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首页> 外文期刊>Journal of Volcanology and Geothermal Research >Hazards From Pyroclastic Density Currents At Mt. Etna (italy)
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Hazards From Pyroclastic Density Currents At Mt. Etna (italy)

机译：山中火山碎屑流的危害。埃特纳火山（意大利）

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Despite the recent recognition of Mount Etna as a periodically violently explosive volcano, the hazards from various types of pyroclastic density currents (PDCs) have until now received virtually no attention at this volcano. Large-scale pyroclastic flows last occurred during the caldera-forming Ellittico eruptions, 15-16 ka ago, and the risk of them occurring in the near future is negligible. However, minor PDCs can affect much of the summit area and portions of the upper flanks of the volcano. During the past -20 years, small pyroclastic flows or base-surge-like vapor and ash clouds have occurred in at least 8 cases during summit eruptions of Etna. Four different mechanisms of PDC generation have been identified during these events: (1) collapse of pyroclastic fountains (as in 2000 and possibly in 1986); (2) phreatomagmatic explosions resulting from mixing of lava with wet rock (2006); (3) phreatomagmatic explosions resulting from mixing of lava with thick snow (2007); (4) disintegration of the unstable flanks of a lava dome-like structure growing over the rim of one of the summit craters (1999). All of these recent PDCs were of a rather minor extent (maximum runout lengths were about 1.5 km in November 2006 and March 2007) and thus they represented no threat for populated areas and human property around the volcano. Yet, events of this type pose a significant threat to the lives of people visiting the summit area of Etna, and areas in a radius of 2 km from the summit craters should be off-limits anytime an event capable of producing similar PDCs occurs. The most likely source of further PDCs in the near future is the Southeast Crater, the youngest, most active and most unstable of the four summit craters of Etna, where 6 of the 8 documented recent PDCs originated. It is likely that similar hazards exist in a number of volcanic settings elsewhere, especially at snow- or glacier-covered volcanoes and on volcano slopes strongly affected by hydrothermal alteration.
机译：尽管最近已将埃特纳火山定为周期性爆发性爆炸的火山，但迄今为止，各种火山碎屑密度流（PDC）的危害实际上尚未引起该火山的注意。大规模的火山碎屑流最后一次发生在火山口形成的Ellittico喷发之前，发生时间为15-16 ka，而在不久的将来发生喷发的风险可以忽略不计。但是，较小的PDC可能会影响火山的大部分顶峰区域和部分上翼。在过去的-20年中，在埃特纳火山顶喷发期间，至少有8例发生了小的火山碎屑流或类似基波的蒸气和灰云。在这些事件中，已经确定了四种不同的PDC生成机制：（1）火山碎屑源的崩溃（如2000年和1986年）； （2）熔岩与湿岩石混合引起的岩浆爆炸（2006）； （3）熔岩与厚厚的积雪混合引起的岩浆爆炸（2007）； （4）在一个火山口之一的边缘上生长的熔岩圆顶状结构的不稳定侧面解体（1999）。最近所有这些PDC的范围都较小（2006年11月和2007年3月的最大跳动长度约为1.5 km），因此它们对火山周围的人口稠密地区和人类财产没有威胁。但是，此类事件严重威胁着前往埃特纳火山峰顶地区的人们的生命，并且只要能够产生类似PDC的事件发生，距离峰顶陨石坑2公里半径的区域均应禁止进入。在不远的将来，进一步的PDC的最可能来源是东南火山口，它是埃特纳火山的四个山顶陨石坑中最年轻，最活跃和最不稳定的地方，在最近记录的8个PDC中，有6个起源于此。在其他地方的许多火山环境中也可能存在类似的危害，特别是在积雪或冰川覆盖的火山以及受热液蚀变强烈影响的火山斜坡上。

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