Teahitia

Geography & Climate

Teahitia is located in France, within the Society Islands Hotspot Volcano Group of the broader Southern Pacific Volcanic Regions. Situated at 17.56° S, 148.82° W in the Southern Hemisphere, the volcano lies within a tropical climate zone. With an elevation of -1,743 meters — below sea level — Teahitia 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

Teahitia is an intraplate volcano, meaning it formed away from any plate boundary. These volcanoes are often powered by hotspots — plumes of abnormally hot mantle material rising from deep within the Earth. Hotspot volcanoes like Teahitia tend to produce effusive eruptions with lava flows that can be relatively predictable, giving nearby communities in France more time to prepare. However, they can also produce explosive phases, particularly when magma interacts with groundwater. The dominant rock type is trachybasalt / tephrite basanite, 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

Teahitia has 4 recorded eruptions in the geological database, spanning from 1982 CE to 1985 CE. These eruptions span roughly 3 years of volcanic history. The most recent eruption in 1985 CE places this volcano within the modern era of volcanological observation.

GVP Reference Summary

Teahitia is a submarine volcano in the Society Islands whose summit reaches to within ~1,700 m of the surface, 40 km NE of the SE tip of Tahiti Island. Several seismic swarms in the 1980s included volcanic tremor that may have resulted from submarine eruptions (Talandier and Opal, 1984). Rocks dredged in 1986 "exploded" when they reached the surface, suggesting recent lava extrusion that had not yet had time to equilibrate with pressure and temperature conditions on the submerged flanks of the edifice. Two hydrothermal fields each about 400 x 1,000 m exhibiting low-temperature hydrothermal venting were discovered on the flanks during submersible dives in 1986 and 1989.

— Smithsonian Institution, Global Volcanism Program