SELEN4 SealEveL EquatioN solver - version 4 This repository contains SELEN, an open-source Fortran code for the numerical solution of the Sea Level Equation (SLE) for a spherical, layered, rotating Eartch with viscoelastic rheology. SELEN implements a gravitationally and topographically self-consistent SLE and can compute several quantities of interest for the Glacial Isostatic Adjustment (GIA) problem, including Relative Sea-Level (RSL) curves, present-day sealevel rates at tide gauges, surface deformations and perturbations of the gravity field, geodetic fingerprints and paleo-topography maps. SELEN includes portions of the SHTOOLS library by Mark A. Wieczorek and Matthias Meschede and surboutines from Max Tegmark for the icosahedron-shaped pixelization of the sphere. SELEN is distributed under the 3-clause BSD license.