HVSR by having a soil profile?

[Pourya]

Hi Marc,

Is it possible to get HVSR results based on a known soil profile? I mean somehow modelling the noise and drawing the soil profile and getting the HVSR results on any location on the surface?

[admin]

Hi,

Simulating HVSR curves can be achieved with various approaches: Arai and Tokimatsu (2004), diffuse wavefield assumption (Sanchez-Sesma et al. 2011) and only the Rayleigh wave ellipticity (eventually assuming an certain amount of Love waves). Each of these methods has its assumptions about the structure of the ambient wavefield and hence its limited validity to interpret experimental results. Geopsy package provide tools only for the latter. The implementation of the other techniques has always been in mind but not yet in code.

Best regards,
Marc

[Pourya]

Thanks Marc. Based on what I got, Geopsy is capable of simulating hvsr using the Rayleigh wave ellipticity technique. Am I right? if yes, is there any example I can follow? any recommendation?

[admin]

Hi,

Use gpell in a console. (under Windows GeopsyLand.exe does the job)

Code: Select all

$ cat M2.1.model | gpell
# 1 Rayleigh ellipticity mode(s)
# h vp vs rho Qp Qs
# Mode 0
0.200885573645323 -0.688236449998145
0.205907712986456 -0.689653015270422
0.211055405811117 -0.691114967995931
...

The content of the model file is:

Code: Select all

$ cat M2.1.model
# h vp vs rho Qp Qs
2
25 500 200 1900 50 25
0 2000 1000 2500 100 50

gpell has plenty of options documented if you run

Code: Select all

$ gpell -h all

Best regards,
Marc

[luigiV]

Hi Marc,
what is the difference between the two scripts:
$ cat myfile.model | gpell
$ gpell myfile.model?
are scripts homologous? The risults are the same..

Regards
Luigi

[Pourya]

Thanks, Marc for the information. Since we can model the HVSR recordings, is it possible to jointly invert for the soil profile velocity using HVSR and MASW data in Geopsy?

[Pourya]

Marc,

this is what I got from your proposed model! does the result make sense??

Capture.PNG

(46.73 KiB) Not downloaded yet

[admin]

@Luigi, yes these two scripts are strictly equivalent. The first one uses the pipe mechanism provided by the shell, while the second form provides the file name to gpell which in turn open and read the file, job done by cat utility in the first form.

@Pourya, this is the signed ellipticity. To get a more classical output on a log scale, add option '-abs' to gpell to get the absolute value of the ellipticity.