Thank you Tyler Cowen:
Has anyone linked to the DiPasquale and Glaeser 1996 paper on riots yet?
We examine the causes of rioting using international data, evidence from the race riots in the 1960s in the U.S., and Census data from Los Angeles, 1990. We find some support for the notions that the opportunity cost of time and the potential costs of punishment influence the incidence and intensity of riots. Beyond these individual costs and benefits, community structure matters. In our results, ethnic diversity seems a significant determinant of rioting, while we find little evidence that poverty in the community matters.
Here is a well-known political science paper on economic conditions and riots in India. Here is an economics paper on riots in India, AER 2008. Here is Alex’s piece on riots (gated). In London, the riots are getting closer to the LSE.