Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/5109
AuthorsBonforte, A.* 
Gambino, S.* 
Neri, M.* 
TitleIntrusion of eccentric dikes: The case of the 2001 eruption and its role in the dynamics of Mt. Etna volcano
Issue DateJun-2009
Series/Report no./471 (2009)
DOI10.1016/j.tecto.2008.09.028
URIhttp://hdl.handle.net/2122/5109
Keywordsstress release
dike
volcano-tectonics
flank instability
Mt. Etna
instrumental monitoring
Subject Classification04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous 
04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes 
04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous 
04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous 
04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy 
04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous 
04. Solid Earth::04.04. Geology::04.04.09. Structural geology 
04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous 
04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology 
04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous 
04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress 
04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics 
04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous 
04. Solid Earth::04.08. Volcanology::04.08.03. Magmas 
04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring 
04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk 
05. General::05.02. Data dissemination::05.02.99. General or miscellaneous 
05. General::05.02. Data dissemination::05.02.02. Seismological data 
05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions 
AbstractThe 2001 eruption represents one of the most studied events both from volcanological and geophysical point of view on Mt. Etna. This eruption was a crucial event in the recent dynamics of the volcano, marking the passage from a period (March 1993–June 2001) of moderate stability with slow, continuous flank sliding and contemporaneous summit eruptions, to a period (July 2001 to present) of dramatically increased flank deformations and flank eruptions. We show new GPS data and high precision relocation of seismicity in order to demonstrate the role of the 2001 intrusive phase in this change of the dynamic regime of the volcano. GPS data consist of two kinematic surveys carried out on 12 July, a few hours before the beginning of the seismic swarm, and on 17 July, just after the onset of eruptive activity. A picture of the spatial distribution of the sin-eruptive seismicity has been obtained using the HypoDD relocation algorithm based on the double-difference (DD) technique. Modeling of GPS measurements reveals a southward motion of the upper southern part of the volcano, driven by a NNW–SSE structure showing mainly left-lateral kinematics. Precise hypocenter location evidences an aseismic zone at about sea level, where the magma upraise was characterized by a much higher velocity and an abrupt westward shift, revealing the existence of a weakened or ductile zone. These results reveal how an intrusion of a dike can severely modify the shallow stress field, triggering significant flank failure. In 2001, the intrusion was driven by a weakened surface, which might correspond to a decollement plane of the portion of the volcano affected by flank instability, inducing an additional stress testified by GPS measurements and seismic data, which led to an acceleration of the sliding flanks.
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