Gary,

Yes, we're watching them, too.  The whole earth can vibrate in many 
modes.  The lowest has about a 20 minute period and I think that some 
oscillation modes have been observed up to about a 200-second 
period.  Though I doubt if it means anything, the 4S0 mode has a 
period of about 243 seconds.  We're also trying to figure out if it 
could be something else, though that could possibly be the explanation.

Brett



At 08:17 PM 3/11/2011, you wrote:
>After 19 hours the earth's ring is starting to subside. I measure a 
>period of about 240 seconds or so. Is that the period of the earth's 
>natural frequency. All day my vertical seismometer's most sensitive 
>output has been ringing like a bell. It's difficult to see through 
>the output of the initial M8.9 quake and all the aftershocks.
>Gary
>
>
>
>
>
>
>
>
>Gary Lindgren
>585 Lincoln Ave
>Palo Alto CA 94301
>
>650-326-0655
>
>www.blue-eagle-technologies.com 
>Check out Lastest Seismometer Reading
>cymonsplace.blogspot.com
>sites.google.com/site/seismicsensorinfo/Home 
>Design Details for New Vertical Seismometer
>
>


Gary,


Yes, we're watching them, too.  The whole earth can vibrate in many
modes.  The lowest has about a 20 minute period and I think that
some oscillation modes have been observed up to about a 200-second
period.  Though I doubt if it means anything, the
4S0 mode has a period of about
243 seconds.  We're also trying to figure out if it could be
something else, though that could possibly be the explanation.


Brett





At 08:17 PM 3/11/2011, you wrote:

After 19 hours the earth's ring
is starting to subside. I measure a period of about 240 seconds or so. Is
that the period of the earth's natural frequency. All day my vertical
seismometer's most sensitive output has been ringing like a bell. It's
difficult to see through the output of the initial M8.9 quake and all the
aftershocks.

Gary

 

 

 

 

 

 

 

 

Gary Lindgren

585 Lincoln Ave

Palo Alto CA 94301

 

650-326-0655

 


www.blue-eagle-technologies.com   Check out Lastest
Seismometer Reading


cymonsplace.blogspot.com 


sites.google.com/site/seismicsensorinfo/Home    Design
Details for New Vertical Seismometer