Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/6375
AuthorsNapoli, R.* 
Currenti, G.* 
Del Negro, C..* 
Di Stefano, A.* 
Greco, F.* 
Boschi, E.* 
TitleMagnetic features of the magmatic intrusion occurred in 2007 eruption at Stromboli Island (Italy.)
Issue Date2010
URIhttp://hdl.handle.net/2122/6375
KeywordsStromboli Island
magnetic monitoring
piezomagnetic field
stress field
Subject Classification04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring 
AbstractSignificant changes in the local magnetic field marked the resumption of the eruptive activity at Stromboli volcano on February 27, 2007. After differential magnetic fields were filtered from the external noise by adaptive filters and from the seasonal thermic noise using temperature data, we highlighted step-like changes of 1-4 nT coincident with the eruptive fissures opening in the upper part of the Sciara del Fuoco. The magnetic variations detected at 2 stations are closely related to the propagation of a shallow NE-SW magmatic intrusion outside the summit craters area . These observations are consistent with those calculated from piezomagnetic models, where stress-induced changes in rock magnetization are produced by the magmatic intrusion. No significant magnetic changes were observed when the first fractures opened along the NE crater rim. Indeed, the stress-induced magnetization caused by this magmatic activity is expected to be too low because of the structural weakness and/or thermal state of the summit area. The continuous long-term decay characterizing the post-eruptive magnetic pattern was related to a time-dependent relaxation process. A Maxwell rheology was assumed and the temporal evolution of the piezomagnetic field was evaluated. This allowed for the estimate of the rheological properties of the medium, in particular an average viscosity ranging between 1016 and 1017 Pas was achieved involving a relaxation time τ of about 38 days.
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