# Thread: Calculating kappa-parameter in SAC

Started: 2020-09-15 21:44:38
Last activity: 2020-09-17 09:02:43
Topics:
Rinne, Lauri A
2020-09-15 21:44:38
Hi!

I am a geophysics master's student in University of Helsinki, Finland. My thesis includes kappa-calculations and I've opted to do this calculations with SAC. So far everything has gone well, I've managed to do the noise- and S-wave spectral plots. Next step would be to apply a best-fit line on part of the S-wave spectra, from which the kappa-parameter could be calculated. I've been unable to find the right commands to do this however and I was wondering if you could provide some technical assistance on how can I plot this line in the S-wave spectra between two points.

Thank you!

Best regards,
Lauri Rinne

• Cliff Thurber
2020-09-16 21:00:42
Hi Lauri. This tutorial might have the answer.

http://www.ceri.memphis.edu/people/rsmalley/ESCI7205F2009/Lecture9.pdf

Good luck.

Cliff Thurber

On Sep 16, 2020, at 3:50 PM, Rinne, Lauri A (via IRIS) <sac-help-9187.97987-bounce<at>lists.ds.iris.edu> wrote:

﻿

Hi!

I am a geophysics master's student in University of Helsinki, Finland. My thesis includes kappa-calculations and I've opted to do this calculations with SAC. So far everything has gone well, I've managed to do the noise- and S-wave spectral plots. Next step would be to apply a best-fit line on part of the S-wave spectra, from which the kappa-parameter could be calculated. I've been unable to find the right commands to do this however and I was wondering if you could provide some technical assistance on how can I plot this line in the S-wave spectra between two points.

Thank you!

Best regards,
Lauri Rinne

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• George Helffrich
2020-09-17 09:02:43
Dear Lauri -

There are a couple of ways to do this, with tradeoffs between flexibility and ease of use. They are best used by making your analysis procedure into a SAC macro script and generating the line parameters from your signal analysis results. From the simplest to the most complex approach:

1. FUNCGEN LINE will create a SAC seismogram that is a line; you can use P2 to overlay the line plot on your data.

2. READTABLE will read in an arbitrary curve of X-Y data. Read the X-Y points written out by your analysis as a seismogram and plot them using P2.

3. Annotate your plot using PLOTC. Your analysis procedure creates a SAC macro file that you replay along with your seismogram plot to add points, lines, text, etc. to show the results.

See chapter 7 of the SAC book for a lot of information about how to do this, and chapter 11 for some real examples.

On 16 Sep 2020, at 21:46, Rinne, Lauri A (via IRIS) <sac-help-9187.97987-bounce<at>lists.ds.iris.edu> wrote:

Hi!

I am a geophysics master's student in University of Helsinki, Finland. My thesis includes kappa-calculations and I've opted to do this calculations with SAC. So far everything has gone well, I've managed to do the noise- and S-wave spectral plots. Next step would be to apply a best-fit line on part of the S-wave spectra, from which the kappa-parameter could be calculated. I've been unable to find the right commands to do this however and I was wondering if you could provide some technical assistance on how can I plot this line in the S-wave spectra between two points.

Thank you!

Best regards,
Lauri Rinne

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George Helffrich
george<at>elsi.jp

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