Hydrothermal fluid flow and deformation in large calderas: Inferences from numerical simulations
Hydrothermal fluid flow and deformation in large calderas: Inferences from numerical simulations
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DOI：
10.1029/2006jb004689
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发表时间：
2007-02-24
影响因子：
3.9
通讯作者：
Hsieh, Paul A.
中科院分区：
文献类型：
--
作者：
Hurwitz, Shaul;Christiansen, Lizet B.;Hsieh, Paul A.
[1]大型破火山口的膨胀和收缩传统上被解释为由嵌入弹性或粘弹性半空间的离散源的体积变化引起的，尽管也有人认为热液流体可能起作用。为了验证后一种假设，我们通过耦合两个数值代码(1)模拟多孔或裂隙介质中的流动的TOUGH2 [Pruess et al.， 1999]和(2)模拟线性弹性多孔介质中的流动和变形的BIOT2 [Hsieh， 1996]，对热液流体在破口中的流动和孔弹性变形进行了数值模拟。在模拟中，高温水（350摄氏度）以不同的速率注入一个圆柱体（半径50公里，高度3 - 5公里）。敏感性分析表明，渗透率及其各向异性值、热液注入深度和速率以及剪切模量的微小差异可能导致地表位移或隆升的幅度、速率和几何形状发生显著变化。一些模拟的隆升速率与观测到的大型破火山口隆升速率相似，这表明向浅层地壳注入含水流体可能解释了在破火山口观测到的一些变形。
[ 1] Inflation and deflation of large calderas is traditionally interpreted as being induced by volume change of a discrete source embedded in an elastic or viscoelastic half-space, though it has also been suggested that hydrothermal fluids may play a role. To test the latter hypothesis, we carry out numerical simulations of hydrothermal fluid flow and poroelastic deformation in calderas by coupling two numerical codes: ( 1) TOUGH2 [Pruess et al., 1999], which simulates flow in porous or fractured media, and ( 2) BIOT2 [ Hsieh, 1996], which simulates fluid flow and deformation in a linearly elastic porous medium. In the simulations, high-temperature water ( 350 degrees C) is injected at variable rates into a cylinder ( radius 50 km, height 3 - 5 km). A sensitivity analysis indicates that small differences in the values of permeability and its anisotropy, the depth and rate of hydrothermal injection, and the values of the shear modulus may lead to significant variations in the magnitude, rate, and geometry of ground surface displacement, or uplift. Some of the simulated uplift rates are similar to observed uplift rates in large calderas, suggesting that the injection of aqueous fluids into the shallow crust may explain some of the deformation observed in calderas.