Contagious Diffusion of Political Violence
https://www.tandfonline.com/doi/full/10.1080/1057610X.2017.1290428
This article drew method from spatial diffusion of crime to investigate spread of terrorism across national borders from 1970-2013. The researchers defined contagious diffusion of terrorism as expand of terrorism from a host country to an adjoining country. They used Global Terrorism Database through Spatial Autocorrelation statistics analysis to uncover spatial and chronical terrorism attack patterns and contrast contagious and non-contagious terrorism activities. Despite prominent examples of contagious spread of terrorism in Middle East, South Asia, North Africa and Sub-Saharan Africa, the overall contagion is rare compared to non-contagious spread.
The researchers rationalized their findings based on the fact that there are more limitations on contagious increases in terrorism than non-contagious one. Especially with the rise of global social media, it is even more likely for terrorism organizations to recruit foreign fighters with online propaganda than direct border conflicts, as examples from ISIS. However, as the researcher admitted themselves, their definition of contagious diffusion of terrorism might be too conservative to give an up-to-date view. It is hard to distinguish non-contagious diffusion instances across neighbors and to identify terrorism from the same organization or a cohesive movement across ideological backgrounds, later of which is more concerning.
The spread of terrorism to some extent resembles the pattern of contagious diseases. The frequent exchange of population between bordering countries provides an environment more vulnerable to spread of terrorism with their similar social and political context. The ability to spread farther would decrease as the probability to incline toward terrorism becomes less likely without a similarly violent political context. Even with the non-contagious spread of terrorism through social media, defined by the researchers, forms a online social network of nodes representing terrorist and potential recruits.