Signs in groundwater chemistry make help scientists predict earthquakes

Scientists searching for a way to predict earthquakes have uncovered the most promising lead yet, after uncovering tell-tale chemical spikes in groundwater up to six months before tremors struck.

Major earthquakes can kill hundreds of thousands of people, as in Haiti in 2010, but they are the only natural disaster that cannot currently be forecast.

Some experts think a useful prediction of time, place and magnitude may be an impossible dream. Previously, scientists have examined radon gas leaks, heat maps and even unusual animal behaviour as possible earthquake indicators, without success.

But now geologists taking weekly measurements of groundwater chemistry in northern Iceland over five years have discovered big shifts four to six months before two separate earthquakes in 2012 and 2013. The quakes were both significant in size - over magnitude five - and 75km from the sampling site.

"This does not mean we can predict earthquakes yet, but at the least we have shown something happens before earthquakes," said Professor Alasdair Skelton, of Stockholm University, who led the research published in Nature Geoscience.

"That is tantalising, as it means something is happening to the rocks before the earthquakes. We are highlighting groundwater chemistry as a promising target for future earthquake prediction studies."

The fact the chemical spikes were identified before two different earthquakes is significant, said Skelton, because it indicates they are not a mere coincidence. He said the chances of that were a 100,000 to one.