Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/6777
AuthorsDe Martino, S.* 
Palo, M.* 
Cimini, G. B.* 
TitleA statistical study of the Stromboli volcano explosion-quakes before and during 2002-2003 eruptive crisis
Issue Date2010
URIhttp://hdl.handle.net/2122/6777
KeywordsStromboli
explosion-quakes
2002-2003 eruptive crisis
Subject Classification04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology 
AbstractWe study the seismic wavefield and the statistical properties of the Stromboli volcano explosions preceding and during 2002-2003 crisis. We analyze the recordings of a three-component seismometer operating since 23/05/2002 to 30/01/2003, including the first 34 days of the crisis. Before the crisis, we recognize three bell-shaped classes of spectra with maxima falling in the range 1–5 Hz. Spectral content has two main changes, the most prominent one occurring at the crisis onset when the frequency peak at ∼0:3 Hz increases in amplitude. Independent Component Analysis extracts three timestable independent oscillations peaked at 1.1, 1.8, and 2.5 Hz, respectively, with radial and shallow polarization indicating a stable source mechanism. Energy of the explosions is log-normally distributed, except during a twomonth time interval before the crisis when it shows also a higher mean value. The inter-occurrence time distributions display an homogeneous poissonian behaviour with a mean inter-time of 250 s, without changes at the crisis onset. Only swarms of explosions are not ruled by a Poisson process and display higher occurrence rates and higher energies. Finally, we depict a scheme of the crisis. A modification of the equilibrium is induced by rising magma that produces a change in the boundary conditions of the plumbing system. The escape from the equilibrium produces, at first, variations in the usual statistics of the explosions, then it leads to the lava effusion and to a pressure drop in the plumbing systems that induces a deep gas slug nucleation and the excitation of low frequencies.
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