Detecting the Earth’s Interior Structure Using Reverse-Time Migration Based on Wavefield Normalized Cross-Correlation Imaging Condition

Lei Yang, Gregory C. Beroza, & Liang Zhao

Submitted August 15, 2018, SCEC Contribution #8709, 2018 SCEC Annual Meeting Poster #109

Increasingly dense arrays are being deployed globally and new imaging methods are being developed to constrain the fine details of the earth’s interior structure. In this study, we apply reverse-time migration (RTM), which is the most accurate migration method in exploration geophysics, to the detection of the earth’s interior. RTM is based on the two-way wave equations, and it directly exploits the full waveform information from the seismic data without phase picking. It doesn’t assume horizontal interfaces, and has potentially good resolution for interfaces with large dips. Thus, RTM provides more accurate imaging results than the traditional ray-based seismic imaging and receiver function methods. To implement RTM, we perform forward modeling, backward modeling and use the source wavefield normalized cross-correlation imaging condition to obtain the imaging results. For teleseismic events, hybrid method is adopted for an efficient forward wavefield modeling by combining generalized ray theory for far-field seismic wave propagation and finite difference for local numerical simulation. Additionally, imaging results from different earthquake events are stacked together to improve the signal noise ratio. Compared with the existing passive RTM method based on the converted wave imaging condition, the new RTM method can better determine the stacking weighting coefficients for different seismic events, and it does not need a separation of P and S wave. Synthetic experiments demonstrate the capacity of the new method for imaging the fine details of the complex structure in the deep earth.

Citation
Yang, L., Beroza, G. C., & Zhao, L. (2018, 08). Detecting the Earth’s Interior Structure Using Reverse-Time Migration Based on Wavefield Normalized Cross-Correlation Imaging Condition. Poster Presentation at 2018 SCEC Annual Meeting.


Related Projects & Working Groups
Seismology