Istituto Nazionale di Geofisica e Vulcanologia, Bologna, 40128, Italy.
Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan.
Nat Commun. 2018 Feb 13;9(1):654. doi: 10.1038/s41467-018-02901-0.
Explosive super-eruptions can erupt up to thousands of km of magma with extremely high mass flow rates (MFR). The plume dynamics of these super-eruptions are still poorly understood. To understand the processes operating in these plumes we used a fluid-dynamical model to simulate what happens at a range of MFR, from values generating intense Plinian columns, as did the 1991 Pinatubo eruption, to upper end-members resulting in co-ignimbrite plumes like Toba super-eruption. Here, we show that simple extrapolations of integral models for Plinian columns to those of super-eruption plumes are not valid and their dynamics diverge from current ideas of how volcanic plumes operate. The different regimes of air entrainment lead to different shaped plumes. For the upper end-members can generate local up-lifts above the main plume (over-plumes). These over-plumes can extend up to the mesosphere. Injecting volatiles into such heights would amplify their impact on Earth climate and ecosystems.
爆发性超级喷发可以喷发数千公里的岩浆，具有极高的质量流速 (MFR)。这些超级喷发的羽流动力学仍然知之甚少。为了了解这些羽流中发生的过程，我们使用流体动力学模型模拟了一系列 MFR 下的情况，从产生强烈普林尼安柱的数值（如 1991 年皮纳图博火山喷发）到导致共生熔岩层羽流的上限成员，如多巴超级喷发。在这里，我们表明，普林尼安柱的整体模型对超级喷发羽流的简单外推是无效的，它们的动力学与火山羽流如何运作的现有观念相背离。不同的空气夹带模式导致了不同形状的羽流。对于上限成员，可以在主羽流上方产生局部上升（上羽流）。这些上羽流可以延伸到中层。将挥发物注入如此高的高度将放大它们对地球气候和生态系统的影响。
