ANALYSES FOR SEISMOTECTONICS OF INTRAPLATE BASINS: AN EXAMPLE OF SOUTHERN JIANGSU PROVINCE

The main controlling factors of intraplate earthquakes are the regional tectonic stress field and the special conditions for the seismogenic structures. It is suggested that the most important indictors for the moderately strong earthquakes in southern Jiangsu province are the active basins of the Cenozoic era. The buried seismogenic faults within the basins are suitably oriented with respect to the maximum stress of the regional tectonic stress field which is favour of shear ruptures. Results of three dimensional numerical modeling by the finite element method demonstrate that the weakened zone of the crust in thebasins could give rise to redistribution and local accumulation of the tectonic stress. The buried faults re-lated to the zone of weakeness in the basins may be the potential sites of seismic ruptures. The elasticstrain energy built up near the edges of the basin can be the driving force for occurrence of earthquakes.