The response of linear dynamic structures can be decomposed into modal components, where each natural frequency is also represented by a corresponding mode shape and damping ratio. While vibration-fatigue-damage identification was recently expanded using modal decomposition, this research proposes a modal-decomposition-based thermoelastic damage identification method. With the proposed method, a thermal camera can be used to identify the damage intensity of a particular mode shape. The proposed method is presented using a randomly excited structure exposed to multiaxial loads. With this, the intensity of a particular fatigue source is clearly related to the underlying structural dynamics.