PSN-L Email List Message

Subject: Re: book "About Earthquakes" (1956)
From: Mark Robinson other@...............
Date: Tue, 01 Aug 2000 03:12:39 +1200

Hi Ted,

George is sadly no longer with us. He worked at the Institute of
Geophysics here in Wellington as I recall. He has published a number of
books, many aimed at laymen, Earthquakes was published in a revised
edition in the 80s. And Volcanoes was published about the time George
died which is a while ago now.

George was a keen actor, enjoying Shakepearian roles.

No idea about the ingenious photoelectric device, but I would suspect
some kind of flying spot scanner, with a ramp in sync with the spot 
being sampled when black paper was seen. A fax machine would be a good
start these days.

The analogue computer sounds like a work of art. I will endeavour to
turn it up.


ted@.......... wrote:
> 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
> engineering."
> 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.
> Regards,
> Ted Blank
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Larry Cochrane <cochrane@..............>