Control of the aspect ratio of the chamber roof on caldera formation during silicic eruptions
Article first published online: 21 NOV 2007
Copyright 2007 by the American Geophysical Union.
Geophysical Research Letters
Volume 34, Issue 22, November 2007
How to Cite
2007), Control of the aspect ratio of the chamber roof on caldera formation during silicic eruptions, Geophys. Res. Lett., 34, L22307, doi:10.1029/2007GL032059., and (
- Issue published online: 21 NOV 2007
- Article first published online: 21 NOV 2007
- Manuscript Accepted: 19 OCT 2007
- Manuscript Revised: 10 OCT 2007
- Manuscript Received: 26 SEP 2007
- caldera formation;
- analogue experiments;
 Several factors may control the development of a silicic caldera during an eruption: here we match previous studies of caldera forming eruptions with analogue experiments to consider the role of the aspect ratio (thickness/width) of the magma chamber roof. These data suggest that large silicic caldera formation is controlled by: (1) the availability of magma; (2) initial explosive eruption through a conduit connecting the reservoir and the surface; (3) fast depressurization of the reservoir; and (4) chamber roof collapse, with newly-formed fractures connecting the reservoir with the surface and creation of a continuous ring conduit feeding annular vents, capable of sustaining the eruption. The occurrence of the latter condition may depend upon the aspect ratio of the chamber roof: lower ratios (<1.6) form coherent collapse, ensuring connection from the chamber to the surface; higher ratios (>1.6) form incoherent collapse, which may hinder the continuation of the eruption after an initial partial emptying of the chamber. The aspect ratio of the chamber roof should therefore be considered as a further factor, capable of controlling the formation of large silicic calderas.