Submarine Volcano NNE of Iriomotejima

Geography & Climate

Submarine Volcano NNE of Iriomotejima is located in Japan, within the Ryukyu Volcanic Arc of the broader Western Pacific Volcanic Regions. Situated at 24.57° N, 123.93° E in the Northern Hemisphere, the volcano lies within a subtropical climate zone. With an elevation of -200 meters — below sea level — Submarine Volcano NNE of Iriomotejima is a submarine or submerged volcanic feature. Submarine volcanoes make up the majority of Earth's volcanic activity, though most eruptions go unobserved beneath the ocean surface. The volcanic landform is characterized as a composite, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Submarine Volcano NNE of Iriomotejima sits in a subduction zone, where one tectonic plate dives beneath another, creating intense heat and pressure that generates magma. Subduction zones are responsible for many of the world's most explosive volcanoes and deadliest eruptions. For communities in Japan near Submarine Volcano NNE of Iriomotejima, this tectonic setting means the volcano is capable of producing powerful explosive eruptions, pyroclastic flows, and lahars that can threaten populated areas within tens of kilometers of the summit. The dominant rock type is rhyolite, a silica-rich volcanic rock associated with highly viscous magma. Rhyolitic eruptions can be extremely explosive and are responsible for some of the largest volcanic events in Earth's history, including supervolcanic caldera-forming eruptions. The high silica content traps dissolved gases, building enormous pressure that can lead to catastrophic explosive releases.

Eruption History Summary

Submarine Volcano NNE of Iriomotejima has 1 recorded eruption in the geological database, spanning from 1924 CE to 1924 CE. The most powerful recorded event was a cataclysmic eruption with ash columns reaching the stratosphere in 1924 CE, reaching VEI 4 on the Volcanic Explosivity Index. The most recent eruption in 1924 CE places this volcano within the modern era of volcanological observation.

Significance

With a maximum recorded VEI of 4, Submarine Volcano NNE of Iriomotejima has demonstrated the capacity for significant explosive eruptions that can impact regional aviation, agriculture, and communities tens of kilometers from the summit. VEI 4 eruptions produce ash columns reaching 15-25 kilometers into the atmosphere.

GVP Reference Summary

The southernmost Ryukyu Islands volcano is a shallow submarine volcano 20 km NNE of Iriomotejima island and 35 km WSW of the northern tip of the island of Ishigakishima in an area with an estimated depth of 200-300 m. A major submarine eruption on 31 October 1924 produced rhyolitic pumice rafts with an estimated volume of about 1 km3 that were carried by currents along both coasts of Japan as far north as Hokkaido. The largest pumice blocks exceeded 1 x 2 m in size, and the volume of ejecta places this poorly known eruption among the largest recorded in Japan.

— Smithsonian Institution, Global Volcanism Program