PSN-L Email List Message

Subject: Re: Detecting micro-earthquakes
From: Roger Sparks rsparks@..........
Date: Sat, 11 Feb 2006 10:53:29 -0800

Hi All,

Hi Jon,

You definitely have detected some events.   Congratulations.

We had a M2.9 event about 102 km from Ellensburg last night.   I posted 
both a filtered and unfiltered version on the PSN site.

The unfiltered recording vividly demonstrates how the high frequency 
local quake can ride on the noise from ocean waves.   Ellensburg is very 
roughly 200 miles from the ocean.

Your location at 300 meters from the ocean must be very noisy as you 
have indicated.   Your problems are far different from mine.

Best wishes,  Roger

psn-l-digest-request@.............. wrote:

>.------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
>| Message 1                                                           |
>'------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
>Subject: Re: Detecting micro-earthquakes
>From:    =?ISO-8859-1?Q?J=F3n_Fr=EDmann?= 
>Date:    Fri, 10 Feb 2006 10:38:13 +0000
>To Roger.
>I did in the end figure out that i didn't detect the earthquake at that
>range. It was out of my range, after all i didn't see any change in the
>graph as i did go down to 10 seconds on the X scale. I also now got a
>comparison, i did detect a mag 2.2Ml (unconfirmed size) earthquake this
>morning (05:01 GMT), it did happen when there is minimal noise from
>traffic and other cultrual noise sources. I was able to detect the S
>wave of the quake, but the recording is really poor.
>As for the 10 to 20Hz noise, i am unsure what you mean.But i am close to
>the ocen, about 300 meters from the beach. There are many noise sources
>where the geophone is located at the moment (for instant the wind noise
>is hig, even if the geophone is located inside the house), at the moment
>i can't move the geophone to better location, becose of house i life in.
>But i plan to move the geophone in next 6 to 8 months, when i can buy
>the needed hardware to move the geophone.
>If i rember correctly, the noise level is almost none when i do
>disconnect the geophone from the psn board. But i am not sure, i will
>check this when i move the geophone. The geophone is also located 2
>meters (max) from a solid bedrock. That problay goes down to ~35km into
>the crust, becose it is an old volcano that the town is build on top of
>(in the side of it).

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