Source Time Function of Caspian Basin and Surrounding Area Earthquakes

Document Type : Seismology and Engineering Seismology




The south Caspian Basin is a seismic block within the Alpine-Himalayan Belt. The source time function of 31 events of Caspian earthquakes have been obtained from teleseismic body waveform modeling. The duration of each subevent with magnitude larger than 5 (Mw>5.0) and depth between 4 £ h £ 76km was determined from source time function. Corner frequency and stress drops have been calculated for each of 31 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 = (0.2642 ± 0.001) log MO-8.9119 ( ± .0.194). Corner frequencies range is from 0.038Hz to 0.16Hz. Static stress drops calculated from the pulse shapes for each event studied in this paper changed between 0.07 bars to a maximum of 46 bars. Minimum and maximum displacements are 0.79m and 3.3m 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.