Simultaneous inversion of surface deformation and gravity changes by means of extended bodies with a free geometry: Application to deforming calderas
Simultaneous inversion of surface deformation and gravity changes by means of extended bodies with a free geometry: Application to deforming calderas
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DOI：
10.1029/2010jb008165
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发表时间：
2011-10-05
影响因子：
3.9
通讯作者：
Berrino, Giovanna
中科院分区：
文献类型：
--
作者：
Camacho, Antonio G.;Gonzalez, Pablo J.;Berrino, Giovanna
重力和/或地表形变的变化往往与火山活动有关。通常，考虑到异常质量和/或压力变化，使用具有简单几何形状的物体(例如，点源、长椭球或扁球体)来模拟这些信号。我们提出了一种利用自由几何物体同时进行重力变化和地表形变的非线性反演的新方法。假定简单的均匀弹性条件，该方法确定了压力源和密度源的一般几何构形。这些源被描述为压力和密度点源的集合，符合整个数据集(给定一些规律性条件)。这种方法是一种循序渐进的增长过程，允许我们构建非常一般的几何配置。对埋藏在弹性介质中的具有反常压力的椭球体和具有反常密度的平行六面体进行了验证。形变值和重力值的同时反演可以很好地重建假设的物体。最后，将该方法应用于意大利Flegrei Campi火山区1992-2000年重力、水准和干涉合成孔径雷达(InSAR)资料的解释。对于这一时期，一个没有明显质量变化和一个扩展的降压区的模型令人满意地拟合了数据。压力源位于大约1500m深处，它被解释为对应于局限于火山口充填物的浅层(深度1-2公里)热液系统的动力学。
Changes in gravity and/or surface deformation are often associated with volcanic activity. Usually, bodies with simple geometry (e. g., point sources, prolate or oblate spheroids) are used to model these signals considering anomalous mass and/or pressure variations. We present a new method for the simultaneous, nonlinear inversion of gravity changes and surface deformation using bodies with a free geometry. Assuming simple homogenous elastic conditions, the method determines a general geometrical configuration of pressure and density sources. These sources are described as an aggregate of pressure and density point sources, fitting the whole data set (given some regularity conditions). The approach works in a growth step-by-step process that allows us to build very general geometrical configurations. The methodology is validated against an ellipsoidal body with anomalous pressure and a parallelepiped body with anomalous density, buried in an elastic medium. The simultaneous inversion of deformation and gravity values permits a good reconstruction of the assumed bodies. Finally, the inversion method is applied to the interpretation of gravity, leveling, and interferometric synthetic aperture radar (InSAR) data from the volcanic area of Campi Flegrei (Italy) for the period 1992-2000. For this period, a model with no significant mass change and an extended decreasing pressure region satisfactorily fits the data. The pressure source is located at about similar to 1500 m depth, and it is interpreted as corresponding to the dynamics of the shallow (depth 1-2 km) hydrothermal system confined to the caldera fill materials.