Hi Kay,

At 06:57 PM 9/8/2010, you wrote:
>Dear friends,
>
>John Lahr's wife, Jan, gave me much of John's earthscience 
>activities and experiements.  I'm familiar with most of them, but 
>there is one in particular that I could use some help on.  I have 
>posted some pictures at http://www.oregonshakes.com/temp/Lahr/ for your review.
>
>The device appears to be a torsion wave generator but I'm not 
>familiar with torsion waves generated by earthquakes (which was 
>John's primary focus). Could this be something else related to earthquakes?

Most definitely.  To completely describe the motions of an object 
(like the ground under my house) during an earthquake requires six 
numbers, three representing linear motions (like N,E & Z) and three 
describing rotational motions.  Until the last decade or two, the 
rotations weren't much discussed or measured since, among other 
things, they are usually rather small.  In the last decade or so, the 
field of 'rotational seismology' has been gaining increasing 
attention.  Searching on that phrase will get quite a few hits.

>Be sure to look at the move link on the website so that you can see 
>it in action.
>http://www.oregonshakes.com/temp/Lahr/MOV04260a.MPG
>
>If any of you have ideas, please let me know.

Regards,
Brett 


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