Human society is a complex system composed of subsidiary complex systems.
Let us take a modern city as an example.
The physical infrastructure consists of the following complex systems:
Electrical Power Generation and Distribution (dependent on transportation of fuel)
Potable Water collection, treatment, and distribution
Sewage collection and treatment
Business and Home Environmental Controls
Roads (dependent on fuel supplies and subject to degradation on loss of Electrical Power)
Rail Roads (dependent on fuel supplies and Electrical Power for control and switching)
Air Transport (dependent on fuel supplies and Electrical Power)
POL (dependent upon supply of Crude Oil, Transportation, and Electrical Power)
Gasoline (requires electrical power to distill from Crude Oil)
Jet Fuel (requires electrical power to distill from Crude Oil)
Diesel Fuel (requires electrical power to distill from Crude Oil)
Natural Gas (dependent on Electrical Power for control of delivery)
From these obvious relationships we can easily discern that disruption of one or more subsystem will have cascading effects on the rest of the systems.
Efficiency in the use of resources drives centralization. One large power plant is more efficient than multiple smaller power plants. However, should that one power plant be disrupted, a cascade of effects will be felt on other critical infrastructure across a larger swath of population.
Survivability drives design towards smaller less efficient nodes which offer each other mutual support but which can sustain the temporary (or not so temporary) loss of one or more nodes.
When a whole state (we’re talking about you, California), region (hello, Northeast), or Country suffers a cascading failure (or rolling blackouts) it’s a clear indication that “efficiency” was optimized at the expense of survivability.
Earthquakes, Tsunami, and other natural disasters are facts of life here on planet Earth. Failing to design our infrastructure to survive such disasters through redundancy (smaller nodes) and geographical separation is a choice not to survive as a society.
Mega cities with efficient centralized infrastructure are societal suicide pacts.
Hat Tip to VDH for the inspiration.