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首页> 外文期刊>Journal of Volcanology and Geothermal Research2012V243-244NOCT,15 >Volcano-tectonic earthquakes: A new tool for estimating intrusive volumes and forecasting eruptions
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Volcano-tectonic earthquakes: A new tool for estimating intrusive volumes and forecasting eruptions

机译：火山构造地震：一种估算侵入量和预测喷发的新工具

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摘要

We present data on 136 high-frequency earthquakes and swarms, termed volcano-tectonic (VT) seismicity, which preceded 111 eruptions at 83 volcanoes, plus data on VT swamis that preceded intrusions at 21 other volcanoes. We find that VT seismicity is usually the earliest reported seismic precursor for eruptions at volcanoes that have been dormant for decades or more, and precedes eruptions of all magma types from basaltic to rhyolitic and all explosivities from VEI 0 to ultraplinian VEI 6 at such previously long-dormant volcanoes. Because large eruptions occur most commonly during resumption of activity at long-dormant volcanoes, VT seismicity is an important precursor for the Earth's most dangerous eruptions. VT seismicity precedes all explosive eruptions of VEI >= 5 and most if not all VEI 4 eruptions in our data set. Surprisingly we find that the VT seismicity originates at distal locations on tectonic fault structures at distances of one or two to tens of kilometers laterally from the site of the eventual eruption, and rarely if ever starts beneath the eruption site itself. The distal VT swarms generally occur at depths almost equal to the horizontal distance of the swarm from the summit out to about 15 km distance, beyond which hypocenter depths level out. We summarize several important characteristics of this distal VT seismicity including: swarm-like nature, onset days to years prior to the beginning of magmatic eruptions, peaking of activity at the time of the initial eruption whether phreatic or magmatic, and large non-double couple component to focal mechanisms. Most importantly we show that the intruded magma volume can be simply estimated from the cumulative seismic moment of the VT seismicity from:
机译：我们提供了136个高频地震和群的数据，这些地震和群被称为火山构造（VT）地震活动，先于83座火山爆发了111次喷发，另外还包含了VT震群的数据，之后又侵入了其他21座火山。我们发现，VT地震活动性通常是据报道最早休眠数十年或更长时间的火山喷发的地震前兆，并且在这种岩浆爆发之前，先发生了从玄武岩到流纹岩的所有岩浆类型的喷发，以及从VEI 0到超柱状VEI 6的所有爆炸性喷发。 -休眠火山。由于大型火山爆发通常是在长休眠火山恢复活动期间发生的，因此VT地震活动是地球上最危险的火山爆发的重要先兆。在我们数据集中所有VEI> = 5的爆发性爆发以及大多数（如果不是全部）VEI 4爆发之前，VT地震活动性都在之前。出乎意料的是，我们发现VT地震活动起源于构造断层结构的远端位置，距最终喷发地点的横向距离为一到两到几十公里，而且很少在喷发地点本身以下开始。远侧VT群的深度通常等于该群从山顶向外的水平距离，直到大约15 km，震源深度超过该水平距离。我们总结了这种远端VT地震活动的几个重要特征，包括：群状性质，岩浆喷发开始前几天到几年的发作，初次喷发时的活动达到顶峰（无论是潜伏还是岩浆），以及大型非双生夫妇焦点机制的组成部分。最重要的是，我们表明可以从VT地震活动的累积地震矩简单估算出侵入岩​​浆的体积：

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