Shonner,
Fantastic, simply fantastic...
First the AHLs, then the Broadsword, and now this...
Every the greedy gray-haired fat man, I've squirreled everything away in my Vault of Traveller Goodnesstm.
The Azun arcologies raise so many interesting questions, not the least of which is where on a planet's surface can/should you build something so FREAKIN' HUGE!
When you look at a city's skyline, that outline is very much shaped by the rocks beneath the city in question. In Manhattan for example, the larger skyscrapers cluster around midtown and Wall Street, not because of human considerations, but because a huge mass of old tough rock called Manhattan schist is either on or near the surface in those two areas. That schist provides a very good footing for very large buildings.
Many cities who wish to copy Manhattan's skyline don't have Manhattan's geology. They must building vast underground footings for their skyscrapers spending as much or more on foundations below the ground as they do on the actual buildings above it. The skyscrapers of Houston, for example, which squat in 400 meters of montmorillonitic clay resemble bowling pins with as much as a third or half of their overall structure buried in order to provide support for the rest.
At 3km in height, the arcologies of Azun therefore must be placed atop old tough rock unless there's a 2 or 3 km foundation beneath them.
That need, plus critical seismic concerns, are going to limit the placement of these huge arcologies. They'll be placed on the relatively stable interior continental cratons. Shorelines will rarely fit the bill, same with conglomerate terrains. Fault lines, despite the Imperium's technology, are best avoided too.
Arcologies won't be in places like Bermuda, Florida, Los Angeles, Tokyo, or Shanghai. They'll be in places like Omaha or Mukden instead.
Regards,
Bill