Implications for eruptive processes as indicated by sulfur dioxide emissions from Kilauea Volcano, Hawai'i, 1979-1997
Kı̄lauea Volcano, Hawai‘i, currently hosts the longest running SO 2 emission-rate data set on the planet, starting with initial surveys done in 1975 by Stoiber and his colleagues. The 17.5-year record of summit emissions, starting in 1979, shows the effects of summit and east rift eruptive processes, which define seven distinctly different periods of SO 2 release. Summit emissions jumped nearly 40% with the onset (3 January 1983) of the Pu`u `Ō`ō-Kūpaianaha eruption on the east rift zone (ERZ). Summit SO 2 emissions from Kı̄lauea showed a strong positive correlation with short-period, shallow, caldera events, rather than with long-period seismicity as in more silicious systems. This correlation suggests a maturation process in the summit magma-transport system from 1986 through 1993. During a steady-state throughput-equilibrium interval of the summit magma reservoir, integration of summit-caldera and ERZ SO 2 emissions reveals an undegassed volume rate of effusion of 2.1×10 5 m 3 /d. This value corroborates the volume-rate determined by geophysical methods, demonstrating that, for Kı̄lauea, SO 2 emission rates can be used to monitor effusion rate, supporting and supplementing other, more established geophysical methods. For the 17.5 years of continuous emission rate records at Kı̄lauea, the volcano has released 9.7×10 6 t (metric tonnes) of SO 2 , 1.7×10 6 t from the summit and 8.0×10 6 t from the east rift zone. On an annual basis, the average SO 2 release from Kı̄lauea is 4.6×10 5 t/y, compared to the global annual volcanic emission rate of 1.2×10 7 t/y.