Of societal collapses or social break downs. People can pretend this history does not exist and that it's financial wealth makes it a healthy and stable region. If you go far back in history you find huge massacres, riots, and the completely uncaring destruction of people's lives. If you feel safe by what the police report is telling you then you need to understand the situation and who is really on your side now. How far will people go for a good slice of the pie. The Bay certainly is no semi socialist paradise. Take care, be aware, and beware.