Seismic Tomography Experiment at Italy's Stromboli Volcano

Abstract

Stromboli Island, located in the southern Tyrrhenian Sea, is the emerged part (about 900 meters above sea level) of an approximately 3‐kilometer‐high stratovolcano. Its persistent Strombolian activity, documented for more than 2000 years, is sometimes interrupted by lava effusions or major explosions. Despite the number of recently published geophysical studies aimed at clarifying the volcano's eruption dynamics, the spatial extent and geometrical characteristics of its plumbing system remain poorly understood. In fact, knowledge of the inner structure and the zones of magma storage is limited to the upper few hundred meters of the volcanic edifice [Chouet et al., 2003; Mattia et al., 2004], and P and S wave velocity models are available only in restricted areas [Petrosino et al., 2002].

Two‐dimensional seismic attenuation images of Stromboli Island using active data

“…Recently, a P wave image of Stromboli Volcano in Southern Italy has been achieved with active data [ Castellano et al , ; Patané et al, in preparation, 2015]. We propose in the present work a complementary attenuation image of the same zone, achieved using the same active data set.…”

“…Then, Q i and Q s were calculated from equations and . In this estimation we assume p = 3 and v = 2.8 km/s derived from Castellano et al [] and considering the predominance of S waves in our seismograms as indicated by Yamamoto and Sato []. As the final step, we estimated the transport mean free path, l tr , and the absorption length, l i coefficients using the expressions l tr =3 d / v and l i = v / b , where d is the average diffusivity and b the average intrinsic‐attenuation coefficients obtained above.…”

“…More than 1500 offshore shots along linear or ring-shaped configuration profiles around Stromboli Volcano were fired (see Figure 1). The distance between each shot was around 250 m. Seismic signals were recorded inland by 33 three-component seismometers and additionally by 10 OBS (ocean bottom seismometers) [Castellano et al, 2008] (Figure 1), providing a data set composed of 21,953 waveforms. Data used in the present work were selected according to their high signal-to-noise ratio (higher than 2), avoiding possible influence of the persistent tremor of the island as a consequence of its volcanic activity [Castellano et al, 2008].…”

“…Then, Q i and Q s were calculated from equations (2) and (3). In this estimation we assume p = 3 and v = 2.8 km/s derived from Castellano et al [2008] and considering the predominance of S waves in our seismograms as indicated by Yamamoto and Sato [2010]. 5.…”

The shallow magma chamber of Stromboli Volcano (Italy)

“…In the frame of an INGV‐Italian Civil Defense project, part of which is aimed at better understanding the internal structure of the volcano and locating magma reservoirs, the first seismic tomography experiment was undertaken at Stromboli toward the end of 2006 [ Castellano et al ., ]. This in order to (i) better comprehend its activity, (ii) help predict the next eruption scenario, (iii) interpret the pattern of the expected precursory seismic activity and ground deformation field induced by magma upraise mechanisms in the shallow storage zones and along the feeding conduits, and (iv) better model edifice stability and associated hazards.…”