Abstract: Based on their size,total displacement and tectonic style,basins of the Fenwei graben system(northeast of China) can be divided into four types,the infant(or initial),the young(or growing),the mature and the joining ones,each succeeding stage being developed from the preceding one.
From the infant basin through the young or the mature,there was a decline in the structure barrier(or the resistance of the basin to further depression or expansion) resulting in a decrease of the upper limit of earthquake magnitude.