Source Time Function of Caspian Basin and Surrounding Area Earthquakes

The south Caspian Basin is a seismic block within the Alpine-Himalayan Belt. The source time function of ۳۱ events of Caspian earthquakes have been obtained from teleseismic body waveform modeling. The duration of each subevent with magnitude larger than ۵ (Mw>۵.۰) and depth between ۴ £ h £ ۷۶km was determined from source time function. Corner frequency and stress drops have been calculated for each of ۳۱ events by using pulse duration from source time function.When viewed over the entire depth range, the total duration ( ) tt is related to Mo by log tt = (۰.۲۶۴۲ ± ۰.۰۰۱) log MO-۸.۹۱۱۹ ( ± .۰.۱۹۴). Corner frequencies range is from ۰.۰۳۸Hz to ۰.۱۶Hz. Static stress drops calculated from the pulse shapes for each event studied in this paper changed between ۰.۰۷ bars to a maximum of ۴۶ bars. Minimum and maximum displacements are ۰.۷۹m and ۳.۳m respectively. The variation in stress drop is considerable, but no evidence is seen for a scaling relation in which stress drop increase with moment. These relative source durations do not show any clear depth dependence.

Keywords:

Source Time Function , Caspian Sea , Continental Plates , Waveform Modeling