Abstract
Since 2004, the satellite-borne Ozone Mapping Instrument (OMI) has observed sulphur dioxide (SO2) plumes during both quiescence and effusive eruptive activity at Soufrière Hills Volcano, Montserrat. On average, OMI detected a SO2 plume 4–6 times more frequently during effusive periods than during quiescence in the 2008–2010 period. The increased ability of OMI to detect SO2 during eruptive periods is mainly due to an increase in plume altitude rather than a higher SO2 emission rate. Three styles of eruptive activity cause thermal lofting of gases (Vulcanian explosions; pyroclastic flows; a hot lava dome) and the resultant plume altitudes are estimated from observations and models. Most lofting plumes from Soufrière Hills are derived from hot domes and pyroclastic flows. Although Vulcanian explosions produced the largest plumes, some produced only negligible SO2 signals detected by OMI. OMI is most valuable for monitoring purposes at this volcano during periods of lava dome growth and during explosive activity.
Highlights
Sulphur dioxide (SO2) has a strong absorption signature in the UV and a low background abundance in the atmosphere, both of which facilitate its measurement in volcanic plumes and make SO2emission rate a valuable volcano monitoring tool (e.g. Oppenheimer et al, 2011; Shinohara, 2008; Edmonds et al, 2003a)
The Differential Optical Absorption Spectrometry (DOAS) record shows that the SO2 emission rate was variable during Phase 4, ranging from 2000 t/day (Fig. 6)
There is no correlation between DOAS SO2 emission rate and the explosive volcanic events, though this could be impacted by the timing of the event (UV spectroscopy is not possible during the night) or due to the ash content of the plume increasing the opacity of the plume (Fig. 6)
Summary
Sulphur dioxide (SO2) has a strong absorption signature in the UV and a low background abundance in the atmosphere, both of which facilitate its measurement in volcanic plumes and make SO2emission rate a valuable volcano monitoring tool (e.g. Oppenheimer et al, 2011; Shinohara, 2008; Edmonds et al, 2003a). Sulphur dioxide (SO2) has a strong absorption signature in the UV and a low background abundance in the atmosphere, both of which facilitate its measurement in volcanic plumes and make SO2. Satellite observations of volcanic SO2 emissions, of lower resolution, complement ground-based spectrometer systems, which may not be effective during ashproducing eruptive events (Christopher et al, 2010) or for measuring vertically-rising plumes. There have been many observations of volcanic SO2 plumes from space-borne instruments. Soufrière Hills volcano has a wellestablished ground-based instrument array along with other monitoring data (seismometers, GPS, tiltmeters, infrasound monitors). This provides an ideal test case to investigate the ground- and satellite-based measurement of SO2 emission at a volcano with a highly variable, but well constrained, activity level
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
