Ascension

Geography & Climate

Ascension is located in United Kingdom, within the Central Mid-Atlantic Rift Volcanic Province of the broader Atlantic Ocean Volcanic Regions. Situated at 7.95° S, 14.37° W in the Southern Hemisphere, the volcano lies within a tropical climate zone. With a summit elevation of 822 meters above sea level, Ascension is a moderately sized peak that remains accessible to hikers and researchers for much of the year. 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

Ascension 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 Ascension in United Kingdom 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

Ascension has 3 recorded eruptions in the geological database, spanning from 378 CE to 1508 CE. These eruptions span roughly 1,130 years of volcanic history.

GVP Reference Summary

Ascensión Island, just west of the Mid-Atlantic Ridge ~2,250 km E of the eastern-most point of Brazil, is the 12-km-diameter emergent summit of a stratovolcano that rises ~3,000 m above the seafloor. The isolated island has more than 100 youthful cones and lava domes, many aligned along two fissures. Basaltic rocks dominate on the island, but trachytic lava domes are also present, mostly on the eastern side. Two of the youngest lava flows were erupted from flank vents and reached the sea on the N and S coasts. Argon-Argon dating by Preece and others (2018) identified three eruptions within the past 2,000 years. No eruptive activity has occurred since it was visited on Ascensión Day in 1501 by the Portuguese navigator Joao da Nova.

— Smithsonian Institution, Global Volcanism Program