Comparison of Power and Telecommunications Dependencies and Interdependencies in the 2011 Tohoku and 2010 Maule Earthquakes

This paper compares dependencies and interdependencies between power and telecommunication infrastructures during the 2011 MW 9.0 Tohoku earthquake in Japan with those in the 2010 MW 8.8 Maule offshore earthquake in Chile. This comparison is important to assess the extent to which particular failure modes and restoration processes are prevalent in two different cases, especially when quantification of infrastructure coupling is still in its infancy. These comparative observations are also relevant for the design and improvement of critical infrastructure and associated resilience. The analysis is conducted by comparing time series of power and telecommunication system damage, outages, and service restoration as field-collected in the regions affected by the respective earthquakes. The metrics used for the comparison, namely the dependence predominance and the restoration delay index, are based on cross-correlation functions and a measure of dependence predominance based on the peak cumulative cross-correlations and dominant restoration times between the two infrastructures. Results indicate that there is a strong coupling between the restoration of power and telecommunication infrastructure systems in both Japan and Chile events. For instance, the power system outage restoration process in Japan led the restoration of mobile communication networks more strongly than of that of landline telephony systems, confirming similar observations from the February 2010 earthquake in Chile, While in both Chile and Japan, the landline and mobile system restoration processes tended to occur together, likely due to infrastructure collocation in the switching centers and common transmission links. The trends from these two events provide evidence of the significant dependence of communication systems on power supply infrastructure, indicating the need for novel technological alternatives, such as microgrids, to improve communication networks' performance during disasters and set the foundation for future disaster-resilient smart grid systems.