SUMMARY

To allow the implementation of the elastic reverse-time migration algorithm for marine datasets it is necessary to convert the recorded pressure field into a vector displacement field. Although the two wavefields are related by a very simple equation (the displacement field is proportional to the gradient of the pressure field), it is not possible in practice to directly apply this equation to most real cases. The vertical component of the gradient cannot be directly computed in the space domain because the typical marine geometry comprises a single horizontal line of receivers. However, with very few assumptions it is possible to separate the upcoming and downgoing components of the wavefield and obtain an operator in the frequency-horizontal wavenumber domain that can effectively compute the pressure gradient. Results with synthetic and real data demonstrate the applicability of the method.