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首页> 外文期刊>Journal of Volcanology and Geothermal Research >A Long-term Volcanic Hazard Event Tree For Teide-pico Viejo Stratovolcanoes (tenerife, Canary Islands)
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A Long-term Volcanic Hazard Event Tree For Teide-pico Viejo Stratovolcanoes (tenerife, Canary Islands)

机译：Teide-pico Viejo Stratovolcanoes（加那利群岛的特内里费岛）的长期火山危害事件树

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摘要

We propose a long-term volcanic hazards event tree for Teide-Pico Viejo stratovolcanoes, two complex alkaline composite volcanoes that have erupted 1.8-3 km~3 of mafic and felsic magmas from different vent sites during the last 35 ka. This is the maximum period that can be investigated from surface geology and also represents an upper time limit for the appearance of the first phonolites on that volcano. The whole process of the event tree construction was divided into three stages. The first stage included the determination of the spatial probability of vent opening for basaltic and phonolitic eruptions, based on the available geological and geophysical data. The second, involved the analysis of the different eruption types that have characterised the volcanic activity from Teide during this period. The third stage focussed on the generation of the event tree from the information obtained in the two previous steps and from the application of a probabilistic analysis on the occurrence of each possible eruption type. As for other volcanoes, the structure of the Teide-Pico Viejo Event Tree was subdivided into several steps of eruptive progression from general to more specific events. The precursory phase was assumed as an unrest episode of any geologic origin (magmatic, hydrothermal or tectonic), which could be responsible for a clear increase of volcanic activity revealed by geophysical and geochemical monitoring. According to the present characteristics of Teide-Pico Viejo and their past history, we started by considering whether the unrest episode would lead to a sector collapse or not. If the sector collapse does not occur but an eruption is expected, this could be either from the central vents or from any of the volcanoes' flanks. In any of these cases, there are several possibilities according to what has been observed in the period considered in our study. In the case that a sector collapse occurs and is followed by an eruption we considered it as a flank eruption. We conducted an experts elicitation judgement to assign probabilities to the different possibilities indicated in the event tree. We assumed long term estimations based on existing geological and historical data for the last 35 Ka, which gave us a minimum estimate as the geological record for such a long period is incomplete. However, to estimate probabilities for a short term forecast, for example during an unrest episode, we would need to include in the event tree additional information from the monitoring networks, as any possible precursors that may be identified could tell us in which direction the system will evolve. Therefore, we propose to develop future versions of the event tree to include also the precursors that might be expected on each path during the initial stages of a new eruptive event.
机译：我们为Teide-Pico Viejo平流层火山提出了一个长期的火山灾害事件树，这是两个复杂的碱性复合火山，在最后的35 ka期间，它们从不同的出风口喷出了1.8-3 km〜3的铁质和长质岩浆。这是可以从地表地质调查的最长时间，并且也代表该火山上第一种音石出现的上限时间。事件树构建的整个过程分为三个阶段。第一阶段包括根据现有的地质和地球物理数据，确定玄武岩和火山岩喷口的通风口空间概率。第二，涉及分析不同的喷发类型，这些喷发类型表征了这段时期泰德峰的火山活动。第三阶段的重点是从前两个步骤中获得的信息以及对每种可能爆发类型的发生概率分析的应用来生成事件树。至于其他火山，泰德峰-皮科维耶霍事件树的结构又细分为从一般事件到更具体事件的几个爆发过程。前期阶段被认为是任何地质起源（岩浆，热液或构造）的动荡时期，这可能是地球物理和地球化学监测揭示的火山活动明显增加的原因。根据Teide-Pico Viejo的当前特征及其过去的历史，我们首先考虑动乱事件是否会导致部门崩溃。如果没有发生扇形塌陷，但预计会发生喷发，则可能是中央喷口或任何火山侧面引起的。在任何一种情况下，根据我们研究期间所观察到的情况，都有几种可能性。在出现扇区崩溃并随后发生喷发的情况下，我们将其视为侧面喷发。我们进行了专家启发判断，将概率分配给事件树中指示的不同可能性。我们基于最近35 Ka的现有地质和历史数据进行了长期估算，这为我们提供了最低限度的估算，因为如此长时间的地质记录是不完整的。但是，要估计短期预测的概率，例如在动乱期间，我们需要在事件树中包含来自监控网络的其他信息，因为可以识别出的任何可能的前兆都可以告诉我们系统的方向会进化。因此，我们建议开发事件树的未来版本，以也包括在新爆发事件的初始阶段在每个路径上可能预期的前兆。

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