First, we consider a semilinear hyperbolic equation with partially known initial data in a bounded domain. For this system, we construct a locally distributed control that desensitizes a certain norm of the state. This result is new, and the method for proving it combines a judicious application of the Carleman estimate and a localization technique. Then we discuss possible extensions of our result. Finally, we apply our method to the exact controllability of two hyperbolic equations (one semilinear, and the other one linear) coupled in cascade through the boundary, the control acting in one equation only.