震级大小和传播距离对相干函数的影响

Influence of magnitude and propagation distance on coherency function

根据我国台湾SMART-1台阵采集的3次不同震级和震源距的地震加速度记录,分别计算了台站间距d等于200、400、800、1000和2000m的相干系数,并采用LOH和Abrahamson提出的相干函数模型对相干系数进行了拟合,对比结果表明:(1)震级大小对地震动相干性影响较大,震级小的相干性较好;(2)地震波的传播距离对地震动的相干性影响不显著,震源距较小地震的地震动相干性较小。并针对地震动相干函数中的只包含台站间距和频率2个参数的情况,建议在今后的研究中,相干函数表达式应该尽可能考虑地震震级和传播距离的影响。

Based on three earthquake records of accelerations with different earthquake magnitudes and hypocentral distance collected in SMART-1 array in Taiwan of our country, the coherency modulus of station spacing d at 200m, 400m, 800m, 1000m and 2000m are respectively calculated, and fitted using the coherence function model proposed by LOH and Abrahamson. The results show that (1) earthquake magnitude has a great influence on the coherence of earthquakes and the smaller the magnitude, the better coherence;(2) the influence of seismic wave propagation distance on the coherence of ground motion is insignificant, and the smaller the focal distance is, the smaller the coherence will be. The paper suggests that the influence of earthquake magnitude and propagation distance should be considered in coherency function expression as far as possible in future studies.