2012年5月28日唐山4.8级地震强地面运动模拟

Strong Ground Motions Simulation of Tangshan M4.8 Earthquake on May 28,2012

2012年5月28日唐山市古冶区与滦县交界发生4.8级地震。采用曲线网格三维有限差分方法模拟唐山4.8级地震波场传播过程,得到V_(X)分量在地表的快照图,总体呈圆形向外传播,能量分布比较均匀,符合点源地震的特征。将计算波形与不同台基的地震记录波形进行对比,发现计算波形和基岩区台站记录波形一致性较高,P波、S波初至位置、相位和最大振幅都能较好地对应,证明模拟结果的可靠性;计算波形与第四系覆盖区和过渡区的台站记录波形对比的结果较差,P波和S波初至位置基本对应,最大振幅和相位有较大偏差,计算波形在S波到达之后的能量衰减快于台站记录波形,这可能与模拟计算采用的速度结构模型中缺少第四系覆盖层的资料有关。

On May 28,2012,an M4.8 earthquake occurred at the border between Guye District and Luanxian County in Tangshan city.With the available three-dimensional velocity model and topography data,this paper applies curve grid finite difference method which considering the terrain effect to the earthquake simulation of ground motion,get a few of snapshots of the image speed V_(X).It can be seen that the earthquake spread outward in the form of approximate circular,energy of the earthquake is uniformly distributed,that is in accordance with point-source seismic characteristics.By comparing calculated waveform with station recorded waveform,it is found that the calculated waveform and the bedrock area stations recorded waveform can be well compared,the beginning of P wave and S wave,phase and maximum amplitude of 4.8 earthquake waveform have good consistency,which proves the validity of the simulation results.The result of calculated waveform comparing with the recorded waveform which stations on the Quaternary strata coverage area and the transition region is not well,the beginning of P wave and S wave can correspond,but maximum amplitude and phase have larger deviation.After the arrival of S waves,the energy attenuation of the calculated wave is faster than that of stations recorded waveform,which may be caused by lack of Quaternary thickness data in P wave velocity structure model of the simulation calculation.