The emission of occluded gas from rocks as a function of stress: Its possible use as a tool for predicting earthquakes

Occluded gases were studied from fifteen types of rock, including igneous, metamorphic and sedimentary. The specimens were stressed to a crushing failure at room temperature under a vacuum of about 10 −9 torr. The more abundant gases were H 2 , CH 4 , H 2 O, N 2 CO, O 2 and CO 2 . However, each rock released gas with a characteristic composition. The volume of gas released was a variable function of stress above a threshold value. The greatest rate of emission occurred over the latter 20% of the rock's ability to withstand stress. Analyses of stress‐released occluded gases (excluding water), released as a function of stress, are given for a granodiorite and a gneiss. Volumes (STP)of most gases observed prior to and upon failure of the rocks are equivalent to several hundred liters each per ton of rock. Stress‐induced emission of a widely distributed, highly mobile gas such as H 2 could serve as an useful indicator of a critical stress build‐up in the earth's crust.