Estimate Vs30 using H/V

Discuss here all technical and scientific questions about the processing of ambient vibrations for site characterization (H/V, Array methods,...)
shaham
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Estimate Vs30 using H/V

Postby shaham » Thu Apr 14, 2011 5:14 am

Dear Dr.Wathelet
Recently, I read a paper (that is attached: "Vs30 estimates using constrained H/V measurements"); but I can't understand how I can use "Sesarray(Geopsy)" software to estimate Vs30 using single station data and some stratification data (e.g. soil layer's thickness). Could you guide me, please?
Thanks,
Shaham

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Postby admin » Mon Apr 18, 2011 7:55 am

Single station H/V measurements provide rich and useful information but the local ambient vibration recording conditions can strongly influence the shape of the obtained curves: energy ratio of Love/Rayleigh waves, predominance or not of body waves, higher mode surface waves, lateral variation of soil properties, anisotropy, source pattern, acquisition device,... See SESAME deliverable for detailed studies.

During Neries project, some work has been achieved about the extraction of Rayleigh ellipticity out of single station measurement, and its inversion for retrieving Vs profiles. Inversion of Rayleigh ellipticity. Geopsy module HVTFA implements such technique. Results are post-processed by max2curve and obtained ellipticity curve is inversed inside dinver. Such an inversion works only in combination with some prior knowledge of superficial Vs profile. The inversion has a strong trade-off between depth and velocity, impossible to resolve with ellipticity alone. Hence, a combination with ambient vibration array recordings is strongly advised.

Another technique has also been recently proposed by Manuel Hobiger called RAYDEC:

Hobiger, Manuel, Pierre.-Yves Bard, Cecile Cornou, and Nicolas Le Bihan. "Single station determination of Rayleigh wave ellipticity by using the random decrement technique (RayDec)." Geophysical Research Letters 36, no. 14 (July 2009): 0-4. doi:10.1029/2009GL038863.

This last method should be implemented in Geopsy software as soon as possible.


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