southern Kurile trench. Previous studies of the geological records indicate that tsunamis larger than those generated by M8-class earthquakes have repeatedly occurred in this trench. In the Pacific coast of eastern Hokkaido, prehistoric tsunami deposits have been reported, and the latest huge tsunami is considered to have occurred in the 17th century, and an earlier one around the 13th century (e.g., Nanayama et al., 2003). In this study, we compared the distribution of tsunami deposits and computed inundation areas in Toberi marsh in the Tokachi region, Hokkaido, Japan, to evaluate the magnitude of earthquakes that occurred in the 17th and around the 13th centuries, and discussed the variety of mechanisms of recurrent large earthquakes.
Previous studies have pointed out that the tsunami deposit distribution of the 17th century differed from that of around the 13th century. For example, at Oikamanai pond in the Tokachi region, tsunami deposits of the 17th century distributed further inland than those of the 13th century (Nanayama et al., 2002).
We surveyed the tsunami deposits to determine the inundation area by both tsunamis in Toberi marsh. To reproduce the distribution of the tsunami deposits, we compared the distribution area of the tsunami deposits with the computed inundation area. In previous studies by Satake et al. (2008) and Ioki and Tanioka (2016), the source of the 17th century earthquake is characterized by greater slip in the Tokachi segment than in the Nemuro segment. On the other hand, the inundation calculation results show that the source of the earthquake around the 13th century can explain the distribution of tsunami deposits in the case of larger slip in the Nemuro segment than in the Tokachi segment.
Previous studies have pointed out that the tsunami deposit distribution of the 17th century differed from that of around the 13th century. For example, at Oikamanai pond in the Tokachi region, tsunami deposits of the 17th century distributed further inland than those of the 13th century (Nanayama et al., 2002).
We surveyed the tsunami deposits to determine the inundation area by both tsunamis in Toberi marsh. To reproduce the distribution of the tsunami deposits, we compared the distribution area of the tsunami deposits with the computed inundation area. In previous studies by Satake et al. (2008) and Ioki and Tanioka (2016), the source of the 17th century earthquake is characterized by greater slip in the Tokachi segment than in the Nemuro segment. On the other hand, the inundation calculation results show that the source of the earthquake around the 13th century can explain the distribution of tsunami deposits in the case of larger slip in the Nemuro segment than in the Tokachi segment.