Estimation of Coda Wave Attenuation Quality Factor from Seismogram of Local Earthquake

In this research seismic wave attenuation is estimated from the decay rate of coda wave amplitudes of digital seismogram of local earthquake. This event which has been occurred on 26 July, 2003 of 23: 18: 17 UTC time at Daruchari in Chittagong region, Bangladesh. Seismogram of this event has been selected for estimation of coda wave attenuation quality factor (Qc). The coda wave of a seismogram from this local earthquake recorded at Dhaka University seismic station. This seismogram has been analyzed for the purpose of ten central frequencies (0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 3.0, 4.0, 6.0 and 8.0 Hz) and three laps time of total 1000 second, first half of 500 second and last half of 500 second duration. Single backscattering model is used to determine Qc in this work. The estimated frequency dependence quality factors are given the relation, Q_c = 3428.738f^0.854 Q_c = 6393.912f^0.954 and Q_c = 6886.847f^0.917 respectively. The observed coda quality factors are not strongly dependent on frequency, which indicates that the region is not seismic and tectonically active with high heterogeneities.