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Subject: book "About Earthquakes" (1956)
From: ted@..........
Date: Mon, 31 Jul 2000 10:42:14 -0400

I came across a copy of this book by G. Eiby of the Wellington (NZ)
Seismological Observatory.  Written for the layman, it is easy to
understand and covers a lot of material.  Does anyone know if Mr. Eiby is
still around?  The book was published in 1956, so maybe not...

He begins:  "Earthquakes were among the earliest discoveries to be made in
New Zealand.  Members of Captain Cook's expeditions felt them in the
eighteenth century, and within ten years of the founding of Wellington, the
colonists lost their chimneys."   I greatly enjoyed his style of writing.

One very interesting quote (in this age of digital everything) concerns
using analog (electrical) models of buildings to assess their earthquake
safety.  Here's a quote:

"Most building codes today lay down some definite value of horizontal
acceleration which a  building must withstand.  In New Zealand, the value
varies from 0.08 to almost 0.16 G...  This type of code is gradually being
replaced by a more elaborate consideration of the dynamic characteristics
of the building, and use is now made of electrical models or "analogues" of
the structure.  The analogue is an electrical circuit in which the values
of the components are arranged to give them a response to electrical
vibrations that can be compared with the mechanical properties of the
building.  An ingenious photo-electric device then converts the record of
an earthquake into a varying electrical current which can be passed through
the analogue, which is [then] studied by the techniques of electrical

Would anyone have any idea how this "ingenious photo-electric device" for
converting paper traces into voltage signals might work?  I'm guessing
there must be some sort of activity in the field of Seismology to digitize
old paper seismograms, so maybe there are actual commercial devices to do
the work now.

Ted Blank


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Larry Cochrane <cochrane@..............>