Personally, I don't like the word viral for this infographic… I like the word shareable. Many times you can exceed expectations on each key element within this infographic – but it doesn't mean that it's going viral.
Leo Widrich over on the Buffer Blog wrote a great post about what makes content spread. In it, he analyzes some of the elements that helped one particular blog post get over half a million likes. He also references an interesting research paper about what makes online content go viral.