Efforts are being made to save and archive photographs, tweets, newsfeed, documents, oral interviews... There are a number of organizations doing this. I will list a few here, but check Harvard's page for more.
The Digital Archive of Japan's 2011 Disasters project is an initiative of the Edwin O. Reischauer Institute of Japanese Studies at Harvard University in collaboration with several partners. We aim to collect, preserve, and make accessible as much of the digital record of the disasters as possible, to enable scholarly research and analysis of the events and their effect.
The National Diet Library is harvesting web pages from local and regional governments as part of its Web Archiving Project. You must have Japanese (or use an internet-based translator) to read these archived pages.
By Virginia Tech on the Internet Archive. This collection depicts the events surrounding the 2011 Earthquake and Tsunami in Japan and the post-disaster reconstruction. Content includes blogs, social commentary, television/online news sites and aid organizations, with content in both English and Japanese.