Fig. 8: Stress fields related to major drainage of magma.
From: Unexpected large eruptions from buoyant magma bodies within viscoelastic crust
a Amplitude of the minimum compressive stress, shown by the colour scale with negative values for tension, induced by combined buoyancy and under-pressure due to magma outflow (Δρgh + ΔPmagma body,flow) equal to −13.3 MPa, corresponding to the model presented for Bárðarbunga. Direction of maximum compressive stress (σ1) is represented by dashes. Most of the medium is put under tension with maximum effect immediately above the magma body. b Shear stress (amplitude of σ1–σ3; shown by the colour scale) for the same conditions as in a. The panels show that the stress field is favourable for caldera collapse initiation induced by the depressurisation.
