We would like to thank Ming Zhang, Zhaoyu Jin, Shaohuan Zu, Shuwei Gan for constructive suggestions and fruitful discussions that improve the manuscript and Matlab codes greatly. This work is partially supported by Texas Consortium for Computational Seismology (TCCS) and the National Basic Research Program of China (grant NO: 2013 CB228602) and Sinopec Key Laboratory of Geophysics (Grant No. 33550006-15-FW2099-0017).