Why are these people there? An analysis based on Twitter

Social mining techniques enable gathering huge amount of data and allows inferring relevant information about Social Network Sites users such as social ties, interests, emotions, habits, etc. However, applying these techniques to tweets entail several difficulties consequence of their own characteristics: short messages written in informal language. In this paper we deal with this issues with the aim of finding out the reason why an unexpected group of people is in the same location at the same time. We show the results of applying our methodology in Madrid City during May Day.