Friday, August 14, 2015

Earthquake Stupidity #1 -- Evacuation of High Rises

This is my new series on major earthquake stupidities.

Every little earthquake rumble sends all the occupants of high rises onto the streets.  This is an immediate, near panic evacuation.  As well, the fire alarms go off, and for larger earthquakes, the main power is lost.  This is right after duck and cover, but most people don't do that.

In most cities, like Tokyo and New York, there isn't enough room for everybody.  It's bad enough they evacuate for tiny M6's and 5's, but a real earthquake would loosen glass, and out it flies on a windy day.  A crowd has not yet been decapitated by a giant pane of glass, but it will happen one day.

For New York, the most likely scenario is a Grand Banks-type shelf earthquake.  That should not bother the high rises on rock, but will send a horrendous tsunami.  Is this the time to pack the streets, ferries, and subways?

All high rises should be instrumented for PGV at the base (at the very least).  Then, there should an 'earthquake override' for the fire alarm.  Then there should be an automatic PA announcement:

"You have probably noticed already that we are experiencing an earthquake.  Our instruments have noted that there is no chance of strucural damage to this building, and the fire alarm has been overridden.  Do not evacuate at this time.  Please tend to your neighbour if there are minor injuries from falling objects.  The whole city is now in this situation, and we await further information."

As I have mentioned with the other stupidities, there is no chance of this being implemented anywhere.  We have to wait for unnecessary deaths.  :(

Along with this goes the next stupidity  -- Stupid early warning systems that give seismologists lots of money.


Anonymous said...

So does this apply to our skyscrapers in Toronto. I assume the tall condos built on rock downtown are safe? How much of an earthquake can they take?

Harold Asmis said...

The bank towers are on rock and built like a rock. They should not evacuate. The waterfront condos should stand even though the soft-story ones will be damaged. Again, I'm expecting a huge lake seiche (sort of tsunami) from a 7, and everybody should stay put.

Anonymous said...

Is it true that tall buildings are inherently safer due to their long period natural frequency?

Harold Asmis said...

Tall buildings are safer because they must have a solid foundation. Also, they are designed for wind, which puts more of a load than seismic.