Genes, N., Chary, M., and Chason, K. (2014). Analysis of Twitter Users' Sharing of Official New York Storm Response Messages. Medicine 2.0. 3(1):e1.
The authors evaluated official New York City tweets related to Superstorm Sandy (2012) and winter storm Nemo (2013) and how often they were re-tweeted. They found that information was shared beyond existing follower bases; official tweets during Sandy had lower lexical diversity, with links to more information, and were retweeted more than unofficial Sandy tweets; and NEMO-related tweets containing more general information were retweeted more often than those containing actionable information.