[APG Public List] Regarding GPS

Ray Beere Johnson II raybeere at yahoo.com
Mon Nov 1 18:54:23 MDT 2010

--- On Mon, 11/1/10, John Yates <john at jytangledweb.org> wrote:

> In a chosen coordinate system, the coordinates of a precise place won't
> change. If they do, it exposes a flaw in defining the coordinate system.
> Are there flaws in latitude longitude? Yes. One is continental drift.
> Sizable over millennia. Not so much in a lifetime. Catastrophic events
> like bomb blasts, earthquakes, etc. Possible, but rare.

     Although I have never heard of any bomb blast physically shifting the underlying land (as opposed to simply throwing up a lot of topsoil), earthquakes are another matter. How much did the New Madrid earthquake in the early eighteen hundreds displace locations in that area? Does anyone even know for certain?
     An earthquake in Chile in 1960 altered the landscape and changed the course of rivers. Another quake in Chile shifted some locations at least ten feet. In the 1906 San Francisco earthquake, ground along some parts of the fault shifted even more drastically than in Chile. Those are just the ones that occurred to me when I read your post; I am sure there must be others.
     In other words, such disturbances to the correspondence between a particular point of land and certain co-ordinates are not so rare that we can afford to ignore them.
                            Ray Beere Johnson II


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