Structure and eruptive mechanisms at Surtsey Volcano, Iceland

Geological Magazine
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Abstract

Glassy basalt tuff was the primary material cored in 1979 from a 181 m deep drill hole on the east tuff ring of Surtsey volcano. Despite the fact that the hole extends 122 m below sea level all the core is similar to the exposed tephra composing the two tuff rings of the island. The tuff includes abundant accretionary lapilli and tuff vesicles, indicating that it was all deposited subaerially. During the growth of the tuff rings, repeated hydromagmatic explosion cycles began with a series of intermittent tephra-finger explosions leading up to continuous uprush explosions which lasted for several minutes to several hours. This nozzle-like continuous activity produced eruption columns 100–250 m in diameter and 500–2000 m in height which probably quarried several hundred metres below the ground surface. The continuous-uprush explosion type provides a reasonable mechanism to excavate a diatreme from the top down. During construction of the tuff rings, concentric faults repeatedly downdropped a funnel-like structure (400–800 m in diameter) several hundred metres, thus accounting for the presence of subaerially deposited tephra in the drill core far beneath sea level. Ring dykes later intruded upward along these faults and fed small lava flows. Heat in the surface tephra probably originated primarily from these shallow intrusions.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Structure and eruptive mechanisms at Surtsey Volcano, Iceland
Series title Geological Magazine
DOI 10.1017/S0016756800032052
Volume 122
Issue 6
Year Published 1985
Language English
Publisher Cambridge University Press
Description 13 p.
First page 649
Last page 661
Country Iceland
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