Tracking dynamics of magma migration in open-conduit systems

Year: 2016

Authors: Valade S., Lacanna G., Coppola D., Laiolo M., Pistolesi M., Delle Donne D., Genco R., Marchetti E., Ulivieri G., Allocca C., Cigolini C., Nishimura T., Poggi P., Ripepe M.

Autors Affiliation: ‎Univ Florence, Dipartimento Sci Terra, Florence, Italy;‎ Univ Turin, Dipartimento Sci Terra, Turin, Italy;‎ Univ Palermo, Dipartimento Sci Terra & Mare, Palermo, Italy;‎ Tohoku Univ, Dept Geophys, Sendai, Miyagi, Japan; Ist Nazl Ottica, CNR, Florence, Italy

Abstract: Open-conduit volcanic systems are typically characterized by unsealed volcanic conduits feeding permanent or quasi-permanent volcanic activity. This persistent activity limits our ability to read changes in the monitored parameters, making the assessment of possible eruptive crises more difficult. We show how an integrated approach to monitoring can solve this problem, opening a new way to data interpretation. The increasing rate of explosive transients, tremor amplitude, thermal emissions of ejected tephra, and rise of the very-long-period (VLP) seismic source towards the surface are interpreted as indicating an upward migration of the magma column in response to an increased magma input rate. During the 2014 flank eruption of Stromboli, this magma input preceded the effusive eruption by several months. When the new lateral effusive vent opened on the Sciara del Fuoco slope, the effusion was accompanied by a large ground deflation, a deepening of the VLP seismic source, and the cessation of summit explosive activity. Such observations suggest the drainage of a superficial magma reservoir confined between the crater terrace and the effusive vent. We show how this model successfully reproduces the measured rate of effusion, the observed rate of ground deflation, and the deepening of the VLP seismic source. This study also demonstrates the ability of the geophysical network to detect superficial magma recharge within an open-conduit system and to track magma drainage during the effusive crisis, with a great impact on hazard assessment.

Journal/Review: BULLETIN OF VOLCANOLOGY

Volume: 78 (11)      Pages from: 78-1  to: 78-12

More Information: We wish to thank Salvatore Zaia and Vivian Anceschi for their continuous support at the Centro Operativo Avanzato of Stromboli (COA). This work was supported by the Italian Civil Protection in the framework of the DEVNET project. The paper has been improved by constructive comments by the Associate Editor Matthew Patrick, the reviewer Matt Haney, and an anonymous reviewer, all of whom we wish to thank.
KeyWords: Effusive eruption; Stromboli volcano; Conduit processes; Geophysical monitoring
DOI: 10.1007/s00445-016-1072-x

Citations: 46
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