竖向地震动场的空间相干函数模型

根据台湾SMART 1台阵采集的六次重大地震的加速度数据记录,利用数字信号处理技术,对竖向地震动场的空间相干函数进行分析.按照各测点对在波传播方向上的投影距离进行分组,研究了竖向地震动场空间相干函数与它们的空间距离(投影距离)、频率的关系,发现它们随两点的距离增大而减小,且与这两点在地震波的传播方向上的投影距离有较大的关系,不具有“各向同性”的性质;它们均随频率的增大而减小.在总结前人研究成果的基础上,采用Hao提出的相干函数模型来描述竖向地震动场空间相干函数.根据实测地震数据,分别对相干函数理论表达式中的一些参数进行了拟合.结果表明,该模型具有较强的合理性和实用性.

SPACE COHERENCY FUNCTION MODEL OF VERTICAL GROUND MOTION

Based on six large earthquake records of acceleration collected in SMART 1 array in Taiwan, the space coherency functions of vertical seismic ground motion are discussed by means of signal process method. According to the distance projected on the direction of wave, stations are divided into groups which are named as pairs of station. The relation between vertical coherency function and space distance (projection distance) and the relation between vertical coherency function and frequency are studied. The larger the distance is, the smaller the coherency function is, especially for the projection distance. It is concluded that the coherency function is not isotropic. The higher the frequency is, the smaller the coherency function is. Hao抯 model of coherency function is used to describe the vertical space coherency function. The parameter values are estimated for each earthquake using least squares methods. It is demonstrated that this model is reasonable and adequate.