Abstract
In order to examine if the emission of hydrogen shows any correlation with movements of an active fault, we have measured the concentration of hydrogen in soil gas accumulated in holes along the Negoro fault, the Median Tectonic Line. Measurements were made at a newly formed outcrop at Bodai Pass, Wakayama, Japan. Significantly high H2 concentrations were observed for almost all measuring sites located either on or near the fault. The highest H2 concentration was 7600ppm, which is about 15, 000 times as high as that of the atmosphere. In order to obtain basic knowledge on the H2 emission through the Negoro fault, changes in H2 concentration of soil gas with time were measured intermittently at two measuring sites on the fault from the time of the initiation of storing soil gas to that of 30hrs later.
Areal distribution of sites with high concentration of H2 and temporal variations in H2 concentration in soil gas suggest that the observed H2 emission is clearly correlated with presence of the fault.
