Kasuga 2

Geography & Climate

Kasuga 2 is located in United States, within the Mariana Volcanic Arc of the broader Northwestern Pacific Volcanic Regions. Situated at 21.60° N, 143.64° E in the Northern Hemisphere, the volcano lies within a tropical climate zone. With an elevation of -274 meters — below sea level — Kasuga 2 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

Kasuga 2 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 United States near Kasuga 2, 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 basalt / picro-basalt, a dark, fine-grained volcanic rock that forms from rapidly cooling, low-viscosity lava. Basaltic eruptions tend to be less explosive and produce fluid lava flows that can travel long distances. While less immediately dangerous than explosive eruptions, basaltic lava flows can destroy structures and infrastructure in their path, and volcanic gases released during these eruptions can affect air quality over a wide area.

GVP Reference Summary

Kasuga 2, also referred to as Minami Kasuga (South Kasuga), is the central of three volcanoes forming the Kasuga seamount chain, which trends SSW from the volcanic front of the Izu-Marianas arc. It rises from about 3,000 m depth to within 170 m of the ocean surface. Two subsidiary cones are located low on the E flank. The morphology is more complex than Kasuga 1 to the north, and prominent ridges separate slopes of interspersed volcaniclastic and lava flow fields. Radiometric dating indicates an age of less than 8,000 years and probably less than 1,000 years; radium/thorium disequilibrium ratios suggest the flows may be only a few centuries old (Fryer et al., 1997). Active hydrothermal vents are located at the summit, at the base of summit ridges, and on the lower flanks.

— Smithsonian Institution, Global Volcanism Program