Like many cities on the coast, a lot of it is on fill. As an example:"... and liquefied much of the cities foundations ..."
So definitely a sub-surface burst, limiting the damage radius of the detonation but creating TONS of fallout.
Is Night City built on a landfill???
Ahhhh yes ... this is a real problem.It's cruel to keep the ETA for themselves, and I've a campaing to run If I start anything else about right now, the window of opportunity for cyberpunk closes until 2021-22