In a message dated 03/04/2005, mark.robinson@............... writes:

> Speaking of warning of earthquakes, I made an offhand prediction that 
> there was going to be a significant earthquake six hours or so before 
> the 8.7 in Indonesia.
> 
> This was based this on unusual long period activity on the USGS 
> instrument in Wellington which I have associated with the run up to 
> large quakes in the past. Strange patterns of waves of similar period to 
> the global ringing which happens after a large quake.
> 
> Perhaps some of the learned people here could tell me if this is a known 
> phenomenon and if so point me at some reading material.

Hi Mark,

       I was certainly aware of these eigenmode signals, which are a bit 
difficult to see on 'ordinary' seismometers, but I do not offhand know of any 
reports. There certainly should be some about. You can also see these effects with 
a really sensitive tiltmeter.

       Regards,

       Chris Chapman
In a message dated 03/04/2005, mark=
..robinson@............... writes:



Speaking of warning of earthqua=
kes, I made an offhand prediction that 

there was going to be a significant earthquake six hours or so before 

the 8.7 in Indonesia.



This was based this on unusual long period activity on the USGS 

instrument in Wellington which I have associated with the run up to 

large quakes in the past. Strange patterns of waves of similar period to 
the global ringing which happens after a large quake.



Perhaps some of the learned people here could tell me if this is a known 
phenomenon and if so point me at some reading material.




Hi Mark,



       I was certainly aware of these eigenmod=
e signals, which are a bit difficult to see on 'ordinary' seismometers, but=20=
I do not offhand know of any reports. There certainly should be some about.=20=
You can also see these effects with a really sensitive tiltmeter.



       Regards,



       Chris Chapman