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Authors: Bonforte, A.*
Gambino, S.*
Neri, M.*
Title: Intrusion of eccentric dikes: The case of the 2001 eruption and its role in the dynamics of Mt. Etna volcano
Title of journal: Tectonophysics
Series/Report no.: /471 (2009)
Publisher: Elsevier
Issue Date: Jun-2009
DOI: 10.1016/j.tecto.2008.09.028
Keywords: stress release
flank instability
Mt. Etna
instrumental monitoring
Abstract: The 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.
Appears in Collections:Papers Published / Papers in press
04.01.99. General or miscellaneous
04.01.02. Geological and geophysical evidences of deep processes
04.02.99. General or miscellaneous
04.03.99. General or miscellaneous
04.03.07. Satellite geodesy
04.04.99. General or miscellaneous
04.04.09. Structural geology
04.06.99. General or miscellaneous
04.06.08. Volcano seismology
04.07.99. General or miscellaneous
04.07.05. Stress
04.07.07. Tectonics
04.08.99. General or miscellaneous
04.08.03. Magmas
04.08.06. Volcano monitoring
04.08.08. Volcanic risk
05.02.99. General or miscellaneous
05.02.02. Seismological data
05.02.03. Volcanic eruptions

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