Body wave attenuation heralds incoming eruptions at Mount Etna

How fast and foreseeable is the magma ascent is one of the most impellent and unanswered issues of volcanology. The velocity of the magma upwelling depends on the local conditions of the volcanic conduit and rheology of the magma (Scandone et al., 2007). During magma emplacement in the shallow crust, transient variations of physical properties underneath active volcanoes are expected and in a few cases observed (Patanè et al., 2006). The predictability of such changes strongly depends on how fast this process is, compared to our ability to handle geophysical data and consistently resolve transient anomalies in the physical properties of the medium. Mt. Etna is a perfect natural laboratory to investigate such issues, due to the almost continuous magmatic activity and the high quality of seismologic and geodetic data. Here we show, for the first time, that seismic attenuation of local earthquakes strongly increases due to the emplacement of magma within the crust, forecasting an incipient eruption at Mt. Etna.

Berckemer, H., Kampfmann, W., Aulbach, E., and Schmeling, H., 1982, Shear modulus and Q of forsterite and dunite near partial melting from forced-oscillation experiments: Phys. Earth Planet. Inter., v. 29, p. 30– 41.
Bonaccorso, A., Aloisi, M., and Mattia, M., 2002, Dike emplacement forerunning the Etna July 2001 eruption modelled through continuous tilt and GPS data: Geophys. Res. Lett., v. 29 (13), 1624, doi: 10.1029/2001GL014397.
Bonforte, A., Carbone, D., Greco, F., and Palano, M., 2007, Intrusive mechanism of the 2002 NE-rift eruption at Mt. Etna (Italy) modelled using GPS and gravity data: Geophys. J. Int., v. 169, p. 339-347, doi: 10.1111/j.1365-246X.2006.03249.x.
De Gori, P., Chiarabba, C., and Patanè D., 2005, QP structure of Mount Etna: constraints for the physics of the plumbing system: J. Geophys. Res., v. 110, B05303, doi: 10.1029/2003JB002875.
Eberhart-Phillips, D., and Chadwick, M., 2002, Three-dimensional attenuation model of the shallow Hikurangi subduction zone in the Raukumara peninsula, New Zealand: J. Geophys. Res. v. 107(B2), 2033, doi: 10.1029/2000JB000046.
Evans, J.R. and Zucca, J.J, 1993, Active source, high-resolution (NeHT) tomography: Velocity and Q, in Iyer, H., and Hirahara, K., eds., Seismic Tomography: Theory and Practice: Boca Raton, Fla, CRC Press, p. 695– 732.
Kampfmann, W., and Berckemer, H., 1985, High temperature experiments on the elastic and anelastic behaviour of magmatic rocks: Phys. Earth Planet. Inter., v. 40, p. 223–247.
Lees, J., 2007, Seismic tomography of magmatic systems: J. Volcanol. Geotherm. Res., v. 167, p. 37–56.
Michelini, A., and McEvilly, T.V., 1991, Seismological studies at Parkfields I: Simultaneous inversions for velocity structure and hypocenters using a cubic B-splines parameterization: Bull. Seism. Soc. Am., v. 81, p. 524-552.
Neri, M., Acocella, V., Behncke, B., Maiolino, V., Ursino A., and Velardita, R., 2005, Contrasting triggering mechanisms of the 2001 and 2002–2003 eruptions of Mount Etna (Italy): J. Volcanol. Geoth. Res., v. 144, p. 235– 255.
Patanè, D., Barberi, G, Cocina, O., De Gori, P., and Chiarabba, C., 2006, Time-resolved seismic tomography detects magma intrusions at Mount Etna: Science, v. 313, p. 821-823.
Patanè, D., Chiarabba, C., Cocina,O., De Gori, P., Moretti, M., and Boschi, E., 2002, Tomographic images and 3D earthquake locations of the seismic swarm preceding the 2001 Mt. Etna eruption: Evidence for a dyke intrusion: Geophys. Res. Lett., v. 29 (10), 1497, doi:10.1029/2001GL014391.
Patanè, D., Mattia, M., and Aloisi, M., 2005, Shallow intrusive processes during 2002-2004 and current volcanic activity at Mt. Etna: Geophys. Res. Lett., v. 32, L06302, doi: 10.1029/2004GL021773.
Rietbrock, A., 2001, P wave attenuation structure in the fault area of the 1995 Kobe earthquake. J. Geophys. Res., v. 106, p. 4141– 4154.
Sanders, C.O., Ponko, S.C., Nixon, L.D, and Schwartz, A., 1995, Seismological evidence for magmatic and hydrothermal structure in Long Valley Caldera from local earthquake attenuation and velocity tomography: J. Geophys. Res., v. 100, p. 8311-8326.
Scandone, R., Cashman, K.V., and Malone, S.D., 2007, Magma supply, magma ascent and the style of volcanic eruptions: Earth and Planet. Sci. Lett., v. 253, p. 513–529.