重庆武隆地区地震尾波Q_(C)值特征

Characteristics of Seismic Coda Wave Q_(C) Value in Wulong Area,Chongqing

为了了解重庆武隆地区地下介质的物性特征,为预测强地面运动和评估地震灾害损失提供一定的参考。本文选取2012年1月至2022年12月重庆地震台网记录的武隆地区56次M_(L)≥2.0地震波形资料,采用Sato单次散射模型分别计算了5个台站记录的尾波衰减参数,拟合得到武隆地区地震尾波Q_(C)值与频率(f)的依赖关系为Q_(C)(f)=41.87±8.69f^(0.9568±0.0904),表明该地区为低Q_(0)值(f=1)和较高频率依赖性(η)的构造活跃区。本文还分析了整个地震序列的尾波Q_(C)和η值随时间的变化,发现在2017年武隆M_S5.0地震发生后,WUL和LAX台站记录的Q_(0)和η值存在短期的异常变化,Q_(0)值呈“V”形态,η值呈倒“V”形态,η与Q_(0)值呈反向变化,Q_(0)值经历下降-上升的快速调整过程,表明该区构造活动处于活跃期。

We selected the waveform data of 56 earthquakes with M_(L)≥2.0 between January 2012 and December 2022 recorded by the Chongqing Digital Seismic Network in Wulong area.The Sato single scattering model was used to calculate the coda attenuation parameters of 5 station records.The fitting showed that the dependence of the coda Q_(C) value on frequency in Wulong area was Q_(C)(f)=41.87±8.69f^(0.9568±0.0904),which indicates that the area is a structurally active area with low Q_(0) value(f=1)and high frequency dependence(η).We also analyzed the coda Q_(C) andηvalue changes in time.After the Wulong MS5.0 earthquake in 2017,there was a short-term abnormal change in the Q_(0) andηvalue recorded by WUL and LAX stations.Specifically,the Q_(0) value shows a“V”shape,whereas theηvalue shows an inverted“V”shape.Theηvalue varies inversely with the Q_(0) value,while the Q_(0) value undergoes a rapid adjustment through the decrease-increase process,indicating that the tectonic activity in the area is active.