Erratum to: Earth, Planets and Space (2017) 69:21 DOI 10.1186/s40623-017-0611-9

Unfortunately, an important reference was missing in the original paper (Suito 2017). Therefore, it is necessary to add a reference. In addition, a sentence in the paper needs to be replaced as follows. It should be noted that all conclusions are not subject to correction.

Page 10, right column, Line 40

“The depth-dependent viscosity structure in this study contained the lowest viscosity at a depth of 150–300 km, which is consistent with these rock rheological estimates.” should be replaced as: “The depth-dependent viscosity structure in this study contained the lowest viscosity at a depth of 150–300 km, which is consistent with these rock rheological estimates. Recently published paper of Freed et al. (2017) regarding the postseismic deformation following the 2011 Tohoku-Oki earthquake also reported similar depth-dependent structure.”