Southern EPR at 18.5°S (Segment I)

Geography & Climate

Southern EPR at 18.5°S (Segment I) is located in Undersea Features, within the Southern East Pacific Rise Volcanic Province of the broader Southern Pacific Volcanic Regions. Situated at 18.53° S, 113.42° W in the Southern Hemisphere, the volcano lies within a tropical climate zone. With an elevation of -2,600 meters — below sea level — Southern EPR at 18.5°S (Segment I) 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 cluster, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Southern EPR at 18.5°S (Segment I) 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 Southern EPR at 18.5°S (Segment I) in Undersea Features 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

Southern EPR at 18.5°S (Segment I) has 3 recorded eruptions in the geological database, spanning from 1620 CE to 1915 CE. These eruptions span roughly 295 years of volcanic history. The most recent eruption in 1915 CE places this volcano within the modern era of volcanological observation.

GVP Reference Summary

The narrow axial crest of Segment I of the Southern East Pacific Rise in some places is less than 50 m wide. An axial dome is located along the southern part of the segment. The largest lava flow field in this segment is the Animal Farm flow, named after a thriving low-temperature hydrothermal site discovered during a submersible expedition in 1993. The Animal Farm lava flow was dated by magnetic paleointensity measurements at about 1880-1950 CE, and older flows were dated by similar techniques to the 17th and 19th centuries.

— Smithsonian Institution, Global Volcanism Program