干旱区生态环境知识资源中心

Ground roll is a significant source of noise in land seismic data, with crossline scattered ground roll particularly difficult to suppress. This noise arises from surface heterogeneities lateral to the receiver spread, and in desert regions sand dunes are a major contributor. However, the nature of this noise is poorly understood, preventing the design of more effective data acquisition or processing techniques. Here we present numerical simulations demonstrating that a barchan sand dune acts as a resonator, absorbing energy from ground roll and reemitting it over an extensive period of time. We derive and validate a mathematical framework that quantitatively describes the properties of the emitted waves and demonstrate that wave amplitude is estimable from easily measurable bulk properties of the dune. Having identified regions in time, space, and frequency space at which noise will be more significant, we propose reducing dune-scattered noise through careful survey design and data processing. In particular, we predict that seismic noise will be lower upwind of barchan dunes, and at frequencies far from a resonant frequency 2c(S)/H, for dune height H and typical seismic velocity within the dune c(S). This work is especially relevant to seismic acquisition in the vicinity of a dune field, where scattered noise appears incoherent and difficulties arise with alternative approaches to noise suppression.