The Guardian reports, "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 … are the only natural disaster that cannot currently be forecast. …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 47 miles 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 Prof Alasdair Skelton, at Stockholm University, Sweden, who led the research published in Nature Geoscience.

"…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 hundred-thousand to one. …The chemical changes are thought to occur as stress builds on the rocks before the earthquakes and creates small fractures which connect up different acquifers allowing them to mix.

"...Professor Ian Main, at the University of Edinburgh, Scotland, said caution was needed and the influence of other possible factors, such as shifting magma below the ground, needed to be assessed… “Most geophysical and geochemical signals fluctuate all the time, so it is virtually inevitable that some areas will have signals coincident with earthquakes.”"

Deb Gaber