Nations with nuclear power programmes are, or intend to, become engaged in planning to dispose of their higher-level and/or longer-lived radioactive waste in deep geologic repositories. If they remain undisturbed, geologic repositories can isolate these materials from the biosphere for extremely long times. To ensure that future generations are aware of these repositories, one element of the communication strategy could be the use of long-lasting markers and/or monuments placed in the vicinity of closed repositories. In order to develop an understanding of the potential effectiveness of markers – on their own – as a medium to convey information and warnings to future generations, this paper examines the role of Japanese stone markers in informing current generations for protecting themselves against the potential devastation of tsunamis.