1771 Great Yaeyama Tsunami

1771 Great Yaeyama Tsunami

Date	April 24, 1771 (1771-04-24)
Magnitude	7.2 M_s^[1]
Epicenter	24°00′N 124°18′E / 24.0°N 124.3°E / 24.0; 124.3Coordinates: 24°00′N 124°18′E / 24.0°N 124.3°E / 24.0; 124.3
Areas affected	Ryūkyū Kingdom: Ryukyu Islands
Tsunami	Yes
Casualties	13,486 deaths

The 1771 Great Yaeyama Tsunami (also called 明和の大津波, the Great Tsunami of Meiwa) was caused by the Yaeyama Great Earthquake at about 8 A.M. on April 24, 1771, south-southeast of Ishigaki Island, part of the former Ryūkyū Kingdom and now forming part of present-day Okinawa, Japan. According to records, 8,439 persons were killed on Ishigaki Island and 2,548 on Miyako Island.

Obi Rock on Shimoji island, Miyakojima. The rock is said to have been left by the tsunami.

Sawada beach on Shimoji island. The rocks are believed to be remnants of the tsunami

Earthquake analysis

According to the Japanese government publication Rika-Nenpyō (理科年表) or Chronological Scientific Tables,^[2] the epicenter was 40 km south-southeast of Ishigaki Island with a magnitude of 7.4. According to the Mamoru Nakamura Laboratory, University of the Ryukyus, the earthquake was due to the activity of the fault east of Ishigaki and it is estimated that the magnitude was 7.5.^[3] Further simulation led to the activity of faults in the Ryukyu oceanic trench and the magnitude was 8.0. Also, there is a hypothesis that claims the magnitude was 8.5.^[4]^[5] The depth was 6 kilometres (3.7 mi).^[6] This trench lies between the Philippine Sea Plate and the Eurasian Plate.

Damage

Earthquake

It is considered that the earthquake registered an intensity of 4(on the Japanese scale) in Yaeyama, and the damage by the earthquake was not as serious as the tsunami.

Tsunami

The dead and missing amounted to 12,000 people, and more than 2,000 houses were destroyed on Ishigaki and Miyakojima. Agriculture was severely damaged because of sea water invasion and the population decreased to about one third of what it was before the earthquake. On Ishigaki island, the wave was 40 to 80 meters high. There are many huge rocks believed to have been left by the earthquake. There was a legend that an islet disappeared, but this has never been verified.

Footnotes

↑ National Geophysical Data Center. "Comments for the Significant Earthquake". Retrieved 22 July 2011.
↑ "理科年表-オフィシャルサイト".
↑
↑ 阿部勝征(1999) 阿部勝征(1999): 遡上高を用いた津波マグニチュードMtの決定 -歴史津波への応用-, 地震, 第2輯, 第52巻, 369-377.
↑ 阿部勝征「津波地震とは何か」『月刊地球』Vol.25, No.5, p340
↑ http://seis.sci.u-ryukyu.ac.jp/hazard/EQ/1771yaeyama2/1771tsunami_2.html Meiwa earthquake was magnitude 8

Earthquakes in Japan

Historical	869 Sanriku 1293 Kamakura 1498 Nankai 1605 Nankai 1611 Sanriku 1703 Genroku 1707 Hōei 1771 Great Yaeyama 1792 Unzen 1854 Nankai 1854 Tōkai 1855 Edo 1858 Hietsu 1889 Kumamoto 1891 Mino–Owari 1894 Tokyo 1896 Sanriku

20th century	1911 Kikai Island 1923 Great Kantō 1927 Kita Tango 1930 North Izu 1933 Sanriku 1936 Miyagi 1943 Tottori 1944 Tōnankai 1945 Mikawa 1946 Nankai 1948 Fukui 1952 Hokkaido 1963 Kuril Islands 1964 Niigata 1968 Hyūga-nada 1968 Tokachi 1974 Izu Peninsula 1978 Miyagi 1983 Sea of Japan 1984 Otaki 1993 Hokkaidō 1994 offshore Sanriku 1995 Hanshin 1998 Ryukyu Islands 2000 Tottori

21st century	2001 Geiyo 2003 Hokkaidō 2004 Chūetsu 2005 Fukuoka 2005 Miyagi 2006 Kuril Islands 2007 Chūetsu 2007 Kuril Islands 2007 Noto 2008 Iwate–Miyagi 2009 Izu Islands 2009 Shizuoka 2010 Bonin Islands 2011 Tōhoku April 2011 Fukushima April 2011 Miyagi 2012 Chiba 2012 Kamaishi 2016 Kumamoto 2016 Fukushima

Related articles	Tōkai earthquakes Nankai megathrust earthquakes Kantō earthquakes

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