Abstract
In order to verify the possibility of submarine hot spring discharges along the coast of Beppu Bay, we used a radon (Rn) towing survey method using a small vessel, which has been frequently used in recent years to survey coastal submarine groundwater discharge (SGD). Analysis of the data using the "Rn concentration and salinity mixing diagram," which includes data from hot springs, groundwater (springs and well water), and river water in the land area along the coast, showed that there were four areas with a high mixing ratio of groundwater. As a result of investigating the relationship between these four locations and estimated hot spring flow paths and subsurface structure of the terrestrial area, and the relation between radon concentration and water temperature in these four locations, it was shown that two of the locations may be submarine hot spring discharge areas.
