Slowly, then all at once
How complex systems fail: slowly, then all at once.
All complex sytems are full of non-linear. In a healthy complex system, these will have balancing feedback loops, holding each other in dynamic equilibrium. Given a small purturbence, these systems tend to fall back toward equilibrium, but a complex system is only ever . If the purturbation is too intense, the feedback loops that make it up will fly apart, resulting in a sudden failure.
Pace layers: different systems seem to boom and bust on different timelines. Failures at lower layers tend to create catastrophic discontinuities for those above.