Science Behind the Devastating Mount Etna Eruption

Abstract
An understanding of destructive historic eruptions has important implications for the assessment of active plumbing systems and the processes that might precede future hazardous eruptions. At Mount Etna (Sicily, Italy), magma production and eruption frequency have increased dramatically since 1970, however, the recent eruptions are considerably less voluminous than those of the 17th century, which occurred at greater intervals. Seventeenth century activity culminated in the 1669 flank eruption, the most voluminous and destructive in Etna’s recorded history, marking the beginning of a new eruptive period. In this study, we examine trace element zoning patterns recorded in clinopyroxene (lava hosted microcrysts: 0·5–1 mm, lava hosted macrocrysts: 1–5 mm and scoria hosted megacrysts: >5 mm) to reconstruct magma dynamics leading up to the 1669 eruption. The clinopyroxene data are considered alongside previous studies of olivine and plagioclase to present an updated conceptual model for the plumbing system, providing a better understanding of magmatic processes in the lead up to hazardous volcanism. Petrological observations in combination with laser ablation ICP-MS mapping reveal sharp compositional zoning of clinopyroxene, not seen in major element transects. Trace element data, including Cr, Zr, Ni and rare earth elements, show that core, mantle and rim regions originated in distinct magmatic environments. Chromium-rich cores (up to 1080 ppm Cr) are in disequilibrium with the glassy-microcrystalline host groundmass and indicate crystal inheritance from a primitive magma source.