Anchorage, Alaska earthquake -- almost no structural damage

I'm reading all the reports now, and if you were on stable ground, the pgv did not exceed 30 cm/s.  Structural damage begins at 50 cm/s.  This is consistent with the only full strong ground motion coming out of the place.  I'm guessing all the other accelerometers fell off their perch.

However, I believe there was softening in the concrete structures, and this will not be addressed.  However, the coming M8 will overwhelm any of this.  If you got another M7, then softening would come into play.

But, it's Christmas time, and I hope everybody cleans up and has a good party.  You'll have time to put everything on piles next year.

Basic Physics - there is a contention in the earthquake biz on what's the best parameter for damage.  I push for pgv, and California pushes for pga (peak ground acceleration).  pga saturates on soil to about 1 g, and is actually less on soft soil than rock.  pgv is directly related to base shear, while pga has no physics, since related force becomes a function of frequency.

ps. 

Ground velocities are dribbling in.  Looks like basement was less than 10 cm/s, and roof was 75 cm/s.  Some good resonance there.  Top of the building was 0.6 g.  This was a totally small earthquake.