Although the relationship between public policies and disaster risk is apparent, its nature is not so evident. The dominant model, the disaster management cycle, is based on the principle of response and return to normalcy. In addition, it is accepted that policies are based on constant legal development and that risk governance is responsive to successive disasters. The temporal pattern of large nature-triggered and technological disaster events in Japan since the end of WWII has been researched by measuring the duration of events and discontinuities between them as well as the development of the regulation of disaster risk. The evolutionary relationship between these two parameters and other political and economic factors was reconstructed through the notion of disaster timescape.
The results do not support the notion of disaster cycle, nor a return to normalcy at the national scale, but a timescape of overlapping and successive events. Furthermore, there is no evidence of a clear association between major events and legal development on disaster risk, neither between this and economic or political crises. Nor is there continual evolution of regulation of disaster risk but, rather, a sequence of long periods of quiescence and acceleration more indicative of policy punctuation. The disaster timescape points to greater complexity with the interaction of multiple driving forces and an unstable balance that goes beyond a simple linear cause and effect. In the disaster timescape, there appear to be overlapping trajectories of environmental, social, political and economic processes.