Although the link below is to a commercial site, the web-pages include some citations and they are informative with lots of graphics. I have no connection with the firm. http://masw.com/WhatisMASW.html

When you say "surface holes," are you referring to boreholes drilled from the surface down into the subsurface? Or are you referring to near-surface cavities?

What size of cavities are of interest?

For oil & gas field, body wave is the main signal whereas for Geotechnical study, Surface wave (Vs component) is the key parameter as it contains around 67% of the total seismic energy generated by an imapct of source on the surface.

Multichannel Analysis of Surface Wave (MASW) Method utilizes the dispersive nature of Surface wave (Rayleigh wave) and invert it as Shear Wave velocity profile (Vs) with depth.

If you use 48-channel streamer at 1m seperation as receiver and Peg-40 hammer as source in acquisition, the resulted Vs profile after processing and inversion gives the detail approximately upto 25m-30m.

If there is a cavity, liquifacted area or any weak zone in underground, it will be indicated by very low shear wave velocity (less than 200-250m/sec) in Vs profile. Stiffer ground shows high shear wave velocity.

What do you mean by surface holes?

If there is very Low shear wave velocity near the top of ground level (1m-5m) it is mainly effect of Loose sand/gravel.

I mean the holes about 2*3m size Pranjal Maurya Matthew Mabey

Hi,

About the detection of geological anomalies, like cavities and may be surface hole with the surface wave, (if I understand what are the surface holes) we have developped in 2004 a specific processing based on signal and statistical analyses. You will find some information in published articles.

From my experiment, I consider that it is extremely difficult to detect cavities by using a classical processing such as MASW: dispersive curve picked, numerical inversion ...

One of the reason is that today, all the numerical model we can find, does not take into account the effects of a cavities on the dispersive pattern of the surface wave (Rayleigh, Love, ...).

Rgds

Edouard Mouton

Hi

Thanks about your answer but it doesnt helpe me. would you please if you know any paper or special site about it introduce to me.

I do not know any site about this but you will find two papers about the analyses we do on my profile. The processing is called DCOS and we present processing and results obtained on railways

Edouard Mouton

thanks a lot dear friend

You are welcome

Geological anomalies localisation using surface waves is a part of our activities since 2004. So we have some experiments with it.

Have a good read.

Dear Ehsan,

To find the geophysical response of an underground cavity using MASW, you need to do 2D MASW surveys to generate 2D cross-section of shear wave velocity-depth profile for the investigated site. The cavity should have lower wave velocity comparing with the surrounding environment and would appear as low wave-velocity anomaly on the 2D cross-section, maybe you need another and different geophysical data set (like ERT data) to confirm and constrain your findings.

Thanks dear. would you please introduce to me an article which you know? Raad Eissa

Hi,

I used the method in PhD for site characterization (i.e. to determine shear wave velocity-depth profile) but for sure you can find some studies online using MASW for near surface cavities, try with the following link ,

Article Efficiency of MASW in detecting near-surface cavities

From my experiment, I consider that it is not easy to detect cavities by using MASW Data Only, I suggest using the ERT survey with MASW.

Dear Ehsan Sharokhi,

This the interesting and challengeable subject as I am working on it right now.

Basically, it is possible to identify the subsurface cavity in shallow depth but everything is complicated in the field test. I suggest you to use another method beside the classical MASW.

Regards

Also, I agree with my good friend Edouard Mouton , Somehow it is extremely difficult to detect cavities by using a classical MASW especially by using velocity spectrum, dispersion curve or inversion…

It could be mentioned that the considerable effect of cavity can be identified in the wave field domain by using filtering method and using different methods.

Dear Ahmed,

I agree with you, it is better to detect cavity by ERT (or GPR) method and comparing with MASW method.