Based on a 3-D global velocity structure model, the authors used teleseismic P wave data from Asian and South American array to image the rupture process of 2016 Mw 7.8 New Zealand earthquake via backprojection analysis. The results show that the rupture is a unilateral one with northeast direction, extending to the ocean. The rupture speed is about 1.65 km/s. There are two phases dominated by high frequency power radiation, occurring during 20−40 s and 60−80 s, respectively. The second phase is the major one, whose distribution of low frequency power radiation is consistent with the centroid location of the event. The high frequency back projection result of the South American data is better correlated with the peak ground acceleration result. According to the comparison and analysis of the Asian and South American results, it could be inferred that in order to obtain more detailed rupture information of high frequency, the data of array deployed in the region with lower 3-D heterogeneity should be adopted in back projection analysis to enhance the coherency of waveforms.

The lower lateral spectral resolution is caused by the divergence of energy clots in the velocity and effective anisotropic parameter spectra when standard semblance operator is used. To solve the problem, the deterministic trace resorting differential semblance operator is introduced. By resorting the seismic traces, the differential semblance operator is sensitive to the moveout between the adjacent seismic traces, which maximize the spectral resolution. This method could be firstly applied to effective anisotropic parameter analysis using nonhyperbolic traveltime. The synthetic and field data examples are introduced to testify the efficiency of the new method, and the results confirm that spectral resolution increases a lot compared with standard semblance method.