Marchal van Lare wrote:

> Hi all,
>
> One year ago I started recording earthquakes with three 4.5 Hz
> Mark Products geophones. These geophones are only sensitive to
> local earthquake activity.
>
> The problem is, I am missing the large distant earthquakes.
> To be able to detect the larger distant events I will need
> a long period seismograph.
>
> I tried to build my own device several times, but without good
> results.

Marchal,
Scavenger that I am, I am wondering if perhaps, your design/s,
maybe perhaps lacking in success due to perhaps one or two
parts.....usually the pivot or sensor/magnet, if its a horizontal?

Maybe the best approach is to give a description of what you
have now, and any kind of rough measured results....this could
give us a clue perhaps.

Not to be overlooked is potentially the problem of your pier,
what with the likely hood of your soft soils creating problems?


>
>
> My question is, do anyone know of any source where I can buy a good
> working seismograph or parts? Perhaps someone who is willing to
> build one for me?
>
>

Right off the bat, if you can afford the cost, Larry has a variety of
material on his web site.  Mechanically, I kind of like the S-G
variety, it doesn't present as much difficulty as say the normal
"garden gate seismometer".

Meredith Lamb





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