1771 Great Yaeyama Tsunami

1771 Great Yaeyama Tsunami

Date	April 24, 1771 (1771-04-24)
Magnitude	7.2 Ms[1]
Countries or regions	Japan: 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, Okinawa, Japan. 8439 persons were recorded as being killed on Ishigaki Island and 2548 on Miyakojima Island.

Contents 1 Chronological Scientific Tables 2 View of the Mamoru Nakamura Laboratory, University of the Ryukyus 3 The earthquake 4 Another great tsunami 5 Damage 6 References 7 Footnotes

Chronological Scientific Tables

• The National Astronomical Observatory of Japan published the Rika-Nenpyō　or Chronological Scientific Tables,^[2] and according to it, the epicenter was 40 km south south east of Ishigaki Island, and magnitude was 7.4. However, these data cannot explain the violent tsunami.

View of the Mamoru Nakamura Laboratory, University of the Ryukyus

• He thought that the earthquake was due to the activity of the Fault (geology) east of Ishigaki and estimated that the magnitude was 7.5. ^[3] Further simulation led to the activity of Fault (geology) in the Ryukyu Oceanic trench and the magnitude was 8. The depth was 6 kilometres (3.7 mi). ^[4]

The earthquake

• By the Plate tectonics, this earthquake is believed to be an oceanic trench type of earthquake occurring between the Philippine Sea Plate and the Eurasian Plate.

Another great tsunami

Damage

• The dead and missing amounted to 12,000, and the destroyed houses to more than 2000 in Ishigaki and Miyakojima. Agriculture was severely damaged because of sea water invasion and the population in the Meiji era decreased to about one third of what it had been before the earthquake. On Ishigaki island, the wave was 40 meters high and the wave reached a height of 80 meters. There are many huge rocks believed to be left by the earthquake. There was a legend that an islet disappeared, but this has never been verified.

References

• Yaeyama Great Earthquake in Japanese

Footnotes

1. ^ National Geophysical Data Center. "Comments for the Significant Earthquake". http://www.ngdc.noaa.gov/nndc/struts/results?eq_0=1405&t=101650&s=13&d=22,26,13,12&nd=display. Retrieved 22 July 2011. 
2. ^ http://www.rikanenpyo.jp/
3. ^ [1]
4. ^ http://seis.sci.u-ryukyu.ac.jp/hazard/EQ/1771yaeyama2/1771tsunami_2.html Meiwa earthquake was magnitude 8