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SUMMARY:Challenges in constraining and understanding Strombolian (and Hawa
 iian) volcanism - Bruce Houghton\, University of Hawaii
DTSTART:20131008T153000Z
DTEND:20131008T163000Z
UID:TALK46776@talks.cam.ac.uk
CONTACT:John Maclennan
DESCRIPTION:Activity at Stromboli is exceptionally well characterized on t
 ime scales from milliseconds to millennia but it remains a challenge to id
 entify what portion of that activity should be defined as “Strombolian
 ’ in the strict sense of naming an eruption style\, in a fashion that is
  useful at other volcanoes. Here I look at delineating the limits of ‘St
 rombolian style’\, particularly in the context of demarcation from Hawai
 ian fountaining eruptions. That demarcation has generally been articulated
  in terms of transient versus sustained activity linked to mechanical deco
 upling versus partial coupling of exsolved volatiles. \nPlotting basaltic 
 activity as an erupted mass-duration plot reveals some of the issues. Indi
 vidual ‘normal’ Strombolian explosions occupy the short duration\, sma
 ll volume rate corner of such a plot\, very clearly distinguished from hig
 h Hawaiian fountains that have durations that are 3 to 5 orders of magnitu
 de longer and mass discharge rates that are 10 to 100 times larger. Howeve
 r the spectrum of activity called names  such as ‘low fountains’\, ‘
 gas pistoning’ and ‘paroxysms’ fills much of the area between these 
 extremes.  \nFinally\, while Hawaiian fountains are sustained for hours to
  days\, they are seldom steady\, and new high-speed imagery shows that eve
 n normal Strombolian explosions are pulsatory in nature. The implication i
 s that typical Strombolian explosions are not compatible with simple slugs
  (Taylor bubbles) and that typical Hawaiian fountains are not  simple exam
 ples of  either purely coupled bubbly flow or annular flow.
LOCATION:Harker 1 seminar room\, Department of Earth Sciences
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