The moment tensor solution, source time function and spatial-temporal rupture process of the MS6.4 earthquake, which occurred in Ning’er, Yunnan Province, are obtained by inverting the broadband waveform data of 20 global stations. The inverted result shows that the scalar seismic moment is 5.51×1018 Nm, which corresponds to a moment magnitude of MW 6.4. The correspondent best double couple solution results in two nodal planes of strike 152°/dip 54°/rake 166°, and strike 250°/dip 79°/ rake 37°, respectively. Considering the isoseismals and geological structures in the meizoseismal region, the first nodal plane (strike 152°/ dip 54°/ rake 166°) is preferred to be the seismogenic fault. Thus, the MS6.4 earthquake occurred mainly along a right-lateral fault striking 152°. The source time function shows that the duration time of the earthquake is about 14 s. The most of the energy releases within the first 11 s and in 11-14 s the rupture is weak. The snapshots of the slip-rate indicate that the rupture process has 3 more detailed stages. In the first stage of the first 4 s after rupture initiation, the rupture propagates simultaneously toward both strike and dip directions; in the second stage of the following 3 s, the rupture extends to down-dip direction; and in the third stage, the rupture looks to be scattering on the fault. In general, this earthquake is of bilateral rupture, and the rupture mainly takes place in strike-dip direction. The major ruptured area is in the shape of a diamond with a dimension of 19 km. On the whole fault plane, the maximum slip is about 1.2 m, the average slip is about 0.1 m, the maxi-mum slip-rate is 0.4 m/s and the average slip-rate is 0.1 m/s. The features of the co-seismic theoretical displacement field of the Ning’er earthquake fault, calculated based on the inverted fault parameters, are consistent with those of the observed isoseismals.
Three strong earthquakes with magnitudes of MW 8.4, MW 7.9 and MW 7.0 occurred in the sea west of Sumatra Island on September 12 and 13, 2007. We relocated the epicenters and focal depths of the three events by means of the reversal-time imaging technique using broadband digital seismic data from worldwide stations ranging from 30° to 90°, imaged the spatiotemporal variation of the energy radiation sources by means of the nonplane wave array technique using the broadband digital seismic data from a generalized array made up of 33 stations of the Capital Region Digital Seismograph Net-work (CRDSN), and obtained the rupture duration times, extents and rupture velocities. Also, we dis-cussed the correlations between the locations of the energy radiation sources of the three events.
