An upwind finite-diff erence scheme of eikonal equation along exp anding wavefronts is developed which can ca lculate imaging condition of reverse-time migration.

• 采用逆时格式差分求解程函方程,得到网格空间中各点的直达波旅行时,以此作为弹性波逆时偏移的成像条件,实现了二维多波多分量资料的叠前逆时深度偏移。