Understanding the stress distribution around shallow magma chambers is vital for forecasting eruption sites and magma propagation directions. To achieve accurate forecasts, comprehensive insight into the stress field surrounding magma chambers and near the surface is essential. Existing stress models for pressurized magma chambers often assume a homogenous elastic half-space or a heterogeneous crust with varying mechanical properties in horizontal layers. However, as many volcanoes have complex, non-horizontal, and heterogeneous layers, we enhance these assumptions by considering mechanically stratified layers with varying dips. We employed the Finite Element Method (FEM) to create numerical models simulating three chamber geometries: circular, sill-like and prolate. The primary condition was a 10 MPa excess pressure within the magma chamber, generating the stress field. Layers dips by 20-degree increments, with differing elastic moduli, represented by stiffness ratios of the successive layers (E_U/E_L) ranging from 0.01 to 100. Our findings validate prior research on heterogeneous crustal modeling, showing that high stiffness ratios disrupt stress within layers and induce local stress rotations at mismatched interfaces. Layer dip further influences stress fields, shifting the location of maximum stress concentration over varying distances. This study underscores the significance of accurately understanding mechanical properties, layer dip in volcanoes, and magma chamber geometry. Improving forecasting of future eruption vents in active volcanoes, particularly in the Andes with its deformed, folded, and non-horizontal stratified crust, hinges on this knowledge. By expanding stress models to incorporate complex geological structures, we enhance our ability to forecast eruption sites and magma propagation paths.

中文翻译：

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机械分层和层浸改变岩浆室加压引起的应力

了解浅层岩浆房周围的应力分布对于预测喷发地点和岩浆传播方向至关重要。为了实现准确的预测，全面了解岩浆房周围和地表附近的应力场至关重要。加压岩浆室的现有应力模型通常假设均匀的弹性半空间或水平层中具有不同机械特性的异质地壳。然而，由于许多火山具有复杂的、非水平的和异质的层，我们通过考虑具有不同倾角的机械分层层来增强这些假设。我们采用有限元法 (FEM) 创建数值模型来模拟三种腔室几何形状：圆形、窗台状和长方形。主要条件是岩浆室内有 10 MPa 的超压，产生应力场。层以 20 度增量倾斜，具有不同的弹性模量，由连续层的刚度比 ( E _U / E _L ) 表示，范围从 0.01 到 100。我们的研究结果验证了先前关于异质地壳模型的研究，表明高刚度比会破坏层内应力并在不匹配的界面处引起局部应力旋转。层倾角进一步影响应力场，在不同距离上移动最大应力集中的位置。这项研究强调了准确了解机械特性、火山层倾角和岩浆室几何形状的重要性。改善对活火山未来喷发口的预测，特别是在地壳变形、折叠和非水平分层的安第斯山脉，取决于这些知识。通过扩展应力模型以纳入复杂的地质结构，我们增强了预测喷发地点和岩浆传播路径的能力。