I am using QGIS 2.18 and I am trying to add symbols to my map but I cant find the kind of symbols I need. Is there a way I can get symbols depicting security threats, flooding, violence?
you could also try the QGIS Resource Sharing plugin, that's an easy way to get symbology resources. (http://qgis-contribution.github.io/QGIS-ResourceSharing)
QGIS Resource Sharing Plugin
Have you ever wished you can share QGIS resources easily with your peers? Well, this plugin might be handy for you!
This tools allows QGIS users to share resources (symbols, svgs, images, or processing scripts) in a repository so that other users can use it. Repository could be defined in remote GIT repositories (for now it supports Github and Bitbucket public repositories), local file system, or in http(s) with zip collections.
Find some symbols you like online in .svg format or make your own in Inkscape/Illustrator/Affinity Designer.
Then in QGIS go to Setting > Options > System and add the directory that the icons are in to the list of SVG Paths.
The icons will now appear in the list of SVGs for points when you change the Symbol layer type to SVG marker.