The tectonic deformations and seismic activites of 26 active boundary zones are studied based on the delineation and studies on active tectonic blocks in the continent of China, these 26 active boundary zones are located in 6 active tectonic block regions and 22 active tectonic blocks. The relationship of distribution of major earthquakes with active boundary zones, the relationship of tectonic movement rate with the level of seismic activities in boundary zones and the relationship of tectonic movement rate with recurrence periods of strong earthquakes in boundary zones, etc., are studied in the paper. The linear relation between tectonic movement rate and seismic activities and the reverse relation of tectonic movement rate and recurrence interval of strong earthquakes are presented. The results reveal the tectonic characteristics and motion characteristics of active tectonic blocks in the continent of China, and indicate that the activity of strong earthquakes is controlled by the tectonic deformation of block boundary zones.

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More than 28,000 aftershocks have occurred since the 05/12/2008 Wenchuan earthquake, with dozens of them stronger than M 5. Since July, 2008, all the M > 5 earthquakes have occurred only in the northern segment of the rupture zone, suggesting obvious seismicity segmentation. We applied the double difference method to relocate all of the M > 3 aftershocks. After relocation, the aftershocks show a compact zone of seismicity, with a length of about 300 km and average width of 30 km, supporting that the hypothesis that the Beichuan-Yingxiu and Chaping-Linjiaan faults are the faults that ruptured in the earthquake. With the Cut and Paste (CAP) waveform inversion algorithm, we determined the source mechanism and focal depth of all the > M 5 aftershocks in the northern segments. The number of thrust events is close to the number of strike-slip events, but almost all of the events with thrust mechanism are distributed over the northern segment, while the aftershocks with strike-slip mechanism only occurred at the north-easternmost end, contrasting with eld observations of a substantial strikeslip component of surface rupture over the northern segment. The events with strike-slip mechanism occurred at depths up to 18 km, consistent with the lack of surface rupture in the north-easternmost section. However, since early August, very shallow events (2 km) with thrust mechanism have occurred, probably releasing the strain energy of the unruptured fault in the north-easternmost section. It seems that the seismic hazard potential of the northern segment is still quite high, and more studies are needed to resolve some of the discrepancy suggested by aftershock patterns and other observations.

We have selected 27530 ML amplitude readings from 5897 events recorded by 149 stations, as reported in the Annual Bulletin of Chinese Earthquakes (ABCE) and regional seismic network of Yunnan province and Sichuan province, and have used tomographic imaging to estimate the lateral variations of the quality factor Q0 (Q at 1Hz) in the crust of Sichuan‐Yunnan and its adjacent regions. Estimated Q0 values vary from 200 to 600 with an average of 400. Q0 value is consistent with tectonic and topographic structure. Q0 is low in the active tectonic regions having many faults, such as the Haiyuan‐Qilian, Fenhe‐Weihe, East Kunlun zones, Western Sichuan‐Northwestern Yunnan‐Baoshan area, and Yunnan and Guizhou boundary‐Kunming‐Simao area. Q0 is high in the stable regions, such as Sichuan Basin, Markam block, Western Guangxi‐Eastern Yunnan block, Ordos Craton, and Qinling‐Dabie area. Additionally, the gains of most of the station terms in Sichuan‐Yunnan and its adjacent regions are near 1.0, only a few as large as 2.0, and the distribution is irregular. Most of the magnitude biases are less than 0.3, only a few as large as 0.4, and the distribution has relation with Q0 value variation, which means that the seismic attenuation has influence on the magnitude measurement.