April 24, 1771 Tsunami: Ryukyu Islands, Japan

Reference #414:

1771, April 24, about 8:00 local time. Validity 3. Following the shock on the Ryukyu Islands, a tsunami was observed with varying intensity at different places. On the Kume and Kerama Islands, 350 km northeast of the source of the earthquake, the tsunami was weak. On Yonaguni Island, about 180 km southwest of the source, and also on Hateruma and Iriomote Islands, the shores of which are protected

by coral reefs, there was no great destruction.

The islands of Ishigaki, Taketomi, Kuroshima, Aragusuku, Miyako, Irabu, Tarama, and Mizuna situated closest to the source (60-80 km), suffered greatly and there were many victims there.

The damage done by the waves on Ishigaki and Miyako Islands was about the same. However, the quantitative data on the height of the waves on these islands are contradictory. In the Japanese literature, the shaku (30.3 cm) and the jo (3.03 m) are usually used as a unit of measure of length. In all probability, the shaku and the jo were confused in a number of cases describing the tsunami. Miyako 10.5 m wave; Ishigaki 11.4 m wave.

The rise of water on Ishigaki Island can also be judged by the fact that a large stone (750 t) was transported to a height of 15 m. The three waves registered on both islands were observed for 2 hours; therefore one can assume that the period of the waves was about 30-40 minutes.

On Miyako and adjacent islands, 1,054 homes were washed away. A total of 2,548 people died, The villages situated on the Pacific coast of the islands of Miyako and Irabu suffered very heavily. In fact, at Miyakoku, Nissato, Uruka, and Tomosato homes, stone dikes and trees were washed away, and fields were scoured. On Tarama and Mizuna Islands, closest to the source, absolutely everything was washed away and the villages were leveled.

The tsunami approached Ishigaki Island and adjacent islands from the southeast, and the villages Maezato, Ohame, Miyara, Shiraho, Tozato, Ibaruma and Yasura, on the eastern coast, were completely washed away. More than half of the homes were washed away at the villages of Ishigaki, Shinkawa, Toyashiro, and Hirae, on the south side of the

islands.

There was similar destruction on Kuroshlma and Aragusuku

Islands; in all, 2,123 homes were washed away and 9,393 people died.

In all the Ryukyu Islands, this tsunami washed away and destroyed 3,137 homes and killed 11,941 people. There was an average of four dead for each home washed away on Ishigaki Island, and 2.5 dead for each home washed away on Miyako Island.

Reference #150:

85.4 m high tsunami at Miyara, in Ishigaki Is. Three large waves attacked Ishigaki Is. 3,237 houses washed away, 13,486 persons drowned.

Reference #79:

12 m wave height on Ishigaki and Miyako Islands.

Reference #132:

Japan, Isigaki-zima. Sea wave killed 9,400.