1999 年 52 巻 1 号 p. 43-50
The Noto Peninsula coast has been suffered from the tsunamis originated along the eastern margin of the Japan Sea. According to the old documents, the 1833 Yamagata-Oki tsunami reached 5.3m at Wajima (tip of Noto Peninsula), and killed 47 persons. Inundation heights of the 1964 Niigata, 1983 Nihonkai-Chubu and 1993 SW. Hokkaido tsunamis were 2-4m at Wajima and its neighboring area. These tsunami heights are more than 2-3.5 times larger than the ones expected from the average tsunami magnitude. Based on the refraction diagrams and the shoaling-refraction factors around the peninsula, amplification factors estimated by the Green's formula are 3.0-4.0 at the north coast, 1.5 at the west coast and 1.0 at the east coast. The distribution patterns of the calculated factors nearly agree with those of the inundation heights for each tsunami. In case of the 1964 Niigata tsunami having the period of about 20min, the seishe of Nanao Bay (east side of peninsula) may be excited, because the maximum wave occurred 2.7 hour late from the initial wave. Tsunamis generated off Yamagata and SW. Niigata are strongly affected by the shoaling-refraction.