Page 410 - Caldera Volcanism Analysis, Modelling and Response

A New Uplift Episode at Campi Flegrei Caldera (Southern Italy) 385

Figure 8 (a) Theoretical curves of maximum horizontal/vertical ratios versus depth source
in the case of three ellipsoidal sources with di¡erent aspect ratio r (prolate ellipsoid, r ¼ 0.5;
sphere, r ¼ 1; oblate ellipsoid, r ¼ 2.0) embedded in an elastic half space with ring faults simulating
the geometry of Campi Flegrei caldera borders. Curves are obtained by an axial-symmetric
boundary element method, in which ring faults are described as conical surfaces on which shear
stress is null (Troise et al., 2003).The geometry and depth of ring faults is taken by Beauducel
et al. (2004), the radius is 2.7 km. From the ¢gure, it is apparent that ratios larger than about
0.55 are only attained with prolate and very shallow sources.Values of 0.30--0.35, as evidenced
in this study, are compatible with oblate sources, whose dependence on the depth is negligible.
(b) Expected maximum horizontal displacement as a function of distance from the source
calculated in the same cases shown in (a).