Megathrust shear force controls mountain height at convergent plate margins

Abstract

The shear force along convergent plate boundary faults (megathrusts) determines the height of mountain ranges that can be mechanically sustained1–4. However, whether the true height of mountain ranges corresponds to this tectonically supported elevation is debated4–7. In particular, climate-dependent erosional processes are often assumed to exert a first-order control on mountain height5–12, although this assumption has remained difficult to validate12. Here we constrain the shear force along active megathrusts using their rheological properties and then determine the tectonically supported elevation using a force balance model. We show that the height of mountain ranges around the globe matches this elevation, irrespective of climatic conditions and the rate of erosion. This finding indicates that mountain ranges are close to force equilibrium and that their height is primarily controlled by the megathrust shear force. We conclude that temporal variations in mountain height reflect long-term changes in the force balance but are not indicative of a direct climate control on mountain elevation.