%0 Journal Article
%T Estimation of Coda Wave Attenuation Quality Factor from Digital Seismogram Using Statistical Approach
%J Science and Technology
%@ 2163-2677
%D 2012
%I 
%R 10.5923/j.scit.20120201.01
%X The main objective of the paper is to estimate seismic wave attenuation from the decay rate of coda wave amplitudes of digital seismogram of local earthquakes (epicentral distance < 100 km) following statistical approach. Three earthquake events have been selected for estimation of coda wave attenuation quality factor (Qc). The coda wave of 9 seismograms from 3 local earthquakes recorded digitally by three seismic stations in the region have been analyzed for this purpose at ten central frequencies (1, 1.5, 2, 3, 4, 6, 8, 12, 16 and 18Hz) and three lapse time windows of 20, 30 and 40 seconds duration. Single backscattering model proposed by Aki (1969) and extended by Aki and Chouet (1975) and Sato (1977) is employed to determine Qc values. The mean values of the estimated Qc vary from 31+12 (at 1Hz) to 1974+211 (at 18Hz) for 20 seconds coda window length. For 30 seconds coda window length Qc vary from 46+16 (at 1Hz) to 1977+ 256(at 18Hz). Similarly for 40 seconds coda window length Qc vary from 97+ 22 to 2552 +312. It is observed that Qc value for the study area is frequency dependent and increase with increase in frequency. Moreover the observed Qc values increase with increasing lapse time at all frequency bands. The estimated Qc values show a frequency dependent relationship of the form Qc=Qof n, where Q0 is Qc at 1Hz and n represents degree of frequency dependence. The frequency dependent empirical attenuation relationship for 20, 30 and 40 seconds window lengths are obtained as Qc = 21.49+1.17 f 1.48+0.08, Qc = 48.6+1.11 f 1.29+0.06 and Qc = 88.86+1.12 f 1.19+0.06 respectively.
%K Earthquake
%K Seismogram
%K Coda Waves
%K Central Frequency
%K Epicentral Distance
%K Local Earthquake
%U http://article.sapub.org/10.5923.j.scit.20120201.01.html