The old adage that being forewarned is being forearmed perhaps never rings as true as in the case of natural disasters like tsunamis, volcanoes and earthquakes. Earlier this year, researchers discovered that it might be possible to predict the fiery eruptions of volcanoes by listening for a period of calm in their normal geologic rumblings. Now, scientists believe they're on to a new prediction method for earthquakes – measuring the amount of helium in the groundwater.

Researchers at the University of Tokyo examined sites near the epicenter of the 7.3-magnitude Kumamoto earthquake that rocked southwestern Japan in April 2016. With a submersible pump lowered into wells descending up to 1,300 m (4,265 ft) into the Earth, the team grabbed groundwater samples 11 days after the earthquake hit. The results of their research have been published today in the journal Scientific Reports.

They found evidence of elevated levels of an isotope known as helium-4 when the samples were compared to those taken in 2010. They posit that the heightened level of the isotope came from its escape into the groundwater when the Earth's crust fractured prior to the quake.

They also determined that the levels of the gas were highest in the groundwater taken closest to the epicenter of the quake, meaning that monitoring for elevated helium-4 levels in groundwater in earthquake-prone areas could one day work as an early warning system pinpointing where an impending earthquake would be most destructive.

"More studies should be conducted to verify our correlation in other earthquake areas," says study lead author Yuji Sano, a professor at the University of Tokyo's Atmosphere Ocean Research Institute. "It is important to make on-site observations in studying earthquakes and other natural phenomena, as this approach provided us with invaluable insight in investigating the Kumamoto earthquake."