Researchers collected water samples at 11 sites surrounding the 2016 Kumamoto earthquake. They used a submersible pump to collect water from depths of 280 to 1,300 meters. Photo by Yuji Sano/University of Tokyo

TOKYO, Nov. 29 (UPI) -- Scientists in Japan have discovered a correlation between groundwater helium and earthquakes.

Analysis of groundwater samples suggests crustal stress triggers the release of a helium isotope, helium-4. Researchers collected deep-lying water samples near the epicenter of the 2016 Kumamoto earthquakes, when a 7.3-magnitude main shock killed at least 35 people. Scientists collected the water just 11 days after the quake struck. Their measurements revealed an significant uptick in helium-4 levels compared to readings performed in 2010.


"After careful analysis and calculations, we concluded that the levels of helium-4 had increased in samples that were collected near the epicenter due to the gas released by the rock fractures," Yuji Sano, a professor at the University of Tokyo's Atmosphere Ocean Research Institute, said in a news release.

During lab tests using rocks collected from the Kumamoto epicenter, researchers detailed the release of helium-4 during stress exertion. They confirmed rocks close to the epicenter leached higher amounts of helium-4 than rocks collected from farther away.

Scientists shared their findings in a new paper, published this week in the journal Scientific Reports. The authors hope their research will lead to a groundwater analysis model that can predict an earthquake before it strikes.

"More studies should be conducted to verify our correlation in other earthquake areas," said Sano. "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."