Viccaro Marco, Giuffrida Marisa, Zuccarello Francesco, Scandura Mariabenedetta, Palano Mimmo, Gresta Stefano
Università di Catania, Dipartimento di Scienze Biologiche, Geologiche e Ambientali - Sezione di Scienze della Terra, Corso Italia 57, I-95129, Catania, Italy.
Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania - Osservatorio Etneo, Piazza Roma 2, 95125, Catania, Italy.
Sci Rep. 2019 Apr 30;9(1):6717. doi: 10.1038/s41598-019-43211-9.
A new sequence of eruptions occurred at Mt. Etna volcano during the first half of 2017, after almost 8 months of quiescence. These episodes had low-to-mild intensity and markedly differ from the violent paroxysms occurred at the Voragine Crater (VOR) during December 2015 and May 2016. Despite the general weak explosive nature of the eruptions, the activity during 2017 revealed unusually complex dynamics of magma ascent and interaction. Detection and investigation of such dynamics required a multidisciplinary approach in which bulk rock compositions, crystal chemical zoning, diffusion chronometry and ground deformation data have been combined. Bulk rock major and trace elements suggest that the 2017 magmas followed a differentiation path similar to that experienced by magmas erupted at Mt. Etna during the 2015-16 eruptions at VOR. Olivine core compositions and zoning patterns indicate the presence of multiple magmatic environments at depth that strictly interacted each other through some episodes of intrusion and mixing before and during the 2017 eruptive events. Timescales retrieved from diffusion chronometry on olivine normal and reverse zoning correlate well with the ground deformation stages detected through geodetic data and associated models, thus allowing to track the evolution through time of the 2017 volcanic activity. Combination of all petrological and geodetic observations supports the idea that dynamics of magma transfer driving the eruptive episodes of 2017 have been a direct consequence of the violent eruptions occurred at VOR on May 2016, which boosted the ascent of new magma from depth and improved the efficiency of the plumbing system to transfer it upward to the surface. We propose a mechanism of self-feeding replenishment of the volcano plumbing system during 2017, where magma recharge from depth is triggered by sudden unloading of the magma column consequential to the violent paroxysmal activity occurred on May 2016 at VOR.
在经历了近8个月的静止期后，2017年上半年埃特纳火山发生了新一轮喷发。这些喷发活动强度较低至中等，与2015年12月和2016年5月在沃拉吉内火山口（VOR）发生的剧烈阵发性喷发明显不同。尽管这些喷发总体上具有较弱的爆炸性，但2017年的火山活动显示出岩浆上升和相互作用异常复杂的动力学特征。对这种动力学的探测和研究需要采用多学科方法，将块状岩石成分、晶体化学分带、扩散年代测定法和地面变形数据结合起来。块状岩石的主量和微量元素表明，2017年的岩浆遵循了一条与2015 - 2016年VOR火山口喷发的岩浆相似的分异路径。橄榄石核心成分和分带模式表明，深部存在多个岩浆环境，它们在2017年喷发事件之前和期间通过一些侵入和混合事件相互严格作用。从橄榄石正、反向分带的扩散年代测定法中获取的时间尺度与通过大地测量数据及相关模型检测到的地面变形阶段密切相关，从而能够追踪2017年火山活动随时间的演变。所有岩石学和大地测量观测结果的结合支持了这样一种观点，即驱动2017年喷发事件的岩浆传输动力学是2016年5月VOR火山口发生的剧烈喷发的直接结果，那次喷发促使新的岩浆从深部上升，并提高了管道系统将其向上传输至地表的效率。我们提出了一种2017年期间火山管道系统的自供料补给机制，即2016年5月VOR火山口发生的剧烈阵发性活动导致岩浆柱突然卸载，从而引发深部岩浆补给。
