Iwo Jima - Geographic Features

Geographic Features

The island has an approximate area of 21 km2 (8 sq mi). The most prominent feature is Mount Suribachi on the southern tip, a vent that is thought to be dormant and is 161 m (528 ft) high. Named after a Japanese grinding bowl, the summit of Mount Suribachi is the highest point on the island. Iwo Jima is unusually flat and featureless for a volcanic island. Suribachi is the only obvious volcanic feature, as it is only the resurgent dome (raised centre) of a larger submerged volcanic caldera.

Captain Cook's surveying crew in 1776 to 1779 landed on a beach which is now 40 m (131 ft) above sea level due to volcanic uplifting. Such uplifting occurs on the island at a varying rate of between 100 and 800 mm (3.9 and 31 in) per year, with an average rate of 200 mm (8 in) per year.

Forty-three nautical miles (50 mi, 80 km) north of the island is North Iwo Jima (北硫黄島, Kita-Iō-tō?, literally: "North Sulfur Island") and 32 nautical miles (37 mi; 59 km) south lies South Iwo Jima (南硫黄島, Minami-Iō-tō?, "South Sulfur Island"), with the three islands making up the Volcano Islands group of the Ogasawara Islands. Just south of Minami-Iō-jima are the Mariana Islands.

Iwo Jima has a history of minor volcanic activity a few times per year (fumaroles, and their resultant discolored patches of seawater nearby), but so far no sign of a big eruption coming. The latest activity was in May 2012 (fumaroles and discolored patches of seawater).