THE CODA WAVE ATTENUATION CHARACTERISTICS IN 1830 CIXIAN,M7.5 EARTHQUAKE AREA

Based on digital waveform data of local earthquakes,using coda Aki single scattering model the coda Q_c value of stations around 50 km in 1830 CiXian,M7.5 earthquake region are calculated through seismic casualties fitting.The result indicate that when lapse time is 20 s,the coda Q_c is: Q_c=(70.2±29.3)f^{(0.8054±0.1615)};when the lapse is 40 s,the coda Q_c is: Q_c=(96.6±25.3)f^{(0.777 2±0.109 8)}.The results show that Q_c value of coda is lower and the attenuation of seismic waves in Cixian'seismic area are faster than that in Xingtai,Tangshan Earthquake area;η values show that the dependence of Q_c value to frequency is weaker than that in the Xingtai and Tangshan earthquake area.