"I apologize to Giorgio Chiellini and the entire football family." : zur Rolle Sozialer Medien in der Krisenkommunikation - dargestellt an Beispielen im Kontext der Fußball-WM 2014 in Brasilien = "I apologize to Giorgio Chiellini and the entire football family." : a discussion of the role of social media in crisis communication based on examples from the 2014 World Cup Brazil