Editorial: Reverse Time Imaging in Solid Earth and Exploration Geophysics

Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX, United States, Key Lab of Submarine Geosciences and Prospecting Techniques MOE, College of Marine Geosciences, Ocean University of China, Qingdao, China, Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen, China, Department of Physics and Department of Earth Sciences, University of Toronto, Toronto, ON, Canada


SUMMARY OF THE PAPERS
The modeling approach enables RTI to map a multitude of seismic sources that were excited in the same time span and at nearby locations, and allows RTM to take multiple scattering wavefields as signals rather than noises. Zhang et al. present here a least-squares RTM (LSRTM) using multiples of OBN data and suppressing crosstalk of multiple wavefields with numerical examples. Zheng et al. take surface multiples in a field walkaway VSP data as the input signal to RTM for monitoring CO 2 injection in NW China, via wavefield decomposition and an inverse scattering imaging condition. He et al. propose a P-SV converted-wave RTM via 1st-order velocity-dilatation rotation of multi-

STATUS OF THE TOPIC
The common occurrence of imaging artifacts and position errors in seismic images based on field data inspires seismic imaging research toward high fidelity, which specifies how accurately each imaging target is resolved at the correct location. To achieve this goal, researchers are making low-frequency vibroseis sources, deploying dense and broadband seismic arrays, developing more advanced and effective numerical simulation algorithms to model seismic wave propagation under more realistic physical conditions, proposing more robust inversion and imaging methods for large volume datasets, and adapting artificial intelligent techniques into seismic imaging. Clearly, the expansion of seismic imaging from high resolution toward high fidelity is an exciting and challenging process. The challenges usually include limited quality and quantity of field data, and more importantly the lack of evidence for verifying imaged features. We expect more interdisciplinary studies to bring in independent evidences for cross checking and corroborating seismic images at processing and interpretation stages.

FUTURE PERSPECTIVES
The desire to better live with our mother Earth demands new ways to overcome the challenges for exploring its interior, and assessing the intricate relationship between our activities of extracting natural resources and the impacts on the environment. We hope the exemplary studies presented here can motivate new research in reverse time imaging, toward providing higher fidelity seismic images for a wider spectrum of applications.

AUTHOR CONTRIBUTIONS
Editorial written by HZ, edited, modified by all other guest editors.
Conflict of Interest: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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