Chapter 3 Dual-chamber-conduit models of non-linear dynamics behaviour at Soufrière Hills Volcano, Montserrat

Abstract

Abstract Modern geophysical data recorded during lava dome building eruptions indicate the presence of multiple connected magma storage regions. Most numerical models for lava dome eruptions assume a single magma chamber fed from below with a constant or prescribed time dependent influx rate and connected to the Earth surface through a conduit. Here we present a development of the model of extrusive eruptions considering a system made of two magma chambers located in elastic rocks and connected by a dyke between each other. We use locations and volumes of the magma chambers inferred for Soufrière Hills Volcano, Montserrat from ground deformation studies and seismic tomography. The model shows cyclic behaviour with a period that depends on the intensity of the influx rate, the volumes and shape of the two chambers and the degree of connectivity of the two reservoirs. For a weak connectivity the overpressure in the lower chamber stays nearly constant during the cycle and the influx of fresh magma into the shallow chamber is also nearly constant. For a strong connectivity between the chambers their overpressure increases or decreases during the cycle in a synchronous way.