No. Google Insights clearly shows that although Facebook is getting more and more popular in Japan, the earthquake almost had no impact (at least in the short run) on its growth. On the other hand, Twitter and UStream saw a sharp traffic spike right after the quake.
Furthermore, when the quake hit, about 98% of the population in the Tohoku area was not on Facebook while even some of the local governments were using Twitter. Many people reported as saved by Twitter; there’s no evidence that someone was saved after the quake because he/she found help on Facebook. https://adamacar.wordpress.com/2011/03/18/last-tweet-before-the-tsunami-hit/
More on the Japanese social media scene http://asiajin.com/blog/2012/04/02/a-summary-of-the-latest-studies-about-japan-social-media/