Minato Shohei, Ghose Ranajit
Department of Geoscience and Engineering, Delft University of Technology, Stevinweg 1, 2628 CN, Delft, The Netherlands.
Sci Rep. 2021 Nov 11;11(1):22073. doi: 10.1038/s41598-021-01199-1.
When using waveform tomography to perform high-resolution imaging of a medium, it is vital to calculate the sensitivity in order to describe how well a model fits a given set of data and how the sensitivity changes with the spatial distribution of the heterogeneities. The traditional principle behind calculating the sensitivity-for detecting small changes-suffers from an inherent limitation in case other structures, not of interest, are present along the wave propagation path. We propose a novel principle that leads to enhanced localization of the sensitivity of the waveform tomography, without having to know the intermediate structures. This new principle emerges from a boundary integral representation which utilizes wave interferences observed at multiple points. When tested on geophysical acoustic wave data, this new principle leads to much better sensitivity localization and detection of small changes in seismic velocities, which were otherwise impossible. Overcoming the insensitivity to a target area, it offers new possibilities for imaging and monitoring small changes in properties, which is critical in a wide range of disciplines and scales.
当使用波形层析成像对介质进行高分辨率成像时，计算灵敏度对于描述模型与给定数据集的拟合程度以及灵敏度如何随非均匀性的空间分布变化至关重要。计算灵敏度背后的传统原理——用于检测微小变化——在波传播路径上存在其他不感兴趣的结构时会受到固有限制。我们提出了一种新原理，该原理可增强波形层析成像灵敏度的定位，而无需了解中间结构。这一新原理源于一种边界积分表示，它利用了在多个点观测到的波干涉。在地球物理声波数据上进行测试时，这一新原理可实现更好的灵敏度定位，并能检测到地震速度的微小变化，而这在其他情况下是不可能的。克服了对目标区域的不敏感性，它为成像和监测属性的微小变化提供了新的可能性，这在广泛的学科和尺度中至关重要。
