宁夏地区Lg波衰减及场地响应特征

本文采用2008—2017年宁夏及邻区内15个数字地震台站记录的131次地震的波形资料，基于地震波衰减与场地响应联合反演方法，分析频率介于1—7 Hz之间的Lg波衰减及场地响应。采用2.2—3.6 km/s的速度窗截取了1 069条Lg波，计算得到Lg波各分量的地震波衰减品质因子Q（ f ）与频率f之间的关系。结果显示:Lg波垂直、东西及南北向各分量的Q₀分别为237.1，201.8及245.9；Q（ f ）对f的依赖性指数分别为0.44，0.52及0.44，该结果与全球其它地震活跃地区的相应研究结果相一致。对Q（ f ）在时间域的分析结果表明，研究时段内该地区地壳介质的衰减属性并未改变，15个台站的最大场地响应幅值不大于6。 

Lg-wave attenuation and site response in Ningxia region

Based on 131 seismic waveform data recorded by 15 digital seismic stations in Ningxia region and its neighboring areas from 2008 to 2017, this paper analyzed Lg wave attenu-ation and site response at the frequencies ranging from 1 to 7 Hz by using the combined?inversion?method?of?seismic?wave?attenuation and?site?response. The relationship between the seismic wave attenuation quality factor Q（ f ） and the frequency f for each component was calculated by using 1 069 Lg waveforms in the velocity window of 2.2—3.6 km/s. The results show that the Q₀ of vertical, west-east and north-south components are 237.1, 201.8 and 245.9, and the frequency exponent of the Q（ f ） are 0.44, 0.52 and 0.44, respectively. The result of this area is consistent with the results of the other seismically active regions in the world. Furthermore, in time domain the analysis of Q（ f ） suggests that the attenuation characteristics of crustal medium in this region do not change during the studied period, and the maximum response amplitude of 15 stations was not more than 6 in the region.