Hi Chris -

Cold fronts can generate increased wind velocity.  This in turn moves trees
and buildings, and this is visible on seismometers; however, this does not
appear to travel long distances.  This is readily visible on the
seismometers located in the Long Valley Caldera, Mammoth Lakes, CA, an area
subject to high winds.

However, ocean storms, particularly when they come ashore can increase
seismic background noise that travels for thousands of kilometers.  This is
observable when major storms or hurricanes and typhoons occur.

In addition, low frequency background seismic noise is more pronounced on
seismic stations located on small islands =AD such as Pitcairn Island, Wake
Island, and many others all around the world.  This is at a much lower
frequency than is normally associated with microseisms , and I do not know
if would be classified as a microseism.

Cheers

Bob Hancock

 =20


On 4/11/08 8:06 AM, "ChrisAtUpw@......."  wrote:

> In a message dated 2008/04/11, carpediem1@......... writes:
>=20
>> As you said, microseisms are generated world wide when ocean waves strik=
e
>> shore.  The strength of the microseisms are largely dependent upon the s=
ize
>> of the waves that come ashore.
>=20
>=20
> Hi Bob,
>=20
>        Not generally I think. There is an ocean area S of Greenland and
> another on the continental shelf off the NW coast of Norway which dominat=
e the
> Atlantic systems. You can also get 10 to 12 second stuff from storms dire=
ctly
> coming on shore, but that is different.
>        Cold fronts can also have a lot of seismic noise on them, as Geoff
> observed.
>=20
>        Regards,
>=20
>        Chris Chapman







Hi Ch=
ris -



Cold fronts can generate increased wind velocity.  This in turn moves =
trees and buildings, and this is visible on seismometers; however, this does=
 not appear to travel long distances.  This is readily visible on the s=
eismometers located in the Long Valley Caldera, Mammoth Lakes, CA, an area s=
ubject to high winds.



However, ocean storms, particularly when they come ashore can increase seis=
mic background noise that travels for thousands of kilometers.  This is=
 observable when major storms or hurricanes and typhoons occur.



In addition, low frequency background seismic noise is more pronounced on s=
eismic stations located on small islands – such as Pitcairn Island, Wa=
ke Island, and many others all around the world.  This is at a much low=
er frequency than is normally associated with microseisms , and I do not kno=
w if would be classified as a microseism.



Cheers



Bob Hancock



  





On 4/11/08 8:06 AM, "ChrisAtUpw@......." <ChrisAtUpw@.......&g=
t; wrote:



In a message dated 2008/04/11, carpediem1@......... writes:



As you said, microseisms are generated world wide when =
ocean waves strike shore.  The strength of the microseisms are largely =
dependent upon the size of the waves that come ashore.





Hi Bob,



       Not generally I think. There is a=
n ocean area S of Greenland and another on the continental shelf off the NW =
coast of Norway which dominate the Atlantic systems. You can also get 10 to =
12 second stuff from storms directly coming on shore, but that is different.=


       Cold fronts can also have a lot o=
f seismic noise on them, as Geoff observed.



       Regards,



       Chris Chapman