New Insights on Mt. Etna’s Crust and Relationship with the Regional Tectonic Framework from Joint Active and Passive P-Wave Seismic Tomography

Abstract

In the Central Mediterranean region, the production of chemically diverse volcanic products (e.g., those from Mt. Etna and the Aeolian Islands archipelago) testifies to the complexity of the tectonic and geodynamic setting. Despite the large number of studies that have focused on this area, the relationships among volcanism, tectonics, magma ascent, and geodynamic processes remain poorly understood. We present a tomographic inversion of P-wave velocity using active and passive sources. Seismic signals were recorded using both temporary on-land and ocean bottom seismometers and data from a permanent local seismic network consisting of 267 seismic stations. Active seismic signals were generated using air gun shots mounted on the Spanish Oceanographic Vessel 'Sarmiento de Gamboa'. Passive seismic sources were obtained from 452 local earthquakes recorded over a 4-month period. In total, 184,797 active P-phase and 11,802 passive P-phase first arrivals were inverted to provide three different velocity models. Our results include the first crustal seismic active tomography for the northern Sicily area, including the Peloritan-southern Calabria region

Dyke intrusion and stress-induced collapse of volcano flanks: The example of the 2018 event at Mt. Etna (Sicily, Italy)

“…in time and space) by using a comprehensive data set of P-and S-wave arrival times from past-decade seismicity. The present V P and V P /V S images have a high resolution from the surface down to 18 km depth, enhancing the imaging of previous models 19, [23][24][25] . The persistent seismicity permits to resolve time-lapse velocity images relative of the 2018 intrusive period (December 2018-January 2019).…”

“…The absence of clear low V P and high V P /V S anomalies argues against the presence of significant shallow magmatic volumes. A volume with such anomalies has been never identified beneath the volcano 19,[23][24][25] , while broad high attenuation anomalies have been interpreted as high temperature volumes, possibly constituting the principle paths of magma upraise around the HVB 31 . The tendency of seismicity to be absent in the deeper part of the HVB (Fig.…”

Coupling Between Magmatic Degassing and Volcanic Tremor in Basaltic Volcanism

“…Etna (Metrich et al, 2004;Spilliaert et al, 2006;Wallace and Edmonds, 2011). Convective overturn leads to permanent burial of degassed magma in the roots of the plumbing system, revealed as a voluminous plutonic body in seismic tomography observations (Patanè et al, 2006;Díaz-Moreno et al, 2018). We tentatively propose that periods of weak correlation between SO 2 flux and tremor, such as that observed in early 2007, are produced when magmatic overturn slows down, and degassing becomes dominated by permeable gas flow from depth.…”

A generic model for the shallow velocity structure of volcanoes

“…The resolution and depth of investigation of the resulting models depend on the methods used, on the type and wavelength of the seismic waves analyzed, on the geometry of the seismic network, on the distribution of the sources, and on the volume of data processed. The travel-time tomography is based on the inversion of arrival times of body-waves from passive or active sources (Chouet, 1996;Díaz-Moreno et al, 2017). Tomographic inversions provide meaningful estimates of seismic velocity only for those regions of the model space which are crossed by a sufficient number of ray segments with different orientations.…”