PSN-L Email List Message

Subject: Re: Okhotsk quake
From: Bob Hancock carpediem1@.........
Date: Mon, 24 Nov 2008 07:57:14 -0700

Steinar -

This was a deep focus event  (487.5 km) and the wave pattern is  
different that what you see with shallow events.  In this case some of  
the body wave phases are more pronounced and the surface waves are  
diminished.  For comparison, I would suggest that you download this  
event through the Wilber II option on the IRIS web site at:

There is a station near Oslo, Norway that has good data you could use  
for comparative analysis.  The station is part of the IU network  
(Global Seismic Network).  The station name is KONO, and its location  
is Kongsberg, Norway at 59.65 N and 9.60 E.  You can see a strong  
signal for the P wave on all three channels.

Bob McClure has written a small program that converts SAC files to PSN  
files which can be downloaded at:

Once you convert them to PSN format, you can edit the files to make  
them the same size and with the same starting times, after which you  
can put them into three file datasets.  By opening a second window on  
WinQuake, you can conduct detailed comparative analysis between you  
recordings and those of station KONO..

Good Luck

Bob Hancock
Tucson, AZ

On Nov 24, 2008, at 7:25 AM, Steinar Midtskogen wrote:

> Today's 7.0 Okhotsk quake was recorded by my SEP seismometer.  Not a
> huge signal, but clear enough.
> Sac-file:
> PNG image:
> However, what's a bit surprising is that at the exact same time of the
> arrival of the P wave my 4.5 Hz geophone recorded something pretty
> strong as well for a few minutes.  Mostly in the Z direction but
> clearly in the other directions as well.
> Sac-file Z:
> PNG image Z:
> Sac-file N:
> Sac-file E:
> Will a quake nearly 7000 km away every show up on a 4.5 Hz geophone?
> Or could a distant quake trigger a small local quake?  Or are the
> events unrelated?
> Since this happened in daytime, and it's a bit windy outside today
> also, there is quite a bit of noise, but the quakes are clear enough.
> -- 
> Steinar Midtskogen
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