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Exploring the explosive-effusive transition using permanent ultraviolet cameras
- Source :
- Journal of Geophysical Research: Solid Earth. 122:4377-4394
- Publication Year :
- 2017
- Publisher :
- American Geophysical Union (AGU), 2017.
-
Abstract
- Understanding the mechanisms that cause effusive eruptions is the key to mitigating their associated hazard. Here, we combine results from permanent ultra-violet (UV) cameras, and from other geophysical observations (seismic very long period, thermal, and infrasonic activity), to characterize volcanic SO2 flux regime in the period prior, during, and after Stromboli's August-November 2014 effusive eruption. We show that, in the two months prior to effusion onset, the SO2 flux levels are two times average level. We explain this anomalously high SO2 regime as primarily determined by venting of rapidly rising, pressurized SO2-rich gas pockets, produced by strombolian explosions being more frequent and intense than usual. We develop a procedure to track (and count), in the UV camera record, the SO2 flux pulses produced by individual explosions and puffing activity (active degassing). We find that these SO2 pulses are far more numerous (67 ± 47 events/hour) before the effusion onset than during normal activity (20 ± 15 events/hour). This observation, combined with geophysical evidence, demonstrates an elevated gas bubble supply to the shallow conduits, causing elevated explosive and puffing activity. This increase (≥0.1 m3s-1) in magma transport rate in the north-east feeding conduits finally triggers effusion onset. Active degassing remains elevated also during the effusive phase, supporting the persistence of explosive and puffing activity during the effusive eruption, deep in the volcanic conduit. Our results demonstrate that permanent UV cameras can valuably contribute to monitoring at high sampling frequency gas dynamics and fluxes, thus opening the way to direct comparison with more established geophysical observations.
- Subjects :
- event.disaster_type
geography
geography.geographical_feature_category
010504 meteorology & atmospheric sciences
Explosive material
Ultra violet
Geophysics
010502 geochemistry & geophysics
01 natural sciences
Strombolian eruption
Volcanic Gases
Effusive eruption
Flux (metallurgy)
Volcano
Space and Planetary Science
Geochemistry and Petrology
Magma
Earth and Planetary Sciences (miscellaneous)
event
Petrology
Geology
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 21699313
- Volume :
- 122
- Database :
- OpenAIRE
- Journal :
- Journal of Geophysical Research: Solid Earth
- Accession number :
- edsair.doi...........2ff1b9e4381a6aedd19793011754e519