The Line of Death (LOD), is very close to the actual standard of living, due to poverty, famine, poor housing etc. If you are extremely close, then buildings collapse under their own weight! The amount of time spent under this line may determine the total dead, ie. a slow recovery brings disease, etc.
A rich city has more margin about the LOD. They can take a hit without massive loss of life.
However, they may have a line where there is severe economic disruption, and a significant crash in the standard of living. This is due to power outages in winter, roads, bridges, etc. If you hit that point, a lot of money flies out the window!
This brings us to the world curve. Any earthquake will have a blip on the world standard of living. We know that just a small increase saves many life-years, due to better education, mobile phones, laptops for children, etc. A small dip or slowdown can affect millions, and perhaps shorten their lives. The effect may be far beyond any local effect, such as in Haiti.
Our main object in earthquake prevention, is to minimize these curves, especially the world curve. We can reduce the extent of the dip, and steepen the recovery phase. All this comes at the cost of carefully 'investing' that billion dollars I have in my pocket for this type of work (I wish!). After all, a billion put in one thing, cannot be put in another.
-to be continued.