Sheared flow layers driven by the magnetic energy released in reconnection processes are studied with the magneto-hydrodynamics (MHD) and proposed as a triggering mechanism for internal transport barrier (ITB) in tokamak plasmas. The double tearing mode mediated by anomalous electron viscosity is investigated as en example in configurations with non-monotonic safety
factor profiles. The quasi-linear development of the mode is simulated and the emphasis is placed on the formation of sheared poloidal flow layers in the vicinity of the magnetic islands. For the double viscosity tearing modes, it is shown that the sheared flows induced by the mode may reach the level required by the condition for ITB formation.
In addition, the flow layers are found to form just outside the magnetic islands. This resembles the experimental observations on JET that two radially separated ITBs simultaneously exist and follow the two q=2 surfaces in a section of JET discharge pulse 51573 and that the ITBs are terminated by an m=2 MHD mode which extends from the inner to the outer foot point location of the two ITBs.
Possible explanation for the experimental observations that the preferential formation of transport barriers in the proximity of
low order rational surfaces is discussed.

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