Why do you think revolution swept so many african nations following their independence from european rule?

Revolution was a common occurrence because large vacuums of power usually followed what has been deemed "White Flight," or the emigration of Europeans out of Africa. During colonial periods, European government strove to maintain a small, strong, and central hold of power limited normally to white elites or native Africans who allied closely with those white elites. So when the European powers left Africa, many competing seats of power (traditionalists, military men, religious leaders) all sought to gain and maintain that central hold of power that had existed since the Berlin Conference in the late 1800s.