A team of researchers with members from Iceland, Sweden and Saudi Arabia has found evidence of chemical changes to underground water prior to two different earthquakes that occurred in 2012 and 2013 in Iceland. In their paper published in the scientific journal Nature Geoscience, they…
A team of researchers with members from Iceland, Sweden and Saudi Arabia has found evidence of chemical changes to underground water prior to two different earthquakes that occurred in 2012 and 2013 in Iceland. In their paper published in the scientific journal Nature Geoscience, they acknowledge their findings do not guarantee total accuracy, but they believe the results found are far-reaching.
Scientists have suspected that ground water experiences changes prior to an earthquake – bottled water from a local well was tested before and after the Kobe quake in 1995, and researchers found differences, and similar results were found with well water before and after a quake in China in 1976 – but both tests suffered from a lack of data, and because both were single incidents it was difficult to state with confidence if the water change and earthquakes were truly related.
Groundwater chemistry has been observed to change before earthquakes and is proposed as a precursor signal. Changes in seismic wave velocities, water levels in boreholes, micro-seismicity and shear wave splitting are also thought to precede earthquakes. Precursor activity has been attributed to expansion of mantle plumes.
Hydrogen (water) in the mantle was incorporated in the interior during the formation of the Earth. The incorporated hydrogen was hardly possible to concentrate locally inside the Earth considering its high mobility and high reactivity. The hydrogen could be distributed homogeneously over the mantle and the core by the subsequent physical and chemical processes.
Minerals such as olivines, silicate, magnesium, and pyroxene just prior to earthquakes were found in the tested water – and are the same minerals found in mantle plumes and calderas.
The study suggests the changes in water minerals were caused by a kind of crustal melting and mixing associated with stress build-up before each earthquake, which caused different groundwater components to mix. We infer that similar processes may be active elsewhere, and that groundwater chemistry is a promising target for future studies on the predictability of earthquakes.