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 __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>