The discovery of Episodic Tremor and Slip (ETS) has a surprising benefit: it may help geologists improve assessments of damage that could be caused by the next great subduction zone earthquake. Locating the area where ETS occurs between the plates helps to define the eastern boundary of the locked zone that will snap apart in the next great earthquake. Understanding the location and extent of the locked zone will help geologists predict where the most intense shaking will occur and how intense it will be.