ACTIVE TECTONICS AND EARTHQUAKE ACTIVITIES IN CHINA

In this paper we have studied the relationship between the active tectonics and earthquake activities in China. Active tectonics includes the structures of active faults, active folds, active basins, and active blocks. All earthquakes of magnitude over 8 and most of earthquakes with magnitudes 7 to 7.9 occurred along the boundaries of active tectonic blocks. A few earthquakes of magnitudes 7 to 7.9 and some of those 6 to 6.9 were distributed along the active tectonic zones in the interior of tectonic blocks. Great earthquakes were closely linked with active faults, active folds and active basins; the co-seismic ruptures and displacements of more than 70 historical earthquakes were consistent with these active tectonic zones. Except a few earthquakes occurred in the interior of high mountains and plateau; most earthquakes of magnitudes 7 to 8 occurred along active faults, active folds and active basins. 5%~15% of earthquakes of magnitudes 6 to 6.9 were not associated with active tectonic zones, or their causal relationships with active tectonic zones are unknown. Because the stress environment differs from one tectonic block to another, active tectonic deformation and types of seismogenic structures are also different. In the paper we have discussed the seismogenic models and active structures of strike slip faulting, reverse faulting-folding, and normal faulting-extension in different tectonic block regions.