Geology topics

F. Sigmundsson

Publications and source records attributed to F. Sigmundsson.

2 recordsLinked to original sources

USGS2000

Comment on 'Volume of magma accumulation or withdrawal estimated from surface uplift or subsidence, with application to the 1960 collapse of Kilauea volcano' by P.T. Delaney and D.F. McTigue

In volcanoes that store a significant quantity of magma within a subsurface summit reservoir, such as Kilauea, bulk compression of stored magma is an important mode of deformation. Accumulation of magma is also accompanied by crustal deformation, usually manifested at the surface as uplift. These two modes of deformation - bulk compression of resident magma and deformation of the volcanic edifice - act in concert to accommodate the volume of newly added magma. During deflation, the processes reverse and reservoir magma undergoes bulk decompression, the chamber contracts, and the ground surface subsides. Because magma compression plays a role in creating subsurface volume of accommodate magma, magma budget estimates that are derived from surface uplift observations without consideration of magma compression will underestimate actual magma volume changes.

Hawai'i↗

USGS1998

Sources of crustal deformation associated with the Krafla, Iceland, eruption of September 1984

A decade-long plate-boundary rifting episode in northern Iceland ended with the September 1984 fissure eruption of Krafla volcano. We apply a nonlinear inversion method to geodetic data collected before and after the eruption to infer the location, geometry, and strengths of deformation sources associated with the eruption. The net outflow of magma from a 3-km-deep magma chamber beneath the Krafla caldera was 30−120× 10 6 m³. A similar volume of magma, 50−70×10 6 m³, was emplaced in a 1-meter-wide, ∼9-km-long dike extending from the surface to ∼7 km depth. Furthermore, at least 110×10 6 m³ of magma erupted. Accordingly, a surplus of magma must have been expelled from a second reservoir, the location of which, although uncertain, is likely to lie at depths greater than ∼5 km beneath Krafla volcano. It would be difficult to detect this deeper source because of the narrow aperture of the geodetic networks.

Geophysical Research Letters↗