PSN-L Email List Message

Subject: Re: Lehman help
From: n0cwr@.........
Date: Mon, 17 Jan 2000 14:49:56 +0000

Hi Jim
I seen your post was 1/9/2000 and appeared ready to start getting
some reads. 

My last "clean" read of an event was 1/8/2000 (M 7.1 from Tonga Islands)
I see a lot of events superimposed in the noise but not worth
sending to the group.

In the midwest, I think,  readable events are a bit slower than for
those that are out in the Pacific or California.

But I am wondering?, you may have been able to see the Maine 3.4?

I came in this morning to find the boom of the Lehman over to it's stop.
Flat line on the screen. I have the period set to 16/17 seconds and I am
considering dropping it back. This has happened several times now. 
The concrete, I guess that it is setting on shift's. Or, things change
somewhere just a micron here or there.

I didn't have to adjust it even at 14 second period. 
Sensitivity compared to when I started and I had it set to it's easy to
attain 12 second period?... 
I don't think I've noticed a difference other than the noise floor is
much higher now and I have to adjust it periodically.  

I'd think that location is everything. 
There isn't an abonded gold mine on my city lot! Darn!

I guess the point is, if the thing has set over night flat lined, what 
good did the longer period do. With local noise, most of the weaker reads
I get have to happen during the quiet time of night.

I was hoping to see if I could of detected the Maine 3.4 superimposed
in the noise but...., _______________________________________________ !
At 11:31 PM 1/9/00 -0500, you wrote:
>Thanks to Jim and Kevin,  I now have a Lehman boom that is beginning to
>behave correctly.  Thank you both for you help.
>In measuring the 'period' of the boom,  is this the measurement of time it
>takes the boom to swing "out and back", when pushed,  or the time it takes
>for the oscillations to die out completely?  If I manually deflect the boom
>~1" off of center,  is the period the time it takes the boom to come back to
>center,  or the time it takes the boom to move out to one side and then
>back past center to the other side?
>I know these are VERY elementary questions for this list,  but hey, I've got
>to start somewhere, don't I ?
>My thanks in advance to anyone who wishes to help me out.
>Jim Martin
>New Haven, Indiana
>Public Seismic Network Mailing List (PSN-L)
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Larry Cochrane <cochrane@..............>