2005年云南文山地震余震序列尾波Qc值研究

基于Aki等（1975）的地方震尾波单次散射模型，利用文山地震台记录到2005年8月13日在云南文山县发生的5.3级地震余震序列的数字化波形观测资料，测量了震源区尾波Q（f）值。测量结果表明，当中心频率为1．5Hz时，文山地区的尾波Q值在52～155之间，平均值为91，尾波的振幅衰减率β（f）在0.013～0．039之间，平均值为0．024；测量得到该区尾波Qc值与频率f的关系为Qc（f）=62f^“0.87；尾波波源因子A0与震级ML成正比关系，满足关系lgA0=1．02ML-0．73。此次地震的发震构造为文山断裂带，地震波受到破碎带强烈的非弹性吸收，尾波Qc值明显降低。

Study on the Qc value of coda for sequence of aftershocks of Wenshan earthquake in Yunnan Province in 2005

Based on the single scattering theory of coda waves for local earthquakes suggested by Aki and Chouet, using the digital data for aftershock sequence of Wenshan earthquake of Yunnan Province in 2005 recorded by Wenshan Seismic Station, the Qc value of coda at the source region has been estimated. The Qc value of coda waves at Wenshan region is in the range of 51～147 and the average is 79 when center frequency f=l. 5 Hz. The amplitude attenuation ratio fl（f） is in the range of 0. 014～0.0a9 and the average is 0. 028; It was obtained that the relationship between coda Qc and frequency f is Qc（f）= S af 0 88 in this area; The coda factor is direct proportion to magnitude, being satisfactory to lgA0 =151ML-0.94 , and is inverse proportion to frequency, being satisfactory to lgA0=-0. 073f＋2.60; the results show that coda Qc value for aftershock sequence of Wenshan earthquake is lower, which is the type of unstable tectonic environment area.