PSN-L Email List Message

Subject: Re: New WinQuake Beta Release
From: "Larry Cochrane" cochrane@..............
Date: Sun, 26 Jan 2003 13:17:04 -0800

Hi John,

----- Original Message -----
From: "John & Jan Lahr" 
Sent: Sunday, January 26, 2003 7:44 AM
Subject: Re: New WinQuake Beta Release

> Hi Larry,
> Sounds like a lot of helpful new features for WinQuake.
> In your magnitude calculations, do you account for the variation
> in overall gain between ~1s P waves for mb and ~ 20 s surface
> waves for MS?  To a first approximation if the gain of the system
> were know at these two frequencies, that would be enough for
> rough magnitude determinations.

WinQuake uses 1 second and 20 seconds for the default P and S waves periods.
The user can determent the approximate period by zooming into either the P
or S wave peak point and then calculating the period. What WinQuake does is
look for the peak amplitude point in the window view (not the whole event
file), it then looks for the two zero crossing points on either side of the
peak wave and calculates the period using the number of samples between the
zero crossing points and the sample rate. Since WinQuake only looks for the
zero crossing point of 1/2 of the wave, it multiplies the period number by 2
to come up with the actual period number.

> AmaSeis does not write the new PSN Type 4 format now.
> What would be the advantages of making this change?  Can
> the old format be converted to Type 4 and then the file augmented
> with additional data, or does the change need to be made
> in AmaSeis?

AmaSeis would need to be modified to support the PSN Type 4 format. That's
the only way to easily supply all of the new data types to WinQuake. The
other way would be to come up with a conversion program. The additional data
items could be saved in a file keyed off of the station/sensor ID. The
conversion program would use what it can from the AmaSeis event file and
then look up the sensor in the data file for the additional information.

Larry Cochrane
Redwood City, PSN


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