After almost 8 months of quiescence, a new sequence of low-to-mild intensity eruptions characterized the activity of Etna volcano between January and April 2017. The activity started at a vent located between the old and the new cone of the South East Crater, and was characterized by moderate Strombolian eruptions accompanied by lava flows. The weak volcanic events of 2017 constitute a breakpoint in the post-2011 eruptive behavior of Etna, which had shown the most explosive eruptions of the last two decades. All erupted rocks are K-trachybasalts with compositions similar to those of other recently erupted products. However, whole rock data reveal some chemical differences of the 2017 magmas compared to post-2011 products. Major differences have been observed with respect to products of the 2011-13 paroxysmal sequence, especially concerning some major (Fe and Ca) and trace elements (Ba, Nb, Ta). Conversely, the 2017 whole rock compositions show affinities with the 2015-16 magmas emitted at Voragine.These data, together with variations of some incompatible trace element ratios (Zr/Nb, Ba/Ta), support the idea that the 2017 products can be the result of a different evolutionary path of magmas that have fed the activity before the 2015-16 eruptions at Voragine. Magma evolution could have been driven by progressive substitution of the residing magmas by recharge with new magma. Modeling of geodetic data suggests: i) recharging phase (June 2016 - early March 2017) by fresh magma occurring at depth of ~6.3 km bsl and ii) volcano-scale deflation in late March 2017 related to depressurization of a source located at depth of ~4.6 km bsl. All these observations suggest that the deep recharging magma progressively replaced (and mixed with) the residual one from the apical region of the reservoir, therefore lending credit to a selffeeding rejuvenation mechanism of the volcano plumbing system.
Self-feeding rejuvenation of a volcano plumbing system following major explosive eruptions: evidence from the February-April 2017 eruptive activity at Etna
Viccaro M.
Membro del Collaboration Group
;Palano M.Membro del Collaboration Group
;Giuffrida M.Membro del Collaboration Group
;ZUCCARELLO, FRANCESCOMembro del Collaboration Group
;Gresta S.Membro del Collaboration Group
2018-01-01
Abstract
After almost 8 months of quiescence, a new sequence of low-to-mild intensity eruptions characterized the activity of Etna volcano between January and April 2017. The activity started at a vent located between the old and the new cone of the South East Crater, and was characterized by moderate Strombolian eruptions accompanied by lava flows. The weak volcanic events of 2017 constitute a breakpoint in the post-2011 eruptive behavior of Etna, which had shown the most explosive eruptions of the last two decades. All erupted rocks are K-trachybasalts with compositions similar to those of other recently erupted products. However, whole rock data reveal some chemical differences of the 2017 magmas compared to post-2011 products. Major differences have been observed with respect to products of the 2011-13 paroxysmal sequence, especially concerning some major (Fe and Ca) and trace elements (Ba, Nb, Ta). Conversely, the 2017 whole rock compositions show affinities with the 2015-16 magmas emitted at Voragine.These data, together with variations of some incompatible trace element ratios (Zr/Nb, Ba/Ta), support the idea that the 2017 products can be the result of a different evolutionary path of magmas that have fed the activity before the 2015-16 eruptions at Voragine. Magma evolution could have been driven by progressive substitution of the residing magmas by recharge with new magma. Modeling of geodetic data suggests: i) recharging phase (June 2016 - early March 2017) by fresh magma occurring at depth of ~6.3 km bsl and ii) volcano-scale deflation in late March 2017 related to depressurization of a source located at depth of ~4.6 km bsl. All these observations suggest that the deep recharging magma progressively replaced (and mixed with) the residual one from the apical region of the reservoir, therefore lending credit to a selffeeding rejuvenation mechanism of the volcano plumbing system.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
