Hi everybody.
We have some H/V curves, obtained by microtremor recordings. The problem is that the motion components are not accessible anymore. Can we extract ellipticity curve some how, to use in elipticity inversion technique to evaluate alluviums velocity profiles ?
We use "dinver" in Geopsy pack for velocity analysis.
Thanks
It is indeed possible to get ellipticity curves directly from the H/V curves. This option is available in Denver. As input, you have to enter the resonant frequency along with your desired band of frequency. For details, have a look at the following paper.
Article Shear Wave Velocity Estimates through Combined Use of Passiv...
Dear Dr Biswas,
Thank you for your response.
As you know there is an 'HVTFA' tool defined in geopsy which creates probability density ratios for all frequencies as a *.max file,
which will later converts to ellipticity curve using Max2curve tool.
the output of max2curve which is ellipticity against frequency is needed for inversion in Dinver. I cant find any option in dinver to define H/V directly as the input for inversion.
I looked the paper you mentioned. what I understood was that you employed the same method i mentioned above. my problem is that i dont have the motion component, so I cant employ HVTFA in Geopsy to create *.max file. I need a method to convert the "H/V" curve to "H/V ellipticity" curve.
I would be grateful if you can show me the way.
With dinver from geopsy it is possible, but you should consider the H/V cruvi FROM the main peak on.
You can also take a look on what we did some years ago:
Article H/V spectral ratio analysis and Rayleigh modelization in Eas...
Best regards :)
Dear Hortencia, thanks for your help.
Can you please take a look at the attachement?
is that the part you mean? There is no simple H/V option.
As far as I know the "H/V ellipticity" option needs ".max" file from Geopsy which I don't have, because motion components are needed to create it.
I have no idea which option i can use. I just have a "txt" file containing Frequency against H/V.
Thank you.
here's all I've got here.
I would be grateful if you can show me what to do. thank you so much.
Hey Shahram,
I think it's too late to respond to your question, but in case you still need the answer.
If you have the processed H/V data, then why do you need the raw three components recordings? From your H/V curve, you can either put the ellipticity peak along with a misfit weighting factor (0.2 suggested) or just input the whole H/V curve for the joint inversion in Dinver. But, be cautious with the weighting factor assigning to Dinver.
But, if you want to construct the low frequency part of a dispersion curve from the H/V measurements, it is a different story and I can give you some documents to read through that could help.
Best,
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