The chemistry of groundwater changed prior to two consecutive earthquakes in northern Iceland, reports a study published online this week in Nature Geoscience. The findings imply that measurements of groundwater chemistry might one day help with monitoring seismic hazards.

Alasdair Skelton and colleagues sampled groundwater from a flowing well in northern Iceland on a weekly basis for five years. They found that the chemistry of the groundwater changed about four to six months before each of two earthquakes that occurred in October 2012 and April 2013. The authors suggest that as stresses built up in Earth’s crust prior to each quake, the rocks expanded causing elements such as calcium and sodium to be dissolved in the groundwater, resulting in the mixing of previously distinct groundwater components. They do not claim that this method can predict earthquakes, but the study highlights the potential for using regular and long-term monitoring of groundwater chemistry in seismically active areas to identify heightened earthquake risk.

In an accompanying News and Views article, Steven Ingebritsen and Michael Manga write “The potential for predicting earthquakes has great importance, and great claims require strong evidence. The observations by Skelton and colleagues are sufficiently compelling to prompt further investigation.”