You are not permitted to download, save or email this image. Visit image gallery to purchase the image.
''How big an issue it is [seismic danger] I can't tell you,'' he said.
Dr Lindstrom, of the Stockholm International Water Institute, in Sweden, spoke about pressures on water use from population growth, agriculture, energy production, and the increasing need for regional co-operation over water usage.
Hydraulic fracturing, or fracking, had enabled a ''revolution'' in shale gas production in the United States. This had major geopolitical implications as energy production moved to different parts of the world.
Fracking is an energy extraction process using up to 99.5% water mixed with chemicals injected into rocks in order to release gas.
It did not use as much water as some other industrial processes, but used fracking water could not be reused for other purposes, except further fracking, he said.
Exactly how much water is consumed by fracking is unknown because there was no standardised way of measuring water use. Evidence of adverse health effects, including cancer, caused by groundwater pollution from fracking was also ''circumstantial'', and companies were able to deny links.
Shale gas companies were strongly protected in law in the US, prohibiting revealing the composition of chemicals used in the fracking process.