The main epicentre is located by seismometers and is at the top of the rupture. This is called a subduction zone, but you can see a real subduction zone right beside it.
These are not what I call 'clean' subduction zones, and may only produce M9's rarely, or not at all. The M8 earthquake produces the maximum of what we can expect for an earthquake, but an M9 shakes longer. You will never get the pgv higher than this, whatever it is.
However, thousands of structures have been weakened by this earthquake, and I would call it quite likely that another one goes off on either side of the basin. It seems similar to Christchurch.
So, in a few months, all buildings that 'look alright' will be cleared. Then, bang! Another one. I give this a good likelihood, but who am I?
If you want to live in a building here, try to get pictures of it being constructed. The steel will be obvious. If you had followed my 'Handy Dandy Guide to Riding Earthquakes' you would have measured the seismic noise when built, and now check it after the earthquake. It should show no difference. If the building has softened, get out of Dodge.
Anyway, my official opinion is to believe everything they say.
ps what I really wanted to say is that in all these earthquakes, the highlands go up, and lowlands go down. The topography tells you a lot.
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