H₂ generation by reaction between H₂O and crushed rock: An experimental study on H₂ degassing from the active fault zone

Granite and quartz were crushed under moist conditions in the temperature range of 25–270°C, in order to obtain the information on the mechanism operative for H 2 degassing along active faults. It was found that the amounts of H 2 gas released by crushing granite and quartz increased with temperature up to around 200°C and then decreased suddenly. The results indicate that H 2 gas is generated by a chemical reaction between water and such radicals as Si · and Si—O · formed on the fresh surfaces when the Si—O—Si bonds are destroyed by crushing and that the existence of a maximum for amount of H 2 gas is due to the decrease of the lifetime of Si—O · radical at the temperature higher than about 200°C. The results lend credence to the possibility that H 2 gas is generated in the temperature range of 25–270°C along the active fault through the reaction between groundwater and the fresh surfaces of underground rocks formed by the fault movements.