**5. Conclusions**

We have presented a new ERTM technique to produce the weakly illuminated structure. To extract the elastic wavefield related to the target, a stained vector-decoupled wave equation is adopted. The filter in the inner product imaging condition can suppress the migration artifact, improving the resolution of ERTM results. Numerical results show that our method can generate better amplitude for the weakly illuminated structure, providing possible technical support for reducing the risk of hydrocarbon development.

**Author Contributions:** Conceptualization, Y.S. and L.S.; methodology, Y.S.; software, W.L.; validation, Y.S. and L.S.; formal analysis, W.L.; investigation, L.S.; resources, Y.S.; data curation, Y.S.; writing—original draft preparation, L.S.; writing—review and editing, L.S.; visualization, W.L.; supervision, Y.S. and Q.Z.; project administration, Y.S. and Q.Z.; funding acquisition, Y.S. and L.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Natural Science Foundation of China (U19B6003- 004), the National Key R&D Program of China (2018YFA0702505), the National Natural Science Foundation of China (41930431) and the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province (Grant No. UNPYSCT-2020149).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
