K. Bertrand, Y. Bar-Yam, Contagion and cascades through the Middle East: Tunisia, Egypt, Jordan, Syria..., NECSI Technical Report 2011-2-01 (2/1/2011).
February 1, 2011 - There can be little doubt that the revolution in Tunisia has been the spark for revolts across the Middle East. Egypt in particular has experienced a popular uprising in the wake of the Tunisian overthrow, with Yemen, Algeria, and Jordan also seeing civilian protests. The unrest in Egypt threatens to destabilize the region further, as Egypt occupies a much more prominent role than Tunisia due to its greater size and geopolitical placement.
Besides the countries already experiencing such turmoil, Syria, Pakistan, and Libya have been cited as countries with the potential to stage uprisings. These countries are all well-placed for a spatial spread, as well as linked to the existing unrest by religion and ethnicity. However, some suggest that China may be influenced by the Middle East uprisings as well. Authorities in China seem to fear the same; the Chinese word for "Egypt" has been blacklisted on the country's Internet searches.
How and why is the unrest spreading? Is there a "domino effect"?
One possibility is a contagion model, akin to the spread of panic in a crowded theater. States, or perhaps individual people, choose to protest or not based on their neighbors' actions and success rate. By this mechanism, we might expect the states that are currently in turmoil to reinforce one another, and that the more states there are experiencing protest, the more likely another state is to rise up as well.
Another suggestion is to consider the entire Middle East region to be a system in a state of self-organized criticality.
A self-organized critical system is defined as a complex system which-without explicit design or deliberate external shaping-trends towards a critical state. This critical state is unstable and subject to cascades of varying sizes into less organized states.
The archetypal example is a sandpile slowly growing by additional sand dropped onto the pile, grain by grain. A single grain dropped on the pile can occasionally cause an "avalanche" of unpredictable size. The initial grain can cause other grains to fall, which in turn can effect still more. The avalanches display power-law behavior: small ones happen much, much more frequently than large ones.
The basis for the cascade is an underlying buildup of tensions (like the sand) which has to reach a point of crisis at any one location before actions are taken. However, this point of crisis also depends on the actions of neighbors. Thus, once something happens in one place, the outbreak cascades. The current unrest can thus be considered as an avalanche in the sandpile of the Middle East. Tensions in the region have built up to a critical state, and the uprising in Tunisia acted as the grain which began the cascade.
Cite as: K. Bertrand, Y. Bar-Yam, Contagion and cascades through the Middle East: Tunisia, Egypt, Jordan, Syria..., NECSI Technical Report 2011-2-01 (2/1/2011).
 Egypt's revolt: Which country is the next 'domino'?, The Week (1/31/2011)
 G. C. Chang, Egypt is the next Tunisia. What is the next Egypt?, Forbes (1/30/2011).
 BBC online live coverage of Egypt unrest (1/31/11, 16:23).
 Per Bak, How Nature Works (Copernicus, New York, 1996).