Ryukyu Islands

(also Nansei-Shoto), an archipelago in Japan, between the islands of Kyushu and Taiwan. The Ryu-kyus separate the East China Sea from the open Pacific Ocean and stretch in an arc from northeast to southwest for approximately 1,200 km. The archipelago consists of six groups of islands—Osumi, Tokara, Amami, Okinawa, Miyako, and Yae-yama; the last two groups are often called Sakishima. The six groups include 98 islands, with a total area of about 4,800 sq km. (In Japanese sources the name “Ryukyus” often refers only to the middle and southwestern segments of the island arc—that is, to 55 islands, with a total area of 2,400 sq km.) The largest islands are Okinawa and Amami-o-shima. Population, 1.2 million (1970, estimate).

The southeastern group of islands is composed primarily of Mesocenozoic karstified limestones. In the axial zone the Paleozoic folded basement often crops out at the surface. Igneous rocks are common in the northwest; there are three active and several extinct volcanoes. Plateaus, low mountains (300–500 m), and low coastal terraces dominate the relief. The highest point is 1,935 m, on the island of Yaku. South of 29°N lat., coral reefs stretch along the shores in some places. The islands have deposits of phosphorites and hard coal.

The northern islands have a subtropical climate. The southern ones have a tropical monsoon climate, with about 2,000 to 3,500 mm of precipitation a year and with frequent typhoons in August and September. The mean January temperature is 14°–18°C; the mean July temperature is 27°-28°C. The mountain slopes of the southern islands are covered in places by tropical forests of palms and orchids. On the northern islands, forests of camellias, magnolias, camphor trees, and oaks remain.

Economic activities include the cultivation of rice, sweet potatoes, and sugarcane, fishing, and the production of silk fabrics and lacquer ware. The principal city is Naha, on the island of Okinawa.