Southern EPR at 17.5°S (Segment K)

Geography & Climate

Southern EPR at 17.5°S (Segment K) is located in Undersea Features, within the Southern East Pacific Rise Volcanic Province of the broader Southern Pacific Volcanic Regions. Situated at 17.44° S, 113.21° W in the Southern Hemisphere, the volcano lies within a tropical climate zone. With an elevation of -2,566 meters — below sea level — Southern EPR at 17.5°S (Segment K) 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 17.5°S (Segment K) 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 17.5°S (Segment K) 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 17.5°S (Segment K) has 5 recorded eruptions in the geological database, spanning from 1625 CE to 1990 CE. This eruption frequency indicates a moderately active volcanic system with periodic reawakenings. The most recent eruption in 1990 CE places this volcano within the modern era of volcanological observation.

Significance

With 5 recorded eruptions on file, Southern EPR at 17.5°S (Segment K) has enough documented activity to help scientists identify patterns in its eruptive behavior. Given its recent activity, Southern EPR at 17.5°S (Segment K) is closely monitored by geological survey organizations to provide early warning of future unrest.

GVP Reference Summary

Lava flows from a very recent eruption were observed in 1994 along segment K of the southern East Pacific Rise. This segment of the mid-ocean ridge north of the Easter microplate displays the broadest cross-sectional area and the shallowest depth (2,566 m) of the southern East Pacific Rise between 13°40' and 18°30'S. Glassy, unsedimented lava flows on the 17.5°S segment of the East Pacific Rise were considered, from biological observations and chemical analyses of the plume and vent fluids, to have been erupted within 2-3 years of a November-December 1993 plume survey. Lava was erupted along two segments, a 4-km-long flow at the southern site and a 5-10 km flow at the northern site. Numerous low- and high-temperature hydrothermal vents are active along this segment of the ridge.

— Smithsonian Institution, Global Volcanism Program