云南地区非弹性衰减系数及场地响应研究

利用2011～2015年云南区域地震台网的数字波形资料，选取互相衔接的3段几何衰减模型，运用基于遗传算法的Atkinson方法反演云南地区的介质品质因子Q(f)，得到云南地区Q值与频率的关系为Q(f)=193.8f0.528。采用Brune的ω平方模型约束震源位移谱，使用Moya方法联合多台多地震数据计算得到46个台站的场地响应。结果显示，岩石台基对地震波信号在不同频段的放大作用并不相同，云南地区场地响应总体存在明显的低频放大、高频衰减现象，在卓越频段1～4 Hz场地放大倍数大多在1～10倍，而在高频段（10 Hz以上）场地的衰减大多在0.05~1倍。

Study of Non-Elasticity Attenuation and Site Response in Yunnan

Using digital waveform data recorded by regional seismic networks in Yunnan between 2011 and 2015, attenuation characteristics and site response respectively are calculated. The frequency dependent Q(f) is obtained by the iterative grid-search technique, as described by Atkinson and Mereu, based on trilinear geometrical spreading model. Our results demonstrate that for Yunnan the associated model for regional quality factor for frequencies can be expressed as Q(f)=193.8f0.528. Additionally, we ascertain the source spectra determined by the model of Brune and the site responses of seismic stations derived by Moya’s method using genetic algorithms. The site response results of 46 stations demonstrate that the seismic signal amplification of Station bedrock is not the same in different frequency bands. The site response in Yunnan region shows obvious amplification with low frequency and attenuation with high frequency. Site amplifications are apparent in excellent frequency band (1~4 Hz), mostly between 1 and 10 times, and in the high frequency (10 Hz or more) site attenuation is mostly between 0.05 and 1 times.