Strombolian explosive styles and source conditions: Insights from thermal (FLIR) video
Document Type
Article
Publication Date
6-2007
Department
Department of Geological and Mining Engineering and Sciences
Abstract
Forward Looking Infrared Radiometer (FLIR) cameras offer a unique view of explosive volcanism by providing an image of calibrated temperatures. In this study, 344 eruptive events at Stromboli volcano, Italy, were imaged in 2001-2004 with a FLIR camera operating at up to 30 Hz. The FLIR was effective at revealing both ash plumes and coarse ballistic scoria, and a wide range of eruption styles was recorded. Eruptions at Stromboli can generally be classified into two groups: Type 1 eruptions, which are dominated by coarse ballistic particles, and Type 2 eruptions, which consist of an optically-thick, ash-rich plume, with (Type 2a) or without (Type 2b) large numbers of ballistic particles. Furthermore, Type 2a plumes exhibited gas thrust velocities (> 15 m s-1) while Type 2b plumes were limited to buoyant velocities ( < 15 m s-1) above the crater rim. A given vent would normally maintain a particular gross eruption style (Type 1 vs. 2) for days to weeks, indicating stability of the uppermost conduit on these timescales. Velocities at the crater rim had a range of 3-101 m s-1, with an overall mean value of 24 m s-1. Mean crater rim velocities by eruption style were: Type 1=34 m s-1, Type 2a=31 m s-1, Type 2b=7 m s-1. Eruption durations had a range of 6-41 s, with a mean of 15 s, similar among eruption styles. The ash in Type 2 eruptions originates from either backfilled material (crater wall slumping or ejecta rollback) or rheological changes in the uppermost magma column. Type 2a and 2b behaviors are shown to be a function of the overpressure of the bursting slug. In general, our imaging data support a broadening of the current paradigm for strombolian behavior, incorporating an uppermost conduit that can be more variable than is commonly considered.
Publication Title
Bulletin of Volcanology
Recommended Citation
Patrick, M.,
Harris, A.,
Ripepe, M.,
Dehn, J.,
Rothery, D.,
&
Calvari, S.
(2007).
Strombolian explosive styles and source conditions: Insights from thermal (FLIR) video.
Bulletin of Volcanology,
69(7), 769-784.
http://doi.org/10.1007/s00445-006-0107-0
Retrieved from: https://digitalcommons.mtu.edu/michigantech-p/4743