FK法合成地震动的频带范围研究

Research on bandwidth of ground motion simulated using FK approach

地震动合成方法的应用前景与其所能表达的有效频带范围紧密相关.本文研究基于频率波数域格林函数的地震动合成方法(FK法),分析频带范围的关键影响要素及处理措施.在介绍计算原理的基础上,概括FK法合成地震动的主要影响要素,分析地壳速度模型对子源地震矩、破裂时间和传播时间的影响.随后,分析格林函数传播宽频带地震波的能力,提出格林函数计算中的频带影响参数的建议值.为分析FK法的震源模型辐射宽频带地震波的能力,重点考察控制子源错动过程的震源时间函数和上升时间.研究认为,FK法具有合成宽频带地震动的能力,这需要采用合理的参数和模型.

The application prospect of ground motion simulation approach is closely related to the effective bandwidth of synthetics. Hence we studied the simulation approach based on the frequency-wavenumber Green’s function(FK approach),and analyzed the key factors affecting the bandwidth and the treatment measures. On the basis of the calculation principle introduction,we summarized the main factors influencing the ground motion simulated by FK approach,and analyzed the influences of the crustal velocity model on sub-source seismic moment,rupture time and propagation time. Then,we analyzed the ability of the Green’s function to propagate broadband seismic waves,and put forward the recommended values of parameters affecting bandwidth in the calculation of Green’s function. The source time function and the rise time controlling the sub-source slip process are investigated to analyze the ability of source model in FK approach to radiate broadband seismic waves. The results show that the FK approach has the ability to simulate broadband ground motion,and this requires reasonable parameters and models.