Research on characteristics of magnitude structure of earthquake sequences

Abstract

Based on the research on 108 strictly selected earthquake sequences since 1965 in the Chinese mainland, why the magnitude structures of most of these sequences are not in accord with the G-R relation has been analyzed and the fitting method with the division of the magnitude structure for the earthquake sequences has been suggested. The characteristic values of this method in the high magnitude interval have mainly been researched, and characteristic magnitude percentf and the slope ratiob ₂ of the high magnitude interval, which are different for various sequence types are most obvious. The results show that theN-M patterns of magnitude structures for 52.8% earthquake sequences are not in accord with the G-R relation from the magnitude less than 80% of the maximum one and that for only 18.5% earthquake sequences show the decrease trend in the high magnitude interval. Whenb ₂<0 or 0≤b ₂<3.0 andf is less, the strong aftershocks in the earthquake sequences are less; whenb ₂≥3.0 for the sequence, several strong aftershocks often occurred; when 0≤b ₂<3.0 andf is bigger, aftershocks with middle magnitude are more in these sequences.