临河盆地中部地区地震动高频衰减参数kappa值的研究

kappa值是描述地震动傅里叶幅值谱高频段衰减速率的物理量，其是地震动模拟中的一个重要参数。该研究以临河盆地中部地区为研究区域(N:40°—42°;E:106°—108°),选取2009-2019年盆地内4个强震动台站记录到的16次地震(2≤M_S≤6)26条强震数据，利用Anderson与Hough提出的经典算法(傅氏谱法),将加速度记录的水平方向的分量kappa(E-W)与kappa(N-S)分别研究。利用kappa值的均值(kappa(Mean))与震中距的拟合，发现其存在较为明显的线性关系，估算出临河盆地中部地区的高频衰减参数kappa0值为0.044～0.050 s。利用线性关系斜率k_R,估算临河盆地中部地区180 km范围内的等效品质因子Q值为2 763～3 367。四个台站的kappa值与震中距分布关系与Castro研究意大利翁布里亚盆地kappa值分布关系一致，存在70至100 km内kappa值有慢增长趋势，此结论验证了我们估算的合理性。

Study on kappa value of high frequency attenuation parameter of ground motion in central Linhe Basin

Kappa value is a physical quantity that describes the attenuation rate of ground motion Fourier amplitude spectrum in high frequency band, which is an important parameter needed in ground motion simulation. In this study, the central area of Linhe Basin was taken as the study area(N:40°—42°; E:106°—108°), 26 strong earthquake data of 16earthquakes(2≤M_S≤6 recorded by 4 strong motion stations in the basin from 2009 to 2019 were selected, and the classical algorithm(Fourier spectrum method)proposed by Anderson and Hough was used. The horizontal components kappa(E-W)and kappa(N-S)of acceleration records were studied separately. By fitting the average kappa value(kappa(Mean))with the distance from the epicenter, it is found that there is an obvious linear relationship, and the kappa value of the high frequency attenuation parameter in the central area of Linhe Basin is estimated to be 0.044-0.050s. Using the slope of linear relation k_R, the equivalent quality factor Q value within 180 km of the central area of Linhe Basin was estimated to be 2763-3367.The kappa values of the four stations are consistent with the distribution relationship between the distance to the epicenter and the kappa value distribution relationship of Castro in the Umbria Basin, Italy. There is a slow increasing trend of Kappa value within 70 to 100 kilometers, which verifies the rationality of our estimation.