Afterslip and Relaxation Processes

Left: afterslip. Right: Lower crust and upper mantle relaxation. Areas colored yellow either slip or flow after a large earthquake. Both the afterslip and relaxation processes occur deep under the faults (schematic red lines) that originally slipped in the earthquake. UC, Upper Crust; LC, Lower Crust; UM, Upper Mantle. The UC/LC boundary is schematically the brittle-ductile transition. Determining whether afterslip or relaxation occur after an earthquake is an active research area.