They are gradual, but they need a spark. Then a single event might trigger a movement, releasing the energy that has accumulated over time, just like what happened in Egypt or certain other places.
Babu wani yunkuri na tarihi da ya faru haka kawai, a hankali a hankali ya bayyana; to sai dai kawai yana bukatar wani loakci da wani waje ne, wani lamari ya faru kwatsam sai wannan dama da karfi da ake da shi wanda kuma ya taru, sai ya bayyanar da kansa; sai ya zamanto kamar abin da ya faru a Masar da sauran wajaje.