Figure 3
From: Contrasting catastrophic eruptions predicted by different intrusion and collapse scenarios
Structural evolution of deformation pattern 2. t0: stage before beginning the experiment; t1 and t2: stages at minutes 5 and 10 respectively. (a) X-ray cross-sections of the volcano (see b for sections location) of a representative experiment (Experiment 16: see Table 1). Faults are imaged as darker linear trends and syrup intrusion as a homogeneous dark grey area. Note at t1 image the development of a curved (i.e. listric) convex upward fault from the intrusive body towards the cone middle flank surface. At t2 image that fault has reached the cone surface and a new inward-dipping planar fault is developed from near the summit zone. (b) Sketched structural interpretation in cross-sections and map-view of the main deformation features common at experiments showing this deformation pattern (see text for an explanation). f1, f2: faults, in chronological order. Dashed lines: diffuse shear zones. Grey areas: changes at volcano topography (dark grey: subsidence; light grey: bulging). Black zones: magma bodies. Large arrows: movement of the volcano blocks (i.e., subsidence, lateral displacement or tilting). Thin arrows: relative movement along fault planes and basal shear zones. Circle: tube location. Dots: volcano centre. (c) Map-views showing the variation of the cone topography detected by MDCT between times t1 and t0 (t1-t0), and between t2 and t1 (t2-t1), over a shaded relief image of the cone. Contour interval: 1 mm. Colour scale at right. Note the slight subsidence of the summit zone together with the outward displacement of the lower flank downwards the first fault.
