Noise windowing

[mcardenass]

Usually, extracting Green's function by ambient noise requires averaging or stacking correlations in several time windows over recording hours, for example, of a day. Does the code in the frequency domain already include noise windowing, or is it necessary to apply the code to several noise windows at a time and then average those correlations?

[geophydog]

Hi, the code here only shows an example of computing cross-correlation from earthquake coda or ambient noise, and it does not include stacking correlations. Thus, it is just a test. I don't use this code to extract empirical Green's function. I would like to show you a Python version code if you need.

[mcardenass]

Hi Xuping,

Your code is very interesting it makes me very versatile. This already includes normalization in time and frequency. I calculate the correlations using the correlate command in a sac macro, where I windowing the noise trace. I keep all the correlations from various time windows and then stack them using a phase-weighted stack. The sac macro increases the computation time, but the correlations (the dispersion curve) suit me better than if I use the GSAC program. If possible, thanks for showing me your Python code.

Regards

Martin

On Wed, Dec 13, 2023 at 9:59 AM Xuping Feng @.***> wrote:

Hi, the code here only shows an example of computing cross-correlation from earthquake coda or ambient noise, and it does not include stacking correlations. Thus, it is just a test. I don't use this code to extract empirical Green's function. I would like to show you a Python version code if you need.

— Reply to this email directly, view it on GitHub https://github.com/geophydog/ABC/issues/1#issuecomment-1854200829, or unsubscribe https://github.com/notifications/unsubscribe-auth/AQ5BBHC6HKDTTE3GKNUOLYTYJHGFNAVCNFSM6AAAAABATMNN7KVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTQNJUGIYDAOBSHE . You are receiving this because you authored the thread.Message ID: @.***>

-- Dr. Martín Cárdenas Soto División de Ingeniería en Ciencias de la Tierra Edificio A, Facultad de Ingeniería, UNAM Dirección Postal: Circuito Escolar S/N, Ciudad Universitaria Edificio Principal. 04510 Coyoacán, México, D.F.

Tel/Fax. (+55) 5622-0850 al 54 ext 421 Email: @.; @. @.***>

[geophydog]

Martín,

I have uploaded a data test for extracting empirical Green's function of two seismic stations (TA.N16K and TA.19K, installed in Alaska) at https://github.com/geophydog/Seismic_Data_Examples/tree/main/TA_test . There are some steps for doing so: (1) Execute "python overlap_ccf.py 2017-05 Z Z TA.lst" to obtain daily cross-correlations (SAC format); (2) You can stack daily correlations to get the final correlation by linear way or phse-weighted way (3) Execute "dispersion_curve_image_trans.py xxx.SAC 3 100 2 5 Z CCF" to show the two-station dispersion diagram, where "xxx.SAC" is the stacked SAC format data file, "3" and "100" are separately lower and upper periods, "2" and "5" are lower and upper phase velocity limitations, respectively.

Please feel free to contact me if you have any questions. Xuping

[mcardenass]

Xuping

Thanks a lot. I'll look at the Python codes and answer any questions. Until next time.

Martín

On Wed, Dec 13, 2023 at 9:42 PM Xuping Feng @.***> wrote:

Martín,

I have uploaded a data test for extracting empirical Green's function of two seismic stations (TA.N16K and TA.19K, installed in Alaska) at https://github.com/geophydog/Seismic_Data_Examples/tree/main/TA_test . There are some steps for doing so: (1) Execute "python overlap_ccf.py 2017-05 Z Z TA.lst" to obtain daily cross-correlations (SAC format); (2) You can stack daily correlations to get the final correlation by linear way or phse-weighted way (3) Execute "dispersion_curve_image_trans.py xxx.SAC 3 100 2 5 Z CCF" to show the two-station dispersion diagram, where "xxx.SAC" is the stacked SAC format data file, "3" and "100" are separately lower and upper periods, "2" and "5" are lower and upper phase velocity limitations, respectively.

Please feel free to contact me if you have any questions. Xuping

— Reply to this email directly, view it on GitHub https://github.com/geophydog/ABC/issues/1#issuecomment-1855078481, or unsubscribe https://github.com/notifications/unsubscribe-auth/AQ5BBHHX77AQBVIWBEHLFKLYJJYT5AVCNFSM6AAAAABATMNN7KVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTQNJVGA3TQNBYGE . You are receiving this because you authored the thread.Message ID: @.***>

-- Dr. Martín Cárdenas Soto División de Ingeniería en Ciencias de la Tierra Edificio A, Facultad de Ingeniería, UNAM Dirección Postal: Circuito Escolar S/N, Ciudad Universitaria Edificio Principal. 04510 Coyoacán, México, D.F.

Tel/Fax. (+55) 5622-0850 al 54 ext 421 Email: @.; @. @.***>