Evidence for eastward mantle flow beneath the Caribbean plate from numerical modeling

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Ana M. Negredo, Ivone Jimenez-Munt and Antonio Villaseñor

We have applied a thin-shell modeling technique to study the neotectonics of the Caribbean plate. Kinematic conditions computed assuming rotation poles and velocities from NUVEL-1A and from recent geodetic studies have been applied at the lateral boundaries of the model to represent the motion of the adjacent plates with respect to the Caribbean. We have generated a large number of models varying the values of the fault friction coefficient and shear traction on the base of the plate exerted by lower mantle flow. The quality of the models has been evaluated by comparing their predictions with data on seismic strain rate, stress direction, geodetic baseline changes, and slip rates. Our results indicate that the only successful models are those with low values of fault friction coefficient and significant basal shear traction exerted by eastward lower mantle flow beneath the Caribbean.

Strain rate distribution and horizontal velocity pattern in the interior of the Caribbean plate (arrows) predicted by a successful model with fault friction coefficient of 0.03 and mantle velocity at 400 km depth of 20 mm/yr.