Abstract

This paper combines the temporal model of caldera formation presented by Robert Smith and Roy Bailey in 1968 with recent volcanological concepts. Field examples, experimental models and theoretical studies are synthesized to illustrate the process of caldera collapse conceptually as a series of stages of eruption and deformation. During each stage, physical changes occur at the surface, within the underlying magma chamber, and within the subsiding block or blocks that lie between the surface and the top of the magma chamber. The stages are as follows: 1) magma chamber intrusion, 2) initial eruption, down sagging and the on set of subsidence, 3) main subsidence and eruption phase, 4) peripheral extension and eruption quiescence, 5) continued eruption, subsidence and change of eruptive style, and 6) resurgence and extrusion of lava domes and flows. These stages may then be repeated as a subsequent caldera cycle. Every caldera has an individual history and may deform in a different manner at each stage. The paper outlines how these stages can give rise to different caldera types. Sommaire Le présent article fait état des concepts et des publications les plus importantes en matière d'effondrement des caldeiras. On y présente également une vue d'ensemble des différents types de caldeira, leurs caractéristiques illustrées d'exemples concrets, ainsi qu'un glossaire de la nomenclature afférente. Nous traiterons des concepts de piston, d'affaissement, d'effondrement concentrique par paliers, ainsi que de caldeiras de style chaotique, de fossé tectonique et fragmentaire. Il semblent que certaines caldeiras soient le résultat d'une combinaison de style. Nous considérons les interactions complexes de variables qui déterminent la structure et la morphologie des caldeiras et en conditionnent le style.