Groundwater Chemistry May Signal Impending Earthquakes

Identifying environmental variables that can foretell earthquakes is one of the most sought-after goals of the earth sciences. It’s also contentious because some scientists think it can’t be done. New data from an Icelandic monitoring well showing significant changes in groundwater chemistry before two earthquakes may challenge that view. A research team led by Alasdair Skelton of Stockholm University found via inductively coupled plasma optical emission spectroscopy and cavity ring-down spectroscopy that levels of sodium, calcium, silicon, and deuterium increased in the groundwater of a 100-meter-deep artesian well weeks before magnitude 5.5 and 5.6 earthquakes in Iceland (Nat. Geosci. 2014, DOI: 10.1038/ngeo2250). The researchers posit that stress before the quakes dilated Earth’s crust, exposing the groundwater to fresh mineral surfaces and new pathways to mix with previously isolated water reservoirs. Although other researchers say these compositional changes may indicate other quake-inducing geological processes, such as shifting magma flows, they agree with the team’s claim that groundwater chemistry is “a promising target for future earthquake prediction studies.”