Passive seismic reflection imaging based on acoustic and elastic reverse time migration without source information: theory and numerical simulations
Passive seismic reflection imaging based on acoustic and elastic reverse time migration without source information: theory and numerical simulations
复制标题
无震源信息的基于声弹性逆时偏移的被动地震反射成像：理论与数值模拟
DOI：
10.1080/08123985.2021.1917293
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发表时间：
2021
影响因子：
0.9
通讯作者：
Watanabe Toshiki
中科院分区：
文献类型：
--
作者：
Shiraishi Kazuya;Watanabe Toshiki
为了利用地震记录探测地壳结构，提出了一种基于逆时偏移（RTM）的无震源地震反射成像新方法。在建议的RTM方法使用表面和地下边界之间的多次反射，我们相关的前向和后向外推波场相同的观测记录，从所有接收器一次。我们实现了基于标量波动方程的声学RTM和基于波场建模的速度-应力公式的弹性RTM。此外，我们采用标量和矢量位公式在弹性RTM获得单独的P和S波反射图像。在我们的研究中，数值模拟与区域地壳结构模型进行了比较合成数据之间的组合声波或弹性波建模，观测条件和RTM配方。我们证明了所提出的方法与理想化的密集观测的有效性，并确认了由于准现实稀疏观测的限制。由弹性合成数据的声学RTM图像中的P波和S波的混合物引起的伪影通过弹性RTM衰减，这解决了P波和S波反射的适当照明。
To explore crustal structures using seismic records of earthquakes, we proposed a new seismic reflection imaging method based on reverse time migration (RTM) without source information. In the proposed RTM method using multiple reflections between surface and subsurface boundaries, we correlate forward- and backward-extrapolated wavefields of the same observation records from all receivers at once. We implemented acoustic RTM based on a scalar wave equation and elastic RTM based on a velocity-stress formulation for wavefield modelling. Furthermore, we adopted scalar and vector potential formulations in elastic RTM to obtain separate P- and S-wave reflection images. In our study, numerical simulations with a regional crustal structure model were conducted to compare combinations among the synthetic data by acoustic or elastic wave modelling, observation conditions, and RTM formulations. We demonstrated the validity of the proposed method with idealised dense observations and confirmed a limitation due to quasi-realistic sparse observations. Artefacts due to the mixture of P- and S-waves in the acoustic RTM images from elastic synthetic data were attenuated by elastic RTM, which addresses the proper illumination of P- and S-wave reflections.