2019 will be the hundredth anniversary of a new start of international scientific collaborations after the First World War, in particular with the creation of the International Union of Geophysics and Geodesy, its associations, and national committees. It is a remarkable opportunity to celebrate the accomplishments of nonlinear geophysics during this past century, as well as to look forward to the challenges of the next century. It is also a remarkable opportunity to think about NPG's revival and testifies to its importance. NPG is therefore inviting the EGU Richardson medallists to contribute to this issue.

Please note that this special issue is only for invited contributions.