The effects of topography on magma chamber deformation models: Application to Mt. Etna and radar interferometry
The effects of topography on magma chamber deformation models: Application to Mt. Etna and radar interferometry
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DOI：
10.1029/98gl01136
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发表时间：
1998-05
影响因子：
5.2
通讯作者：
C. Williams;G. Wadge
中科院分区：
文献类型：
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作者：
C. Williams;G. Wadge
我们使用一个三维弹性有限元模型来检验地形对由岩浆房收缩模型预测的地表变形的影响。我们使用埃特纳火山的地形来控制模型的几何形状，并将有限元结果与弹性半空间中受压球体的解析解预测结果进行了比较。地形对位移剖面和合成干涉图的地表变形预测都有显著影响。不仅预测的位移幅度有显著差异，而且位移的地图-视图模式也有显著差异。通过调整参考面标高，可以很好地匹配预测的位移幅度；然而，水平变形模式仍有显著差异。因此，基于等高程参考面的反演可能无法正确估计岩浆库的水平位置。我们研究了一种方法，其中每个计算点的参考面高程变化，对应于地形。对于垂直位移和倾斜，该方法可以很好地拟合有限元结果，因此可以形成反演方案的基础。对于径向位移，恒定的参考标高可以更好地拟合数值结果。
We have used a three‐dimensional elastic finite element model to examine the effects of topography on the surface deformation predicted by models of magma chamber deflation. We used the topography of Mt. Etna to control the geometry of our model, and compared the finite element results to those predicted by an analytical solution for a pressurized sphere in an elastic half‐space. Topography has a significant effect on the predicted surface deformation for both displacement profiles and synthetic interferograms. Not only are the predicted displacement magnitudes significantly different, but also the map‐view patterns of displacement. It is possible to match the predicted displacement magnitudes fairly well by adjusting the elevation of a reference surface; however, the horizontal pattern of deformation is still significantly different. Thus, inversions based on constant‐elevation reference surfaces may not properly estimate the horizontal position of a magma chamber. We have investigated an approach where the elevation of the reference surface varies for each computation point, corresponding to topography. For vertical displacements and tilts this method provides a good fit to the finite element results, and thus may form the basis for an inversion scheme. For radial displacements, a constant reference elevation provides a better fit to the numerical results.