Saturday, 20 October 2018

Dead Sea Sinkholes

New Theory for Sinkholes

It was thought that the numerous sinkholes round the Dead Sea were caused by the presence of a salt layer. As the salt was dissolved away by run-off, cavities would form and sinkholes would ensue.

This idea was soon abandoned when no salt was found! Geophysics came to the rescue. Using a "wheelbarrow-mounted vibrating source" - this I would like to see! - a shear wave reflection image was obtained of an alluvial fan. This showed the composition and layering of the fan to a depth of 200 metres. No salt was found but some layers reflected seismic waves very poorly. It was suggested that sand had been washed away from the layers so, instead of forming compact layers, they formed weakened layers of gravel and boulders. These eventually give way and form a sinkhole. 

You can read all about it HERE.

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