Bulletin of Volcanology

, Volume 73, Issue 9, pp 1311–1322

Magnetic features of the magmatic intrusion that occurred in the 2007 eruption at Stromboli Island (Italy)

  • Rosalba Napoli
  • Gilda Currenti
  • Ciro Del Negro
  • Agnese Di Stefano
  • Filippo Greco
  • Enzo Boschi
Research Article

DOI: 10.1007/s00445-011-0473-0

Cite this article as:
Napoli, R., Currenti, G., Del Negro, C. et al. Bull Volcanol (2011) 73: 1311. doi:10.1007/s00445-011-0473-0

Abstract

Significant changes in the local magnetic field marked the resumption of eruptive activity at Stromboli volcano on February 27, 2007. After differential magnetic fields were obtained by filtering out external noise using adaptive filters and seasonal thermal noise using temperature data, we identified step-like changes of 1–4 nT coincident with the opening of eruptive fissures in the upper part of the Sciara del Fuoco. The magnetic variations detected at two stations are closely related to the propagation of a shallow NE–SW magmatic intrusion extending beyond the summit craters area. These observations are consistent with those calculated using piezomagnetic models in which 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 can be related to a time-dependent relaxation process. A Maxwell rheology was assumed and the temporal evolution of the piezomagnetic field was evaluated. This allowed us to estimate the rheological properties of the medium; in particular, an average viscosity ranging between 1016 and 1017 Pa⋅s was a relaxation time τ of about 38 days.

Keywords

Stromboli Island Magnetic monitoring Piezomagnetic field Stress field Strombolian eruption 

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Rosalba Napoli
    • 1
  • Gilda Currenti
    • 1
  • Ciro Del Negro
    • 1
  • Agnese Di Stefano
    • 1
    • 2
  • Filippo Greco
    • 1
  • Enzo Boschi
    • 1
  1. 1.Istituto Nazionale di Geofisica e VulcanologiaSezione di CataniaCataniaItaly
  2. 2.Dipartimento di Ingegneria Elettrica, Elettronica e dei SistemiUniversità di CataniaCataniaItaly

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