Social media refer to internet based applications such as, for instance, social networks,
blogs, multimedia contentsharing sites and wikis.

Progressive use of Social Media in Emergencies
1st phase: Initially, when an emergency occurred, social media were used by
citizens:
- to communicate with their family and friends (need of connectivity);
- to search for further information (reduction of uncertainty).
2nd phase: Later, emergency responders started using social media, as an
additional communication channel, because information sharing and communication
are fundamental in emergency management.