Probabilistic Volcanic Hazard Assessment for Pyroclastic Density Currents From Pumice Cone Eruptions at Aluto Volcano, Ethiopia
Probabilistic Volcanic Hazard Assessment for Pyroclastic Density Currents From Pumice Cone Eruptions at Aluto Volcano, Ethiopia
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DOI：
10.3389/feart.2020.00348
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发表时间：
2020-08-31
影响因子：
2.9
通讯作者：
Yirgu, Gezahegn
中科院分区：
文献类型：
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作者：
Clarke, Ben;Tierz, Pablo;Yirgu, Gezahegn
位于埃塞俄比亚主要裂谷中的Aluto火山是一个过碱性的破火山口系统，由流纹岩(黑岩)熔岩和神秘的浮石锥组成。Aluto最近的研究发现，浮石锥喷发是高度不稳定的，并形成对流喷发羽流，这些羽流经常坍塌产生火山碎屑密度流(PDC)。我们开发了一种方法，并给出了浮岩锥火山第一次概率火山危险性评估(PVHA)的结果。通过这样做，我们估计了Aluto火山周围的PDC淹没的条件概率，并考虑了PDC灾害的不确定性。我们采用蒙特卡罗能量锥模拟方法，该方法得益于由现场调查和火山羽流模拟所提供的参数化。我们发现，尽管可能发生的喷发相对较少，但过去喷口位置的广泛分布(因此未来喷口可能在哪里打开的高度不确定性)导致大片地区可能面临被PDC淹没的风险。然而，通风口开启的不确定性意味着条件概率较低(
Aluto volcano, in the Main Ethiopian Rift, is a peralkaline caldera system, which comprises conglomerations of rhyolite (obsidian) lavas and enigmatic pumice cones. Recent work at Aluto has found that pumice cone eruptions are highly unsteady, and form convective eruption plumes that frequently collapse to generate pyroclastic density currents (PDCs). We develop a methodology and present results for the first probabilistic volcanic hazard assessment (PVHA) for PDCs at a pumice cone volcano. By doing so, we estimate the conditional probability of inundation by PDCs around Aluto volcano, incorporating the aleatory uncertainty in PDC hazard. We employ a Monte Carlo energy cone modeling approach, which benefits from parameterization informed by field investigations and volcanic plume modeling. We find that despite the relatively modest eruptions that are likely to occur, the wide distribution of past vent locations (and thus the high uncertainty of where future vents might open), results in a broad area being potentially at risk of inundation by PDCs. However, the aleatory uncertainty in vent opening means that the conditional probabilities are lower (