Volcano deformation models contribute to hazard assessment by simulating magma system dynamics. Traditional magma reservoir pressure source shape assumptions often fail to replicate irregular, geophysically identified geometries. Uncertainties regarding the influence of reservoir geometry can limit the effectiveness of using deformation models to decipher unrest signals. Here, we aim to determine the feasibility of using a magma reservoir geometry directly derived from a seismic tomography survey in a volcano deformation model for Soufrière Hills Volcano, Montserrat. Three-dimensional deformation models are created to simulate displacement using a pressure source geometry constrained from a low seismic velocity anomaly, inferred to be a region of partial melt, and contrasted against a traditional ellipsoid reservoir geometry. We also test a “hybrid” model combining a seismically inferred reservoir upper geometry and ellipsoidal base. Results of each model are evaluated against ground displacement observed on Montserrat from 2010 to 2022. Our results show that different reservoir geometries change the horizontal and vertical displacement fields across the island: the ellipsoid reservoir best reproduces vertical displacement magnitude, while the hybrid reservoirs best simulate horizontal displacement vectors and the region of maximum uplift. Overall, the ellipsoid-shaped reservoir provides our best-fit to the observed data, but we note this result could be biased due to prior years of optimization helping constrain the ellipsoid shape, size, and location. Our results show the potential for further use of geophysically constrained reservoir geometries in deformation modeling, and our methods could be applied to other deforming volcanoes worldwide.

中文翻译：

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在蒙特塞拉特 Soufrière Hills 火山的火山变形模型中使用地震推断的岩浆储层几何形状的影响


火山变形模型通过模拟岩浆系统动力学来促进灾害评估。传统的岩浆储层压力源形状假设通常无法复制不规则的、地球物理识别的几何形状。储层几何形状影响的不确定性会限制使用变形模型破译动荡信号的有效性。在这里，我们旨在确定在蒙特塞拉特 Soufrière Hills 火山的火山变形模型中使用直接从地震层析成像调查得出的岩浆储层几何形状的可行性。创建三维变形模型以使用受低地震速度异常约束的压力源几何形状来模拟位移，该几何形状被推断为部分熔化区域，并与传统的椭球体储层几何形状形成对比。我们还测试了一个结合了地震推断的储层上部几何形状和椭球体基底的“混合”模型。每个模型的结果都根据 2010 年至 2022 年在蒙特塞拉特观察到的地面位移进行评估。我们的结果表明，不同的储层几何形状改变了整个岛屿的水平和垂直位移场：椭球形储层最能再现垂直位移大小，而混合储层最能模拟水平位移矢量和最大隆起区域。总体而言，椭球形储层为我们提供了与观测数据的最佳拟合，但我们注意到，由于前几年的优化有助于限制椭球体的形状、大小和位置，因此此结果可能会有偏差。我们的结果表明，在变形建模中进一步使用地球物理约束的储层几何形状的潜力，我们的方法可以应用于全球其他变形火山。