A method for preventing catastrophic damage in a drivetrain of a wind turbine includes receiving, via a controller, a speed measurement of the generator of the drivetrain. The method also includes determining an electrical torque of a generator of the drivetrain of the wind turbine. The method further includes estimating, via the controller, a mechanical torque of the rotor as a function of at least one of the electrical torque and the speed measurement of the generator. Further, the method includes comparing, via the controller, the estimated mechanical torque to an implausible torque threshold, wherein torque values above the implausible torque threshold speed values greater that the implausible speed threshold. Moreover, the method includes implementing, via the controller, a control action for the wind turbine when the estimated mechanical torque exceeds the implausible torque threshold.