Bending stresses in subducted lithosphere

Summary. The flow of the mantle near subducted lithosphere applies a force (dynamic load) to the slab which has a normal component as well as a shear component. In addition, the greater density of the slab compared to the surrounding mantle results in a downward force (negative buoyancy) which also has a component normal to the slab. Because the slab is long compared to its thickness, the stresses in the slab due to the normal components of the loads are accurately estimated from the bending moment. We have used previous estimates of the loads to compute the bending moment in the slab as a function of distance down the slab. Our results indicate that the loads applied to the slab are large compared to its strength; bending moments due to normal loads will not be transmitted over the length of the slab. Instead, the slab will deflect so that the normal loads are balanced locally.