Abstract Mt. Tongariro is a multi-vent volcanic complex in the central North Island of New Zealand, constructed along the axis of an active graben. Its five largest-known explosive eruption episodes occurred 11,000 years ago during a ~200 year-long paroxysm. During these, stable Plinian and collapsing sub-Plinian columns erupted from multiple sequential and synchronous vents along the graben axis. We examined the spatially varying eruption dynamics during the 200-year paroxysm through the lens of pyroclastic textures. Each eruption episode produced micro-vesicular basaltic-andesitic juvenile lapilli with high vesicle number densities and high groundmass crystallinity. Textural characteristics indicate that pressurisation via second boiling drove eruptions and rhyolite-like melt viscosities promoted brittle failure. Highly variable and mingled textures within individual juvenile lapilli evidence diverse conditions developed across the conduit during the eruption. Foamy magma rose rapidly through the conduit core, driving explosive vigour, and dragged and sheared gas-poor crystallised magma from the conduit margins. Consistent with the northward-widening graben, the most stable Plinian eruptions occurred at northern vents, under highest extensional stresses and possibly widest most stable conduits. By contrast, collapsing, unstable eruption columns occurred at southern vents, where mainly degassed and crystalline magma erupted at lower ejection rates through narrower, unstable and shifting conduits. These data collectively show how spatial variations in structure and tectonics may strongly influence explosive eruption style.

中文翻译：

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微孔火山碎屑反映了 Mt. 的多喷口玄武质安山岩 Plinian 喷发。新西兰汤加里罗

摘要山 汤加里罗是新西兰北岛中部的一个多喷口火山群，沿着活动地堑的轴线建造。其五次最大的已知爆炸性喷发事件发生在 11,000 年前，在大约 200 年的爆发期间。在此期间，沿地堑轴的多个连续和同步的喷口喷发了稳定的 Plinian 柱和塌陷的亚 Plinian 柱。我们通过火山碎屑纹理的镜头检查了 200 年爆发期间空间变化的喷发动态。每次喷发都会产生具有高泡数密度和高基质结晶度的微泡玄武岩-安山岩幼体。质地特征表明，通过二次沸腾加压推动了喷发，流纹岩状熔体粘度促进了脆性破坏。个体幼鱼唇内高度可变和混合的纹理证明在喷发期间跨越管道形成了不同的条件。泡沫岩浆通过导管核心迅速上升，驱动爆炸性的活力，并从导管边缘拖拽和剪切贫气结晶岩浆。与向北扩大的地堑一致，最稳定的普林尼火山喷发发生在北部喷口，在最高的拉伸应力和可能最宽的最稳定的管道下。相比之下，坍塌、不稳定的喷发柱发生在南部的喷口，主要是脱气和结晶的岩浆通过更窄、不稳定和移动的管道以较低的喷射率喷发。这些数据共同显示了结构和构造的空间变化可能如何强烈影响爆发式喷发方式。 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .