Vertical displacements at convergent plate margins

Observations show that vertical displacements of the Earth's surface near convergent plate margins may reach magnitudes on the order of hundreds of metres to some kilometres. These displacements may be caused by various processes which are related to plate convergence, for example, variations in surface plate velocities and buoyancy of the subducting lithosphere.

We have quantified vertical surface displacements at convergent plate margins resulting from imposed variations on the subduction process. To this purpose we use a two-dimensional mechanical model (TECTON). First a model is defined in which the subducting plate is driven by its negative buoyancy and a velocity at its surface side boundary. Its equilibrium topography (after around 2 Myr, see figure) is the reference level for examination of surface displacements resulting from variations in slab buoyancy, velocity of the surface plates, friction along the interplate contact and subduction zone roll-back.

We find that vertical surface displacements induced by changes in a subduction zone system can reach a magnitude of a few (around 2-4) kilometres on the margins of both the overriding and the subducting plate.


subduction model of susanne


The figure shows the input model above, the subduction velocity is 4 cm/yr. Below are the results after 2 Myr. Red curve on top is the velocity measured along the surface, the green curve in the middle is the surface displacement.