Boomerang Seamount

Geography & Climate

Boomerang Seamount is located in France, within the Amsterdam-St. Paul Hotspot Volcano Group of the broader Somalian-Antarctic Volcanic Regions. Situated at 37.72° S, 77.82° E in the Southern Hemisphere, the volcano lies within a temperate climate zone. With an elevation of -650 meters — below sea level — Boomerang Seamount 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 caldera, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Boomerang Seamount is situated along a rift zone, where tectonic plates are pulling apart. As the crust thins and fractures, magma rises to fill the gap, creating volcanic activity. Rift volcanism typically produces more fluid lava flows rather than explosive blasts, which means communities near Boomerang Seamount in France generally face slower-moving hazards like lava flows and ground fissures rather than sudden pyroclastic events. However, rift volcanoes can still generate significant ash emissions and gas releases that affect local air quality. 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.

Eruption History Summary

Boomerang Seamount has 1 recorded eruption in the geological database, spanning from 1995 CE to 1995 CE. The most recent eruption in 1995 CE places this volcano within the modern era of volcanological observation.

GVP Reference Summary

Boomerang Seamount, an active submarine volcano 18 km NE of Amsterdam Island, was first discovered during a bathymetric survey in 1996. It rises to within 650 m of the ocean surface and has a 2-km-wide summit caldera that is 200 m deep. Rift zones that extend to the SE and N give it an arcuate shape. A basaltic volcano, it lies along the axis of the Southeast Indian Ridge and marks the site of the Amsterdam-St. Paul hotspot. This hotspot may have been the source of the Ninetyeast Ridge submarine volcanoes on the Australian Plate prior to its "capture" by the Southeast Indian Ridge, after which volcanism was restricted to the Antarctic Plate. Very short half-life radionuclide dating of fresh volcanic glass samples recovered during the 1996 expedition indicated that it had erupted only about 5 months earlier (Johnson et al., 2000). Water column temperature anomalies above the seamount suggest the presence of hydrothermal activity within the caldera.

— Smithsonian Institution, Global Volcanism Program