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首页> 外文学位 >A seismological comparison of Bezymianny Volcano, Russia, and Mount St. Helens Volcano, Washington.
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A seismological comparison of Bezymianny Volcano, Russia, and Mount St. Helens Volcano, Washington.

机译：俄罗斯Bezymianny火山和华盛顿圣海伦火山的地震比较。

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摘要

Bezymianny Volcano, Russia and Mount St. Helens, Washington are examples of eruptions involving the sector collapse of a volcano. The study and comparison of Mount St. Helens and Bezymianny has led to a better understanding of the precursory seismicity prior to eruptions. The shallow moment release prior to an eruption is dependent on the time since the last eruption at both volcanoes. This relationship is independent of the type of eruption that ensues, suggesting that overcoming the strength of the plug in shallow conduit must occur prior to the initiation of an eruption. This finding has obvious implications for forecasting eruptions, and more importantly, for forecasting failed eruptions.;The comparison of multiplets at Bezymianny and Mount St. Helens suggests that the physical properties of magma in the shallow conduit controlled the occurrence and behavior of multiplets. When there is shallow crystallization and active degassing of the plug within the conduit, multiplets are abundant. Alternatively, when there is no shallow crystallization in a semi-open system, as at Bezymianny, multiplets were less abundant. At both volcanoes prior to an explosion, the multiplet percentage of total seismicity drops, and the average amplitude of each multiplet increases. Multiplet characteristics such as the multiplet percentage of total seismicity, multiplet durations, and the number of contemporaneous multiplets can be tracked prior to an eruption to forecast the type of eruption that will ensue.;The future volcanic activity at Mount St. Helens will likely diverge from the current explosive activity at Bezymianny. Without any additional input of mafic material or additional gas content, intermittent viscous dome building at Mount St. Helens will likely continue. In general, the high gas content of the magmas at Bezymianny compared to Mount St. Helens has driven more explosivity during eruptions despite the lower silica content and resultant lower viscosity magma at Bezymianny compared to Mount St. Helens. In future eruptions at Bezymianny and Mount St. Helens, the seismic energy release prior to eruptions will be dictated by the time since the last eruption. Stronger seismicity can be expected in cases where the conduit bends around existing dome.
机译：俄罗斯的Bezymianny火山和华盛顿的圣海伦火山就是涉及火山扇形坍塌的喷发例子。对圣海伦斯山和Bezymianny山的研究和比较使人们对喷发前的地震活动有了更好的了解。喷发之前的浅矩释放取决于自两个火山最后一次喷发以来的时间。这种关系与随后发生的喷发类型无关，表明必须在喷发开始之前克服浅管道中的塞子强度。这一发现对预报火山爆发具有更明显的意义，更重要的是，对失败的火山爆发也具有重要的预测意义。当管道中的塞子出现浅结晶和主动除气时，多重峰就丰富了。或者，当在半开放系统中没有浅结晶时，例如在Bezymianny，多重峰较少。在爆炸前的两个火山中，总地震活动度的多重性百分比下降，每个多重性的平均振幅增加。可以在喷发之前跟踪多重特征，例如总地震活动的多重百分比，多重持续时间和同期多重数目，以预测将要发生的喷发类型；未来圣海伦斯火山的火山活动可能会发散来自Bezymianny目前的爆炸活动。如果没有任何额外的镁铁质材料或气体含量的输入，圣海伦斯山的间歇性粘性圆顶建筑将很可能继续。通常，与圣海伦火山相比，Bezymianny岩浆的高瓦斯含量推动了火山爆发期间的爆炸，尽管Bezymianny岩浆中的二氧化硅含量较低，导致岩浆的粘度较低。在未来的Bezymianny和圣海伦斯火山爆发中，爆发前的地震能量释放将取决于自上次爆发以来的时间。在导管围绕现有圆顶弯曲的情况下，可以预期会产生更大的地震作用。

著录项

  • 作者

    Thelen, Weston Albert.;

  • 作者单位

    University of Washington.;

  • 授予单位 University of Washington.;
  • 学科 Geology.;Geophysics.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 226 p.
  • 总页数 226
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;地球物理学;
  • 关键词

  • 入库时间 2022-08-17 11:38:29

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