Page 322 - Caldera Volcanism Analysis, Modelling and Response

Structural Development of Calderas 297

Figure 8 Experiments with regional stress: Acocella et al., 2004. (a) Explanation for the
ellipticity of the caldera considering the deformation pattern across two orthogonal
sections (b and c) (modi¢ed after Acocella et al., 2004).

This variation is induced by the imposed regional extension, which increases the dip
of the maximum direction of compression s1. The opposite occurs under regional
compression, where the mean dip of the reverse faults lowers to B501, as due to the
increase in the dip of the minimum direction of compression s3(Figure 9d).