A review of tectonic, elastic and visco-elastic models exploring the deformation patterns throughout the eruption of Soufrière Hills volcano on Montserrat, West Indies

Since the eruption began in 1995, Soufrière Hills volcano on Montserrat has been characterised by five phases of magma extrusion and corresponding pauses. Despite a lack eruptive surface activity since 2010, continues to show signs unrest form ongoing outgassing, inflation entire island Montserrat. Using numerical modelling, we compare set contrasting deformation models an attempt understand current state volcano, gauge its future potential. We apply suite including faults dykes, ellipsoidal source geometry all pauses covering history from 1995 through 2020. Based recent petrological evidence suggesting no injection depth after initial intrusion, test hypothesis that could be explained visco-elastic, crustal response intrusion without renewed pressurisation due injection. In contrast previous modelling attempts, focus conceptual elastic- with several visco-elastic taking temperature-dependent viscosity models, tectonic components, mass balance, compressibility outgassing data into account. explore wide parameter space Generalised Maxwell Rheology explain observed patterns, demonstrate realistic, depth-dependent distribution parameters does not allow interpretation signal any influx or further pressurisation. Within range large uncertainties attached model visco-elasticity reduces degree reservoir few percent. conclude at rate 0.10 0.57 m3/s is most likely explanation pattern also agreement balance considerations SO2 flux observations.