Sill intrusion in volcanic calderas and implications for vent opening.
Macedonio G., Giudicepietro F.
Observations and studies conducted in recent decades have shown that the most common cause of unrest at calderas is related to magmatic intrusions, in particular, to the intrusion of a sill at shallow depth. In general, the opening of a new eruptive vent can be regarded as a rock failure process caused by the stress produced by the intrusion itself. The intrusion process is mostly controlled by the injection rate, the mechanical response of the rock above the sill and magma viscosity. We find that the time variation of the stress in the rock is strongly controlled by the magma cooling rate.