Page 320 - Caldera Volcanism Analysis, Modelling and Response

Structural Development of Calderas 295

Kennedy et al. (2004) used a rubber bladder containing water (magma chamber
analogue) placed within sand (brittle crust analogue) to simulate collapse calderas

(Figure 7a). The length ratio between model and nature is L B10 5 and the
experiments last a few minutes. These models are characterised by a larger apparatus
than the previous ones (B1 m wide bladder). Consistently with what previously
observed (Roche et al., 2000; Acocella et al., 2000; Walter and Troll, 2001), after
flexure at surface, an inner outward dipping set of concentric reverse faults forms.

Figure 7 Experiments from Kennedy et al., 2004. (A) Adopted apparatus; (B) and (C)
modalities of collapse as a consequence of the di¡erent shape of the chamber--roof interface
(modi¢ed after Kennedy et al., 2004).