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A new model for the growth of basaltic shields based on deformation of Fernandina volcano, Galápagos Islands

Earth and Planetary Science Letters

By:
, , and
DOI: 10.1016/j.epsl.2013.07.016

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Abstract

Space-geodetic measurements of surface deformation produced by the most recent eruptions at Fernandina – the most frequently erupting volcano in the Galápagos Archipelago – reveal that all have initiated with the intrusion of subhorizontal sills from a shallow magma reservoir. This includes eruptions from fissures that are oriented both radially and circumferentially with respect to the summit caldera. A Synthetic Aperture Radar (SAR) image acquired 1–2 h before the start of a radial fissure eruption in 2009 captures one of these sills in the midst of its propagation toward the surface. Galápagos eruptive fissures of all orientations have previously been presumed to be fed by vertical dikes, and this assumption has guided models of the origin of the eruptive fissure geometry and overall development of the volcanoes. Our findings allow us to reinterpret the internal structure and evolution of Galápagos volcanoes and of similar basaltic shields. Furthermore, we note that stress changes generated by the emplacement of subhorizontal sills feeding one type of eruption may control the geometry of subsequent eruptive fissures. Specifically, circumferential fissures tend to open within areas uplifted by sill intrusions that initiated previous radial fissure eruptions. This mechanism provides a possible explanation for the pattern of eruptive fissures that characterizes all the western Galápagos volcanoes, as well as the alternation between radial and circumferential fissure eruptions at Fernandina. The same model suggests that the next eruption of Fernandina will be from a circumferential fissure in the area uplifted by the 2009 sill intrusion, just southwest of the caldera rim.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
A new model for the growth of basaltic shields based on deformation of Fernandina volcano, Galápagos Islands
Series title:
Earth and Planetary Science Letters
DOI:
10.1016/j.epsl.2013.07.016
Volume
377-378
Year Published:
2013
Language:
English
Publisher:
Elsevier
Contributing office(s):
Volcano Science Center
Description:
9 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Earth and Planetary Science Letters
First page:
358
Last page:
366
Country:
Ecuador
State:
Galápagos Islands
Other Geospatial:
Fernandina Volcano