起伏地表速度建模初步研究

Preliminary Study on Velocity Modeling for Irregular Surface

针对新疆山前带地形起伏、表层结构复杂以及横向变速剧烈的特点,采用初至波波形反演方法进行表层速度精细建模。模型试算结果表明,该方法能够较好地重建近地表速度模型的细节部分;时间域波形反演方法的实现效果较大程度地依赖初始模型。正演模拟证明,表层对地震波传播的影响很大,倾角较大且横向变速剧烈的模型,正演模拟的精度、横向分辨率以及照明效果都会受到表层的影响,并且最终影响了反演结果的精度和分辨率。

Aiming at the complex geological structures with the topographic relief, complex surface structures and strong velocity contrast in the mountain front area in Xinjiang, the first-arrival waveform inversion is adopted for detailed modeling of surface velocity. The results show that first-arrival waveform inversion can be used to reconstruct the fine details of the surface velocity model. Time-domain waveform inversion is somewhat sensitive to the initial model. The forward modeling indicates that seismic wave propagation is severely affected by the surface structure. The modeling precision, lateral resolution and illumination could be influenced by the irregular topography model with large dip and strong velocity contrast, hence leading to lower degrees of the modeling precision and resolution.