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利用云南大姚地震台记录到的2009年姚安6.0级地震余震序列的数字化波形观测资料,基于尾波单次散射理论,估算该次地震震源区尾波Qc值。结果表明:中心频率为1.5 Hz时,振幅衰减率β(f)在-0.141 27～-0.043 05之间,平均值为-0.074 60;Qc值在33.3～99.8之间,平均值为65.5。并得出Qc值与频率的关系:尾波波源因子与震级成正比,与频率成反比。主震发生后头几天,尾波Qc值(1.5 Hz)波动较大,之后在±1.5倍方差线内趋于稳定,且没有超过5级的强余震发生。姚安地区尾波Qc值具有构造运动活跃、地震活动频繁地区的低Qc值特征。
Using the digital waveform observation data of the 2009 aftershocks of Yao’an magnitude 6.0 earthquake recorded by the Dayao Seismic Station in Yunnan Province, the coda Qc values of the focal region of the earthquake were estimated based on the single-scattering coda wave theory. The results show that when the center frequency is 1.5 Hz, the amplitude decay rate β (f) is between -0.141 27 and -0.043 05, the average value is -0.074 60; the Qc value is between 33.3 and 99.8 and the average value is 65.5. And draw the relationship between Qc value and frequency: coda wave source factor is proportional to the magnitude and inversely proportional to the frequency. In the first few days after the main shock, the Qc value (1.5 Hz) of the wake wave fluctuated greatly, then stabilized within ± 1.5 times of the variance line, and no strong aftershock exceeding Grade 5 occurred. The Qo value of coda in Yao’an area has the characteristics of low Qc value with tectonic activity and frequent seismic activity.