The Japan earthquake: the impact on traffic and routing observed by a local ISP

The Great East Japan Earthquake and Tsunami on March 11, 2011, disrupted a significant part of communications infrastructures both within the country and in connectivity to the rest of the world. Nonetheless, many users, especially in the Tokyo area, reported experiences that voice networks did not work yet the Internet did. At a macro level, the Internet was impressively resilient to the disaster, aside from the areas directly hit by the quake and ensuing tsunami. However, little is known about how the Internet was running during this period. We investigate the impact of the disaster to one major Japanese Internet Service Provider (ISP) by looking at measurements of traffic volumes and routing data from within the ISP, as well as routing data from an external neighbor ISP. Although we can clearly see circuit failures and subsequent repairs within the ISP, surprisingly little disruption was observed from outside.