The waves reflect different kinds of rocks under the surface. Hard or dense rocks reflect more strongly than soft or porous ones; and the time lag of waves can indicate the depth of the reflecting layer.

• 振动波反映出地下不同种类的岩石。硬岩(致密岩)的反射波比软岩(多孔岩)的反射波强。振动波的时间滞差还可指明反射层的深度。