The andesitic Tongariro Volcanic Complex in the Central North Island of New Zealand comprises tens of vents along an actively extending graben. Past work has hypothesised that multiple vents may operate during a single explosive eruption episode, providing an unprecedented hazard challenge for this region. The stratigraphic record suggests an irregular clustering of eruption episodes over time, including an unusual ≤ 200-year-long period from ~11.3–11.1 ka when several large explosive eruptions occurred. We carried out new field mapping, stratigraphy, and sedimentology of the resulting pyroclastic deposits to identify seven episodes during this period, locating the vent sites and calculating their climactic dynamic properties. Five of the episodes involved two or more vent locations that produced separate sub-Plinian/Plinian eruption columns. Eruption columns ranged between 16 and 24 km high and erupted volumes of 0.05 to 0.76 km 3 , indicating magnitudes of 4 to 5. Each of these episodes show north-to-south “unzipping” of the Tongariro Graben, with episodes beginning in northerly vents, before being joined by vents south of these. This included two scenarios; northern edifice vents followed by central edifice ones or central edifice vents followed by southern ones. In both cases, the northerly vents generally display the greatest peak eruption magnitudes and the steadiest eruptions. By contrast, the southernmost vents formed along a fault-controlled fissure-like system. These produced unsteady plumes and pyroclastic density currents. The northward widening tectonic graben structure thus influences the pattern and style of these Plinian-style eruptions. This study highlights a real possibility for an extreme hazard scenario involving successive large-scale eruptions at volcanic systems in slowly rifting environments and sheds new light on the volcano-tectonic interaction in such settings.

中文翻译：

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了解 Mt. 的多喷口 Plinian 喷发 新西兰汤加里罗火山群

新西兰北岛中部的安山岩汤加里罗火山群包括数十个沿积极延伸的地堑的喷口。过去的工作假设在一次爆发性喷发期间多个喷口可能会运行，为该地区提供了前所未有的危险挑战。地层记录表明，随着时间的推移，喷发事件不规则地聚集在一起，包括一次不寻常的≤ 200 年时间，从~11.3-11.1 ka 发生了几次大型爆炸性喷发。我们对由此产生的火山碎屑沉积物进行了新的实地测绘、地层学和沉积学，以确定这一时期的七个事件，定位喷口位置并计算其气候动态特性。其中五个事件涉及两个或多个喷口位置，这些喷口位置产生了单独的亚普林尼亚/普林尼亚喷发柱。喷发柱高 16 至 24 公里，喷发体积 0.05 至 0.76 公里 3 ，表明震级为 4 至 5 级。每一集都显示汤加里罗地堑从北向南“拉开”，从北风口开始，在被这些以南的通风口加入之前。这包括两种情况；北部大厦通风口其次是中央大厦通风口或中央大厦通风口其次是南部大厦通风口。在这两种情况下，偏北的喷口通常显示出最大的喷发峰值和最稳定的喷发。相比之下，最南端的喷口沿着断层控制的裂隙状系统形成。这些产生了不稳定的羽流和火山碎屑密度流。因此，向北扩大的构造地堑结构影响了这些普林尼式喷发的模式和风格。