Saturday, January 2, 2016

Chances of Death from Earthquake


A lovely happy scene in front of a horrible brick monstrosity.  What are the chances of death?  Are they any more than anything else that tries to kill you?  I would draw the line at 10%, that is, if something is less than 10% of daily activities, such as driving to the cottage, then forget it.

I don't know why people accept the bland assurances of officials.  Based on what?  But we accept things without physics all the time, and I've said that physics is on a downhill run.

I was asked to look at a particular fault in the Philippines, to see if it presented any danger to that person.  Forget that concept!  That is a stupid California concept, that you can tell something by reading the tea leaves of criss-crossing faults.  Just accept the fact that the whole thing is a mess.  In those areas, and in fact, in most areas of the world, your chances of death are dominated by foundation and construction.

Foundations can amplify the PGV by 10 to 100 times.  That totally wipes out any variation by location.  There is a similar factor of 10 to 100 in the seismic capacity of structures.  Again, forget individual faults, that's just a feather-bed for the California Seismologist Evil Cabal.  :)

The seismic capacity to death is very low for adobe houses with heavy clay roofs, perhaps 10 cm/s or less.  A standard frame house has something like 1-2 m/s capacity before death, depending on the roof and chimney.  In between are brick monstrosities, and 70's pre-stressed concrete buildings.

We need a cloud of accelerometers to give a more accurate picture of the chances of death.  If that school would have had a PGV ten times lower than the average, then we know it is on rock, and will never be damaged.  If it would be 10 times more, then shut it down!  This is physics, and something that will never happen.

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