Influence of pre-existing volcanic edifice geometry on caldera formation

6p.International audienceVolcanic edifice construction at the Earth's surface significantly modifies the stress field within the underlying crust with two main implications for caldera formation. First, tensile rupture at the Earth's surface is favored at the periphery, which enables ring fault formation. Second, edifice formation amplifies the amount of pressure decrease occurring within a magma reservoir before the eruption stops. Taking into account both of these effects, caldera formation can be initiated during a central eruption of a preexisting volcano even when assuming elastic behaviour for the surrounding crust. Providing the roof aspect ratio is small enough, conditions for caldera formation by reservoir withdrawal can be reached whatever the reservoir shape is. However ring fault initiation is easier for laterally elongated reservoirs. Citation: Pinel, V. (2011), Influence of pre-existing volcanic edifice geometry on caldera formation, Geophys. Res. Lett., 38, L11305, doi: 10.1029/2011GL047900