海底水平层状黏弹介质地震波有限差分正演模拟

Seismic wave finite difference forward modeling in horizontal layered viscoelastic medium of sea floor

地震波在海底地层的传播,有必要考虑到介质对地震波发挥的衰减和频散效应.这些效应通常可以通过品质因子Q来量化.论文讨论了水平层状黏弹介质内平面波的数值模拟,采用了一种计算垂向黏弹性介质里的平面波响应的FDTD有效算法,用来估算存在垂向速度变化模型的平面波传播参数响应值.将视品质因子Q和视速度与实测的数值对比,证实了该算法在黏弹性模拟中的精确性,证明了在10~40 Hz的相关频率范围内,即使是强衰减介质,该算法也能取得良好的计算结果.在此基础上,应用这种算法求解海底水平层状介质模型,得到了海底黏弹介质的一维地震波场响应,取得了理想效果.

It is necessary to take into account the attenuation and dispersion effect of the medium on the seismic wave. These effects can usually be quantified by quality factor Q. The numerical simulation of plane wave in horizontal layered viscoelastic medium is discussed,we adopt a FDTD algorithm effectively to calculate the vertical plane wave response in the viscoelastic media,and estimate the response values of the plane wave propagation parameters models with the vertical speed changing. Then,We compare the quality factor Q and apparent velocity with the measured values. It proves that the algorithm for viscoelastic simulation is precise,and it can also get good results in the frequency range of 10 ~ 40 Hz,even in a strong attenuation medium. In addition,We apply this algorithm to solve underwater horizontal layered medium model,and get ideal effect of one dimensional seismic wave field response of the viscoelastic medium.