Graph of amount of sulfur dioxide gas released from Kīlauea's summi...
This graph shows the amount of SO2 released in millions of metric tons per year from Kīlauea Volcano's summit (black bars) and East Rift Zone (red bars) between 1979 and 2016. Kīlauea Volcano's gas emissions increased in 1983 with the onset of the East Rift Zone eruption at Pu‘u ‘Ō‘ō (blue arrow). Another large increase occurred in 2008, when the summit eruption began (green arrow). Pu‘u ‘Ō‘ō was the main source of gas release from 1979-2007, but since 2008, Kīlauea Volcano's summit vent in Halema‘uma‘u Crater has been the dominant gas source.