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首页> 外文期刊>Journal of Volcanology and Geothermal Research >Modelling the lava dome extruded at Soufriere Hills Volcano, Montserrat, August 2005-May 2006 Part II: Rockfall activity and talus deformation
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Modelling the lava dome extruded at Soufriere Hills Volcano, Montserrat, August 2005-May 2006 Part II: Rockfall activity and talus deformation

机译：2005年8月至2006年5月在蒙特塞拉特Soufriere Hills火山中挤出的熔岩穹顶建模第二部分：落石活动和距骨变形

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摘要

During many lava dome-forming eruptions, persistent rockfalls and the concurrent development of a substantial talus apron around the foot of the dome are important aspects of the observed activity. An improved understanding of internal dome structure, including the shape and internal boundaries of the talus apron, is critical for determining when a lava dome is poised for a major collapse and how this collapse might ensue. We consider a period of lava dome growth at the Soufriere Hills Volcano, Montserrat, from August 2005 to May 2006, during which a ～100×10~6 m~3 lava dome developed that culminated in a major dome-collapse event on 20 May 2006. We use an axi-symmetrical Finite Element Method model to simulate the growth and evolution of the lava dome, including the development of the talus apron. We first test the generic behaviour of this continuum model, which has core lava and carapace/talus components. Our model describes the generation rate of talus, including its spatial and temporal variation, as well as its post-generation deformation, which is important for an improved understanding of the internal configuration and structure of the dome. We then use our model to simulate the 2005 to 2006 Soufriere Hills dome growth using measured dome volumes and extrusion rates to drive the model and generate the evolving configuration of the dome core and carapace/talus domains. The evolution of the model is compared with the observed rockfall seismicity using event counts and seismic energy parameters, which are used here as a measure of rockfall intensity and hence a first-order proxy for volumes. The range of model-derived volume increments of talus aggraded to the talus slope per recorded rockfall event, approximately 3×10~3-13×10~3 m~3 per rockfall, is high with respect to estimates based on observed events. From this, it is inferred that some of the volumetric growth of the talus apron (perhaps up to 60-70%) might have occurred in the form of aseismic deformation of the talus, forced by an internal, laterally spreading core. Talus apron growth by this mechanism has not previously been identified, and this suggests that the core, hosting hot gas-rich lava, could have a greater lateral extent than previously considered.
机译：在许多形成熔岩穹顶的喷发过程中，持续的落石以及在穹顶脚周围同时形成大量距骨围裙的活动是观测活动的重要方面。对内部穹顶结构（包括距骨围裙的形状和内部边界）的更好理解对于确定何时熔岩穹顶准备发生重大塌陷以及如何发生塌陷至关重要。我们考虑了2005年8月至2006年5月在蒙特塞拉特Soufriere Hills火山中熔岩穹顶的生长时期，在此期间形成了〜100×10〜6 m〜3的熔岩穹顶，并在5月20日发生了一次重大的穹顶坍塌事件。 2006年。我们使用轴对称有限元方法模型来模拟熔岩穹顶的生长和演化，包括距骨围裙的发展。我们首先测试该连续体模型的一般行为，该模型具有核心熔岩和甲壳/距骨成分。我们的模型描述了距骨的发生率，包括其时空变化及其发生后的变形，这对于增进对圆顶内部结构和结构的理解非常重要。然后，我们使用模型来测量2005年至2006年Soufriere Hills穹顶的增长，使用测得的穹顶体积和挤压速率来驱动该模型，并生成穹顶核心和甲壳/距骨域的演化配置。使用事件计数和地震能量参数将模型的演化与观察到的落石地震活动性进行比较，此处将其用作落石强度的度量，因此是体积的一阶代理。对于每个观测到的落石事件，模型导出的距骨体积增量到距骨坡度的范围相对于基于观测到的事件的估计值大约为3×10〜3-13×10〜3 m〜3。由此可以推断，距骨围裙的一些体积增长（可能高达60-70％）可能是由于距骨内部的横向扩展而引起的距骨的抗震变形。距骨围裙通过这种机制的生长以前尚未被发现，这表明容纳富含热气的熔岩的岩心的横向范围可能比以前认为的要大。

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    A.J. Hale; E.S. Calder; S.C. Loughlin; G. Wadge; G.A. Ryan;

  • 作者单位

    School of Geosciences, The University of Sydney, NSW 2006, Australia;

    Centre for Geohazards, Dept. Geology, State University of New York at Buffalo, NY 14260, USA;

    British Geological Survey, Edinburgh, EH9 3LA, UK;

    Environmental Systems Science Centre, University of Reading, Reading RG6 6AI, UK;

    Institute of Earth Science and Engineering, University of Auckland, 1142, New Zealand;

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  • 正文语种 eng
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  • 关键词

    lava dome; talus; rockfall; seismicity;

    机译：熔岩穹顶距骨落石地震性;

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