John,
You asked a couple of questions after giving us the link to the Global
Displacement Wavefield. I started to write up a quick answer, but since =
I'm
new to the group I thought I better find out a bit more about who was =
asking
the questions. I'm glad I did. I'll leave the questions unanswered for
others to ponder. I presume after some reasonable amount of time, you =
will
provide the answers.=20
-Tim-
Timothy Carpenter, P.E., Pres.,
GeoDynamics Consultants, Inc.
5043 Whitlow Ct.
Commerce Twp., Mi 48382
248-363-4529 (voice & fax)
248-766-1629 (cell)
geodynamics@........... (primary)
geodynamics@....... (secondary)

-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... =
On
Behalf Of twleiper@........
Sent: Thursday, January 06, 2005 2:38 PM
To: psn-l@..............
Subject: Re: Surface waves from Sumatra M 9.0, 2nd Version

I would suspect destructive interference of the wave fronts
at the quarter-wave point (50 minutes) assuming the resonance
of the "global tank circuit" is 200 minutes. Either that or
some type of phase shift. How about the coriolis effect ? :-)

-- John or Jan Lahr  wrote:
If you haven't taken a look at the IRIS "Image of the Week" yet,
check out this page (with the now correct URL!):
http://www.iris.edu/about/ENO/iow.htm

The image shows seismic records from stations distributed around
the globe and surface waves that traveled twice around!

Questions to think about --  Why does the y-axis stop at 180 degrees?
Why would the amplitude of the surface waves fall off around 90 degrees
and then increase at 180 degrees again?

Cheers,
John=20
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