全火星模型中震波传播特征的数值模拟研究

Numerical Modeling of Global Seismic Wave Propagation in the Whole Mars Models

采用基于交错网格的傅里叶伪谱与有限差分混合方法,求解弹性波动方程,根据地球化学分析得到的两个火星理论结构模型,模拟二维全火星模型中P-SV波和SH波的传播过程。根据理论地震图和波场快照,讨论全火星模型中震波的传播过程以及各种震相的产生和演变,分析模型内部火星壳厚度以及火星核幔边界深度对震波传播的影响。结果表明,在低速火星壳内部多重反射波及转换波的相干叠加会形成很强的波列,其特征受火星壳厚度的影响较大,在切向分量上可以更清晰地观测到核幔边界的反射震相。

The pseudospectral and finite difference hybrid method on staggered grid is applied to solve seismic wave equations for two Martian structure models derived from geochemical analysis.The numerical modeling is used to calculate P-SV and SH wave propagation inside 2-D whole Mars models.The generation and propagation of various seismic phases in the whole Mars models are shown by synthetic seismograms and wavefield snapshots.Effect of Martian crustal thickness and the depth of Martian core-mantle boundary on seismic wave propagation is analyzed with synthetic seismograms.Multiple reflections and conversions of seismic waves and their constructive interference inside the low-velocity Martian crust form reverberating wave trains,which are strongly affected by the thickness of Martian crust.Seismic reflections from core-mantle boundary can be clearly identified from the calculated transverse component seismogram.