Figure 6. Averaged SO₂ emissions from Kilauea's east rift zone as measured by tripod-based COSPEC from 1984 through 1997. The black vertical bars represent the standard deviation of all measurements on a single day. Emission rates for 1984-1985 (filled boxes) generally characterize degassing at Pu‘u ‘Ō‘ō during the repose periods between fountaining events. However, eruption episode (EE) 23 data were collected during a fountaining event. Eruption episode 28 data were collected several hours after the end of a fountaining event, and eruption episode 19 and 35A measurements were made during other non-fountaining activity. Measurements of Pu‘u ‘Ō‘ō emissions made during eruption episode 48 (filled circles) were discontinued in late 1991. The hollow circles, stars, and filled triangles denote emission-rate data from various instrument sites used during 1995-1997 and span periods of eruptive pause, eruptive surge, and varying levels of vent activity.