• ISSN 2097-1893
  • CN 10-1855/P

地震干涉自相关成像方法及应用进展

Research progress on the seismic interferometric auto-correlation imaging method

  • 摘要: 地震干涉自相关成像方法利用单个地震台站记录的天然地震事件或背景噪声数据的自相关叠加来获得台站下方的自激自收剖面,已被广泛应用于地球内部结构成像,并被推广至月球和火星结构探测. 该方法仅利用单个地震台站,避免了台站间时钟同步的限制,还可以仅使用单个分量实现对地下结构的成像,使得实际使用更加方便灵活. 地震干涉自相关成像方法又被称为广义接收函数或垂向接收函数,相比于传统的接收函数,其可以利用更高、更宽频带的天然地震或背景噪声信号,对地球内部间断面的刻画具有更高的垂向分辨率,同时受多次波的影响更弱. 目前该方法已成功应用于探测地球内部的主要不连续界面,包括莫霍面、岩石圈内部不连续面、海尔斯不连续面、岩石圈—软流圈边界和莱曼不连续面. 另外,该方法还被用于探测地球内核的各向异性. 本文简要回顾了地震干涉自相关方法的发展历程,重点介绍了其基本原理和数据处理流程. 谱白化在自相关处理中具有至关重要的作用,相位加权叠加可以有效提高叠加结果信噪比,增强对相干性较好的微弱反射信号的识别能力. 在此基础上,详细梳理了地震干涉自相关方法在利用全球地震震相、远震地震震相、区域和近震震相以及背景噪声等方面的研究进展. 最后,对存在的问题和可能的解决思路进行了简要讨论,并结合地震学发展趋势对未来发展方向进行了探讨.

     

    Abstract: The seismic interferometric auto-correlation imaging method reconstructs virtual zero-offset reflection response beneath a single seismic station by stacking the auto-correlation of earthquakes or ambient noise. This technique has gained increasing attention for its capability to image Earth's interior structures, and has also been extended to studies of the Moon and the Mars. Relying solely on single-station records, it circumvents the need for inter-station synchronization and allows imaging using single component seismic data, enhancing operational flexibility. The auto-correlation imaging method, also known as the generalized receiver function or vertical receiver function, offers distinct advantages over conventional receiver functions. By utilizing frequency components with higher and broader-bandwidth from earthquakes or ambient noise, it achieves improved vertical resolution for imaging subsurface discontinuities. Moreover, it is less affected by multiple scattering phases, enhancing its robustness in complex geological environments. This method has been used to efficiently identify the major discontinuities in the Earth's interior, including the Moho, mid-lithospheric discontinuity, Hales discontinuity, lithosphere-asthenosphere boundary, and Lehmann discontinuity. In addition, it has been used to probe the anisotropy of the Earth's inner core. First, we briefly summarize the historical development of the auto-correlation imaging method. Second, we focus on its fundamental principles and processing workflows. Spectral whitening plays a key role in improving the auto-correlation imaging results. Phase-weighted stacking is a valuable procedure to enhance the signal-to-noise ratio and help to more easily identify weak yet important reflections with high coherence. Third, we outline recent advances in applications involving global, teleseismic, regional, and local earthquake events, as well as ambient noise in more detail. In the end, key challenges and potential solutions are discussed, and future directions are explored in the context of emerging trends in earthquake seismology.

     

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