Ambient noise interferometry

Seismic interferometry is a technique that reconstructs the Green’s function (the impulse response of the ground) between two receivers by cross-correlating ambient seismic noise or scattered waves, effectively turning one receiver into a virtual source. This method leverages the continuous background vibrations in the Earth — originating from ocean microseisms, atmospheric disturbances, or anthropogenic sources — to retrieve coherent surface wave signals without the need for active sources. When applied across dense nodal arrays, the extracted surface wave dispersion curves from multiple station pairs can be inverted using ambient noise surface wave tomography (ANSWT) to produce 2D or 3D shear-wave velocity models of the shallow crust. This approach is particularly well-suited for imaging complex near-surface structures as it provides high-resolution velocity information at depths ranging from a few tens to several hundreds of meters, depending on the frequency content of the ambient wavefield.

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