We would like to thank Jingye Li, Jiang Yuan, Zhaoyu Jin, Keling Chen, Pan Deng, James Rickett, Jonathan Blair Ajo-Franklin and two anonymous reviewers for helpful comments and suggestions. Yangkang Chen would like to thank Sergey Fomel for inspiring discussions on the local similarity algorithm and the Texas Consortium for Computational Seismology (TCCS) for financial support. This paper and all the figures are prepared with the Madagascar software package, which is an open-source research environment for reproducible computational experiments (Fomel et al., 2013).