Dual chamber-conduit models of non-linear dynamics 1 behaviour at Soufrière Hills Volcano, Montserrat 2 3 Oleg Melnik 1 , Antonio Costa 2 4 5 1 Institute of Mechanics, Moscow State University, Moscow, Russia, and Earth 6 Science Department, University of Bristol, Bristol, UK. 7 2 Environmental Systems Science Centre, University of Reading, Reading, UK, and 8 Istituto Nazionale di Geofisica e Vulcanologia, Naples, Italy. 9 10 To be submitted to the special volume “The Eruption of Soufriere Hills Volcano, 11 Montserrat from 2000 to 2010”, Editors: G. Wadge, R. Robertson, B. Voight, Memoir 12 of the Geological Society of London. 13 14 15 1. Introduction 16 17 Lava dome eruptions are typically characterized by large fluctuations in discharge rate 18 showing cyclic patterns of seismicity, ground deformation and volcanic activity. 19 Time-scales associated with these fluctuations range from hours-days (short-term 20 cycles) to years-decades (long-term cycles) with intermediate of 5 to 7 weeks as, for 21 example, observed on the Soufrière Hills Volcano (SHV), Montserrat. Concerning 22 short-term cycles, cyclic patterns of seismicity, ground deformation and volcanic 23 activity have been documented at Mount Pinatubo, Philippines, in 1991 and Soufrière 24 Hills Volcano, Montserrat, British West Indies, in 1996–2010. At SHV, periodicity in 25 seismicity and tilt ranged from ~3 to 30 hours (Voight et al., 1999; Odbert and 26 Wadge, 2010). 27 28 Several models have been proposed to explain the observed cyclicity in the last 29 decade. In both Denlinger and Hoblitt (1999) and Wylie et al. (1999) models the 30 lower part of the conduit acts like a capacitor that allows magma to be stored 31 temporally in order to release it during the intense phase of the eruption. Costa et al. 32