turned out to be a 20-foot geyser gushing from a manhole. Twitter and Facebook proved important sources of information on other problems such as the flooding of some San Francisco Municipal Railway (Muni) stations. Such reports can complement information provided by officials on the scene, who may not be able to provide reports because they are overburdened with responding to events.

Another lesson learned from the San Francisco flash flood incident is that people on the ground may be the source of both the first reports and the most detailed reports (including pictures and video)—and can make such information widely available to the public using social media. On the one hand, there are potentially significant benefits to people’s receiving such prompt and detailed information. On the other hand, there are risks that false information will be reported and spread. The net result is that social media communiqués on such incidents can both aid and complicate the task of emergency managers.


Users of Twitter during crises are re-posting information from traditional media, providing commentary on the event and on the public and government response, and informing their connections as to how they are themselves being affected by the event. A 2009 study of Twitter content during a crisis found that message content could be categorized as follows: 37 percent of the messages provided information (warnings, updates, answers); 34 percent were commentary; 26 percent dealt with personal impact or requests for information; and 4 percent were promotions of available media coverage or products and services.1 In addition to individuals sending messages, public officials can also make use of Twitter to reach portions of the public. Indeed, a recent study suggests that brief messages can be communicated during disasters in a highly effective manner.2

The demographics of Twitter usage differ from those for mobile phones, with a penetration rate significantly lower than the 85 percent who subscribe to cellular telephone service. Also, Twitter users tend to be younger and richer, and more of them are in nonminority populations. According to data collected in March 2010, the majority of Twitter users


F. Vultee and D.M. Vultee. “What We Tweet About When We Tweet About Disasters: The Nature and Sources of Microblog Comments During Emergencies.” Paper presented at the 93rd National Communication Association Annual Convention, Chicago, Ill., November 12-15, 2009.


S.R. Veil, T. Buehner, and M. Palenchar. “Increasing Dialogue in Disasters: Incorporating Social Media in Risk and Crisis Communication.” Paper presented at the National Communication Association Conference, San Francisco, Calif., November 2010.

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