PSN-L Email List Message

Subject: Re: Instrument quality - microseisms
From: George Bush ke6pxp@.......
Date: Thu, 22 Oct 2009 09:35:10 -0700


Hi- I uploaded the files on Sneaker waves, sorry that I didn't 
identify where they were from.

Whenever I see this pattern I send a notification out on our local 
email list so the people along the coast up here North of San 
Francisco will be careful near the water. I made the upload so that 
local folks could see what the seismic signal from two storms causing 
beat patterns in the incoming waves and causing quiet periods where 
the waves are out of phase and then when they get in phase the BIG 
waves SNEAK up on you! We have had high surf warnings here and so I 
am not surprised that the background microseismic activity is high right now.

My 24-hour heliplot shows this beat pattern quite clearly, check it 
out on my website at 
http://gbush.mcn.org/srn.gif.


At 06:57 PM 10/21/2009, you wrote:

>To all
>Related to instrument quality- maybe. I have noticed a lot more 
>microseismic activity the last few days. The background noise on my 
>vertical is around +/- 300 counts @  8.7 sec  and 6.6 sec  (two 
>narrow peaks). I don't remember this magnitude in years past. I'm 
>sure it is weather related. I live about 200 miles east of the west 
>coast of northern California. Anyone else noticed an increase in 
>background lately? Every time I look at the output I think I'm 
>looking at surface waves after an event.
>Barry


George Bush
Sea Ranch, CA, USA


Hi- I uploaded the files on Sneaker waves, sorry that I didn't identify
where they were from. 

Whenever I see this pattern I send a notification out on our local email list so the people along the coast up here North of San Francisco will be careful near the water. I made the upload so that local folks could see what the seismic signal from two storms causing beat patterns in the incoming waves and causing quiet periods where the waves are out of phase and then when they get in phase the BIG waves SNEAK up on you! We have had high surf warnings here and so I am not surprised that the background microseismic activity is high right now.

My 24-hour heliplot shows this beat pattern quite clearly, check it out on my website at http://gbush.mcn.org/srn.gif ..


At 06:57 PM 10/21/2009, you wrote:

To all
Related to instrument quality- maybe. I have noticed a lot more microseismic activity the last few days. The background noise on my vertical is around +/- 300 counts @  8.7 sec  and 6.6 sec  (two narrow peaks). I don't remember this magnitude in years past. I'm sure it is weather related. I live about 200 miles east of the west coast of northern California. Anyone else noticed an increase in background lately? Every time I look at the output I think I'm looking at surface waves after an event.
Barry


George Bush
Sea Ranch, CA, USA
38.73775N, 123.48882W


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