Numerical models of subduction zones: Causes and dynamics of the trench roll back effect with application to the Mediterranean and other subduction zones

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Subduction zones are not stationary, many of them show a pronounced trench migration, sometimes also called "roll back" (e g the Mediterranean or the Tonga subduction zones). While these migration rates have been quantified to a good resolution in recent years, the underlying physics of this process is only poorly understood. A set of controlling mechanisms or parameters is proposed including the mobility of nearby continents embedded in the subducting plate, mantledrag, resistance within the transition zone, rheological coupling to the overriding plate, and rheological slab properties among others. Fluid dynamical numerical models will be carried, in which the flow-, energy-, and rheological equations will be solved to study the self-consistent evolution ob subduction and trench migration. It will be tried to identify the dynamic characteristics of the different mechanisms and to relate dynamical, rheological, and configurational parameters of different cases to trench migration rates. It will then be tried to relate the different mechanisms and migration rates to observable quantities, such as stresses within the slap and in the overriding region, topography. uplift rates, gravity, and others. A data base of subduction and trench migration parameters will be built and compard to the model results. Particular emphasis will be put on the "roll back effects" of the Mediterranean and the Tonga subduction zones.