A seismic surveying arrangement comprises a vertical source array (26) having at least two sources (27,28) of seismic energy. The source array (26) is disposed such that a first source (28) is located within a weathered layer (35) of the earth's interior and such that a second source (27) is located within the weathered layer at a greater depth than the first source or within a high velocity layer (8) underlying the weathered layer (35). The surveying arrangement also includes a first horizontal receiver array (29) located in the weathered layer, and means for processing seismic data acquired by the first receiver array. The processing means are able to process the acquired seismic data so as to attenuate seismic events involving reflection of seismic energy at at least one boundary face of the high velocity layer. The seismic surveying arrangement may also comprise a second receiver array (30) disposed at a lower depth than the first receiver array (29). Wavefield separation techniques may then be applied at both the receiver side and the source side.