Finite Element Stress Modelling for Subducting Lithosphere under Varying Angle of Inclination

We, in the present study, examine the stress regime in a subducting oceanic lithosphere using 2D finite element modelling under plain strain condition. The model parameters along with the rheological parameters of different layers are systematically used for the modelling. Velocity of the plate and mantle are explained either by the displacement or force acting on the boundary of the model. The bottom boundary of the model is rigidly fixed in the vertical direction and the right boundary is fixed in the horizontal direction. Density contrast is applied in the lithospheric mantle to simulate the slab pull force. We analyze the variation in the first principal stress with the dip angle (i.e. 30°, 45° and 60°) of the descending lithosphere. It is noted that the zones of compression keep on increasing with decrease in subducting angle. For 60° inclination, the compressive stress ( 1) is mainly concentrated at depth greater than 200 km right within the descending lithosphere. As the angle of inclination is decreased, the compressive zone is extended towards the shallower part of the lithosphere, and the zone of compression spreads out more in the mantle with further decrease of inclination.