Inversion of the horizontal-to-vertical spectral ratio in presence of strong lateral heterogeneity
Inversion of the horizontal-to-vertical spectral ratio in presence of strong lateral heterogeneity
复制标题
存在强横向异质性时水平与垂直光谱比的反演
DOI：
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
C. Caudron
中科院分区：
文献类型：
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作者：
M. Perton;Z. Spica;C. Caudron
水平垂直比(HVSR)方法最近重新引起了人们的兴趣，因为它通过扩散场方法进行了新的解释。根据这一理论，将HVSR测量与格林函数恢复联系在一起。传统上，HVSR方法用于评价简单的和浅层的速度模型，但我们证明，通过选择合适的数据处理和反演方案，可以评价复杂的地球结构(包括复合地质分层)。特别是，我们通过沿垂直陨石坑壁上的测量来探索强横向非均质性对HVSR的影响。然而，具有横向非均质性的波传播计算在进行反演时效率不高。然后，为了加速正演计算，我们确定了一个由无界二维多层介质组成的简化模型，该模型允许使用修正因子来描述观测到的测量结果。2-D角色来自与垂直吹向陨石坑墙壁的风有关的非标准噪音照明。它得到了几个理论和实验论证的支持。我们还表明，H分量和V分量可以独立地反演，这可能会提高高频下的反演灵敏度。为了减少问题的非唯一性，我们考虑了几个位置的H和HVSR的联合反演，在这些位置，由于大量的地质露头，评估了层的厚度。恢复的速度结构与地质的良好一致性表明，该方法并不局限于无边界的简单浅层构造，这为该方法在勘探地球物理或灾害评估中的应用开辟了领域。
The horizontal-to-vertical spectral ratio (HVSR) method has recently gained a resurgence of interest because of its new interpretation through the diffuse field approach. According to this theory, the HVSR measurement is linked to the Green's function retrieval. While the HVSR method is traditionally used to evaluate simple and shallow velocity model, we demonstrate that complex Earth' structure (that includes composite geological layering) can be assessed by choosing appropriate data processing and inversion scheme. In particular, we explore the effects of a strong lateral heterogeneity on the HVSR by using measurements along a vertical crater wall. However, wave propagation computation with lateral heterogeneity is inefficient to conduct an inversion. Then, to accelerate the forward calculation, we identified a simplified model consisting of an unbounded 2-D multilayer medium that allows describing the observed measurements with the use of a correction factor. The 2-D character comes from a nonstandard noise illumination related to the wind blowing perpendicularly to the crater walls. It is supported by several theoretical and experimental arguments. We also show that the H and V components can be retrieved independently, which may improve the sensitivity of the inversion at high frequency. To reduce the non-uniqueness of the problem, we consider the joint inversion of the H and HVSR's at several positions where the thicknesses of the layers were evaluated thanks to a large geological outcrop. The good agreement between the recovered velocity structure and the geology shows that the method is not limited to unbounded simple shallow structures, which opens the domains of application of the method to exploration geophysics or to hazard assessment.
影响因子：
2.8
作者：
Lontsi, Agostiny Marrios;Jose Sanchez-Sesma, Francisco;Krueger, Frank
通讯作者：
Krueger, Frank