HE-3 AND METHANE IN SAKURAJIMA CALDERA, KAGOSHIMA BAY, JAPAN

Volcanic gases from the submerged caldera of Sakurajima Volcano are characterized by He-3/He-4 = 6.1R(A), CH4/He-3 almost-equal-to 10(9), and a ratio of excess SIGMACO2 to He-3 of 140 x 10(9). Helium in the Kagoshima Bay waters is a mixture of volcanic helium and atmospheric-solubility helium in surface waters, and provides a strong signature for seawater injected into the protocaldera by flow through the volcanic edifice, the probable source of the warm deep water that replaces the colder, more saline deep water of the North Basin in November.