Suito (2017) developed a three-dimensional viscoelastic model using Finite Element Method to understand the postseismic deformation that followed the 2011 Tohoku-Oki earthquake and to clarify which elements of the viscoelastic media affect the observed surface deformation. Of particular importance is the consideration of different viscosities between the mantle wedge and the oceanic mantle, and the inclusion of a thin weak layer beneath the slab, which has a dramatic impact on seafloor deformation. Far-field data as well as near-field data are also important for constraining the viscoelastic structure; the former is sensitive to viscoelastic relaxation at greater depths. Clearly, viscoelastic relaxation alone cannot explain the observed deformation. A combined viscoelastic and afterslip model is necessary for constructing a complete postseismic deformation model.