Great east Japan earthquake viewed from a URL shortener

On March 11th 2011, a great earthquake and tsunami hit eastern Japan. After that, several web sites, especially those providing helpful disaster-related information, were overloaded due to flash crowds caused by Twitter users. In order to mitigate the flash crowds, we develop a new URL shortener that redirects Twitter users to a CDN instead of original sites, since Twitter users rely on URL shorteners like bit.ly to shorten long URLs. In this paper, we describe our experience of developing and operating the URL shortener in the aftermath of the giant earthquake. Since the flash crowds were a serious problem in an emergency, we had to develop it as quickly as possible with a spirit of so-called agile software development. We then explain our HTTP request log collected at the URL shortener (it is now available online). To investigate the cause of flash crowds, the log is examined with tweets (Twitter messages) provided by another research project; this collaboration is realized by the encouragement of the workshop committee. We hope our experience will be helpful in tackling future disasters.