Point spread functions for earthquake source imaging: an interpretation based on seismic interferometry
Point spread functions for earthquake source imaging: an interpretation based on seismic interferometry
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DOI：
10.1093/gji/ggv109
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发表时间：
2015-07
影响因子：
2.8
通讯作者：
H. Nakahara;M. Haney
中科院分区：
文献类型：
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作者：
H. Nakahara;M. Haney
近年来，人们提出并应用了多种震源成像方法，并对各种方法之间的理论关系进行了研究。在本研究中，我们进行了后续的理论研究，以更好地理解震源成像的意义。对于成像问题，点扩展函数（PSF）用于描述作为成像系统响应的目标物体图像的模糊和退化程度。在本研究中，我们建立了用于震源成像的psf。通过对PSF的计算，我们发现波形源反演方法消除了PSF的影响，并且没有伪影。然而，其他源成像方法受到PSF的影响，并且由于接收器分布的限制而遭受模糊和退化的影响。因此，在使用除波形反转以外的源成像方法时，必须仔细处理该效应。此外，利用格林函数的源-接收机互易性，发现震源成像的PSF与地震干涉测量有联系。特别地，对于接收器被分布到完全包围源的情况，PSF可以与格林函数相关。此外，PSF充当低通滤波器。考虑到这些因素，PSF对于理解震源成像的物理意义非常有用。
SUMMARY Recently, various methods have been proposed and applied for earthquake source imaging, and theoretical relationships among the methods have been studied. In this study, we make a follow-up theoretical study to better understand the meanings of earthquake source imaging. For imaging problems, the point spread function (PSF) is used to describe the degree of blurring and degradation in an obtained image of a target object as a response of an imaging system. In this study, we formulate PSFs for earthquake source imaging. By calculating the PSFs, we find that waveform source inversion methods remove the effect of the PSF and are free from artefacts. However, the other source imaging methods are affected by the PSF and suffer from the effect of blurring and degradation due to the restricted distribution of receivers. Consequently, careful treatment of the effect is necessary when using the source imaging methods other than waveform inversions. Moreover, the PSF for source imaging is found to have a link with seismic interferometry with the help of the source–receiver reciprocity of Green’s functions. In particular, the PSF can be related to Green’s function for cases in which receivers are distributed so as to completely surround the sources. Furthermore, the PSF acts as a low-pass filter. Given these considerations, the PSF is quite useful for understanding the physical meaning of earthquake source imaging.