Jeanne Hedge asked (9/14/96)

Does anybody know if its been determined why some buildings built to the
"earthquake proof " Japanese building codes collapsed during the Kobe quake?

Yeah.  It's simple really.  The engineers decided what a worst possible case
scenario earthquake could be, based on previous data and known fault lines.
 Then they added an "adequate" safety factor to allow them room for Mother
nature to surprise them.  So they had all the buildings built to withstand
something like an 8.7 on the Richter scale.  Unfortunately the actual Kobe
quake set all sorts of new records and hit .2 higher than that.  (I may have
the standard number wrong but the difference in Richter scale I am confident
is correct.)  Since the Richter scale is a logarythmic scale that means that
the quake was more than twice as strong as the designed for worst case.
 Unfortunately the engineers guessed wrong for their fudge factors.  Nothing
else was wrong, they just underestimated the destructiveness of the next
quake.  For example, the Japanese codes would have had every building built
to those codes surviving something the magnitude of the LA quake last year.  

I hope that answers your question.  

                          -Mike