Author Topic: Detection of caves by seismic analysis ??  (Read 393 times)

Offline Bob Mehew

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Detection of caves by seismic analysis ??
« on: November 30, 2021, 03:48:54 pm »
I recently came across https://www.space.com/mars-subsurface-map-from-insight-wind-sound?fbclid=IwAR2_eh-gWAFu1PTfjJzG-xIAzUlOAbF0YLRJPfGStgLpzjTQt2AwNMusdS0 and thought I wonder how that works.  Looking at the paper gave no details but by going back through the refereces I found https://www.academia.edu/26078683/Frequency_dependent_traveltime_tomography_using_fat_rays_application_to_near_surface_seismic_imaging which seems to give an explanation ('seems' and 'explanation' may be optimistic as I have to admit not understanding most of what is written).  Does anyone know of its possible use (or of a similar technique) to detect caves? 

Offline rm128

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Re: Detection of caves by seismic analysis ??
« Reply #1 on: December 01, 2021, 09:46:43 am »
Hi Bob. Detecting caves using seismic data is actually a very difficult thing to do. To be honest, I don't know if it has been done successfully or not. I know it is an active area of research for various reasons, e.g. to avoid cavities during construction projects. I suspect the most interesting research in this area would involve tunnel detection... particularly across borders (USA-Mexico, Israel-Gaza etc...), but I also suspect that you will struggle to find relevant publications, for obvious reasons. The following link will take you to a Masters Thesis that explains some of the issues:

https://digitalcommons.mtu.edu/cgi/viewcontent.cgi?article=1207&context=etdr

I guess there are different levels of cave detection. At one end of the spectrum, you could no doubt generate a detailed survey, even at significant depth, using the latest techniques from the oil exploration industry (e.g. Full Waveform Inversion, or joint inversion of seismic, gravity and/or resistivity data.) This is possible, but it would involve the collection of a lot of expensive data and significant computational resources. At the other (more realistic) extreme you would simply be looking for some sort of anomaly (probably quite close to the surface) that may or may not be a cave passage.

Offline Andy Farrant

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Re: Detection of caves by seismic analysis ??
« Reply #2 on: December 01, 2021, 11:23:40 am »
There have been numerous studies where seismic methods have been used to identify karst features in the subsurface for the oil industry. These are usually breccia pipes, collapse features and seismic scale hypogene karst features, but identifying individual caves which are usually at the sub-seismic scale is more difficult. There may be scope using shallow passive seismic methods, but as with any geophysical technique, the devil is in the interpretation.

 

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