Shallow-conduit dynamics at Stromboli Volcano, Italy, imaged from waveform inversions

Abstract

Modelling of Very-Long-Period (VLP) seismic data recorded during explosive activity at Stromboli in 1997 provides an image of the uppermost 1 km of its volcanic plumbing system. Two distinct dyke-like conduit structures are identified, each representative of explosive eruptions from two different vents located near the northern and southern perimeters of the summit crater. Observed volumetric changes in the dykes are viewed as the result of a piston-like action of the magma associated with the disruption of a gas slug transiting through discontinuities in the dyke apertures. Accompanying these volumetric source components are single vertical forces resulting from an exchange of linear momentum between the source and the Earth. In the dyke system underlying the northern vent, a primary disruption site is observed at an elevation near 440 m where a bifurcation in the conduit occurs. At a depth of 80 m below sea level, a sharp corner in the conduit marks another location where the elastic response of the solid to the action of the upper source induces pressure and momentum changes in the magma. In the conduit underlying the southern vent, the junction of two inclined dykes with a sub-vertical dyke at 520 m elevation is a primary site of gas slug disruption, and another conduit corner 280 m below sea level represents a coupling location between the elastic response of the solid and fluid motion.

Recycled ejecta modulating Strombolian explosions

“…This widely accepted scenario is supported by a large body of literature focused on understanding the mechanism behind explosions at Stromboli volcano (Aeolian Islands, Italy) via, for example, interpretation of seismic and infrasonic data (e.g. Vergniolle et al 1996;Chouet et al 2003Chouet et al , 2008Marchetti and Ripepe 2005), experimental studies (e.g. James et al 2004James et al , 2006James et al , 2008Lane et al 2013), and field observations (e.g.…”

Numerical investigation of temporal changes in volcanic deformation caused by a gas slug ascent in the conduit

“…These data have improved our understanding of degassing processes and near surface magma dynamics on the basis of gas slug flow processes in the conduit (e.g., Ripepe et al, 2001;Ripepe and Marchetti, 2002;Chouet et al, 2003;Ripepe et al, 2007;Ripepe and Harris, 2008;Chouet et al, 2008;Marchetti et al, 2009). Chouet et al (2003) analyze very-long-period seismic signals associated with explosions at Stromboli.…”

Satellite radar data reveal short-term pre-explosive displacements and a complex conduit system at Volcán de Colima, Mexico

“…Therefore, detailed observations of processes in a volcano feeding system are mostly obtained at non-explosive volcanoes, or where complete seismic and geodetic monitoring was achieved. A constrained path the magma propagates through could only be described in a few of those cases, such as Stromboli (Chouet et al, 2008;Di Traglia et al, 2013), Mount Etna (Kahl et al, 2011), Piton de la Fournaise (Massin et al, 2011) or Hawaii (Chouet and Dawson, 2011). At explosive domebuilding volcanoes, the location of the conduit is more difficult to constrain.…”