International Journal of Environmental Science and Development

Abstract—Ryukyu Archipelago is situated on Ryukyu Arc and consists of 6 major islands together with 55 islands of various sizes. Compared to the other parts of Japan, the documented seismic history of Ryukyu Archipelago is not well known. However, there are huge tsunami boulders, which definitely imply mega earthquakes in the vicinity of Ryukyu Archipelago. Furthermore, the archipelago experiences great typhoons every year compared with other parts of Japan. The Ryukyu limestone formation overlaying Shimajiri formation consisting of mudstone, sandstone and tuff cover a huge area in many islands of the archipelago. While large scale sinkholes and cliff failures observed in association with Ryukyu limestone formation, large scale landslides are commonly observed in Shimajiri formation as geotechnical disasters. It is shown that the risk of mega earthquakes, mega-tsunamis, large-scale geotechnical disasters are quite high in addition to super-typhoons in Ryukyu Archipelago.

Index Terms—Ryukyu archipelago, natural disaster, risk, earthquake, tsunami, landslides, typhoons.

Ömer Aydan is with University of the Ryukyus, Dept. of Civil Engineering, Nishihara, Okinawa, Japan; he is also with Disaster Prevention Research Center for Islands Regions, Nishihara, Okinawa, Japan (e-mail: aydan@tec.u-ryukyu.ac.jp).

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Cite: Ömer Aydan, "Some Thoughts on the Risk of Natural Disasters in Ryukyu Archipelago," International Journal of Environmental Science and Development vol. 9, no. 10, pp. 282-289, 2018.