Kasuga 1

Geography & Climate

Kasuga 1 is located in United States, within the Mariana Volcanic Arc of the broader Northwestern Pacific Volcanic Regions. Situated at 21.77° N, 143.71° E in the Northern Hemisphere, the volcano lies within a tropical climate zone. With an elevation of -598 meters — below sea level — Kasuga 1 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 1 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 1, 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 andesite / basaltic andesite, 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.

Eruption History Summary

Kasuga 1 has 2 recorded eruptions in the geological database, spanning from 1959 CE to 1975 CE. These eruptions span roughly 16 years of volcanic history. The most recent eruption in 1975 CE places this volcano within the modern era of volcanological observation.

GVP Reference Summary

Kasuga 1, the northernmost of three seamounts in the the Kasuga seamount chain SE of Fukujin, rises from a depth of 3,000 m to within about 600 m of the ocean surface. A series of flank vents are located low on the southern side of the edifice. The summit does not have a caldera or display hydrothermal activity, and is largely covered by volcaniclastics. Altered basaltic and andesitic rocks dredged from the summit suggest that it is the oldest of the three seamounts, although delicately preserved lava flow lobes and toes from a flank eruption suggest a very youthful age. It is listed as an active volcano by the Japan Meteorological Agency, and floating pumice attributed to a submarine eruption was seen south of it in the summer of 1959. Water discoloration from a possible submarine eruption was reported near the seamount in November 1975.

— Smithsonian Institution, Global Volcanism Program