Degassing, Crystallization and Rheology of Hawaiitic Lava Flows: the Case of the 1669 AD Eruption of Mount Etna (Italy)

Autor: Gabriele Lanzafame, Pier Paolo Giacomoni, Federico Casetta, Lucia Mancini, Gianluca Iezzi, Massimo Coltorti, Carmelo Ferlito
Rok vydání: 2022
Předmět:
Zdroj: Journal of Petrology. 63
ISSN: 1460-2415
0022-3530
DOI: 10.1093/petrology/egac115
Popis: Understanding lava flow dynamics during major effusive events is of paramount importance in volcanic areas characterized by a high risk of lava invasion. Mount Etna volcano (Sicily, Italy) has a long history of eruptions characterized by the emplacement of kilometer-wide lava fields, which have often reached the distal parts of the volcanic edifice, nowadays the location of numerous population centers. The 1669 eruption was one of the volcano’s most important events in historic times due to the low altitude of the eruptive vent and the high volume of emitted products (607 ± 105 × 106 m3), with lava flows that destroyed numerous villages located along their path. The flows reached the city of Catania, at a distance of >16 km from the emission point. In this work, we investigate the products of the 1669 eruption through geochemical, mineralogical, 2D and 3D textural analyses with the aim of reconstructing the degassing, crystallization and rheological history of the magma and lavas in pre- to post-eruptive conditions. Combining geothermobarometric and hygrometric models allowed us to estimate magmatic water content (4.1 wt.%) before the eruption, whereas the syn-eruptive crystal content (10 vol.% at the onset of flowing) was retrieved through the textural analysis of pyroclasts sampled from the near-vent fallout. Finally, crystallization and degassing occurring at surface conditions were reconstructed using the textural and mineralogical analysis of lavas. Results were integrated in a three-phase (melt + crystal + bubble) rheological model indicating that lava viscosity, at the onset of the eruption, was low enough (
Databáze: OpenAIRE
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