How Accurately Can We Model Magma Reservoir Failure With Uncertainties in Host Rock Rheology?
How Accurately Can We Model Magma Reservoir Failure With Uncertainties in Host Rock Rheology?
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在宿主岩石流变学不确定的情况下，我们如何准确地模拟岩浆储层失效？
DOI：
10.1029/2019jb018178
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Gregg, P. M.
中科院分区：
文献类型：
--
作者：
Zhan, Y.;Gregg, P. M.
预测封闭系统中火山爆发的开始需要了解其应力状态和故障可能性，这可以通过数值模拟进行研究。然而，缺乏对模型参数的约束，特别是流变学，可能会大大损害故障预测的准确性。因此，必须了解岩石性质的大的变化和不确定性是否会妨碍模型预测储层破坏的能力。一系列的二维，轴对称模型被用来研究脆性破坏启动的敏感性假设岩石属性。数值实验表明，当加压时间超过围岩的粘弹性松弛时间时，弹性模型模拟的变形和破坏起始超压值将远低于粘弹性模型。泊松比和内摩擦角对失效预测的影响比杨氏模量小得多。当杨氏模量< 40 GPa时，杨氏模量的变化显著影响失效开始前表面变形的预测。由于岩墙扩展之前的库仑破坏发育良好，较长时间的火山-构造事件可能发生在软弱的寄主岩石（E< 40 GPa）中。因此，结合地表变形与地震活动，可以提高在这些情况下的喷发预测的准确性。与大型和扁长岩浆系统相比，小型和扁长系统在故障启动之前产生的地表隆起要小得多，这表明需要更频繁的测量。
Forecasting the onset of a volcanic eruption from a closed system requires understanding its stress state and failure potential, which can be investigated through numerical modeling. However, the lack of constraints on model parameters, especially rheology, may substantially impair the accuracy of failure forecasts. Therefore, it is essential to know whether large variations and uncertainties in rock properties will preclude the ability of models to predict reservoir failure. A series of two‐dimensional, axisymmetric models are used to investigate sensitivities of brittle failure initiation to assumed rock properties. The numerical experiments indicate that the deformation and overpressure at failure onset simulated by elastic models will be much lower than the viscoelastic models, when the timescale of pressurization exceeds the viscoelastic relaxation time of the host rock. Poisson's ratio and internal friction angle have much less effect on failure forecasts than Young's modulus. Variations in Young's modulus significantly affect the prediction of surface deformation before failure onset when Young's modulus is < 40 GPa. Longer precursory volcano‐tectonic events may occur in weak host rock (E< 40 GPa) due to well‐developed Coulomb failure prior to dike propagation. Thus, combining surface deformation with seismicity may enhance the accuracy of eruption forecast in these situations. Compared to large and oblate magma systems, small and prolate systems create far less surface uplift prior to failure initiation, suggesting that more frequent measurements are necessary.
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DOI：
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发表时间：
2017
期刊：
影响因子：
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作者：
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作者：
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