When a series of storms and twisters hit at least 10 states in the USA at the end of February, many victims used social media channels to report their status or those of neighbors and friends. That way they could indicate their exact location to family or search parties by just a single tweet or a facebook post. The app "Foursquare" for example allows users to "check in" to specific locations. Twitter's twittermap works similarly showing users' location on Google Maps. Facebook's Places page allow geotagging on Bing Maps. Georeferenced social media posts thus allow to analyze the effect of events as they happen. Maps based on social media tools proved to be useful not only in the American example. The Japanese government also used social media channels in the aftermath of the 2011 earthquake and tsunami, for example Google People Finder.
