  The rise of social media platforms provides an unbounded, infinitely rich
source of aggregate knowledge of the world around us, both historic and
real-time, from a human perspective. The greatest challenge we face is how to
process and understand this raw and unstructured data, go beyond individual
observations and see the "big picture"--the domain of Situation Awareness. We
provide an extensive survey of Artificial Intelligence research, focusing on
microblog social media data with applications to Situation Awareness, that
gives the seminal work and state-of-the-art approaches across six thematic
areas: Crime, Disasters, Finance, Physical Environment, Politics, and Health
and Population. We provide a novel, unified methodological perspective,
identify key results and challenges, and present ongoing research directions.
