1. A method for characterising the evolution of a subsurface volume, said method comprising: providing a first survey of the subsurface volume with a first set of seismic traces corresponding to a first time; providing a second survey of the subsurface volume with a second set of seismic traces corresponding to a second time; constructing an analytic filter operable to shift at least one seismic trace in dependence of a model parameter; and performing an inversion to obtain estimates for said model parameter such that said analytic filter aligns said first survey and said second survey.