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<\/a>Under unsteady source conditions, plumes are not fed by a constant stream of ash and gas, but by a sequence of ash \"pulses\". The depicted image sequence shows the contours of an analyzed ash pulse during the 2010 Eyjafjallaj\u00f6kull eruption [1]. (Courtesy of M. Rietze [2])<\/p><\/div>Pulsating source behaviours is assessed by the pulse analysis method, which was developed to derive the mass of individual pulses by video analysis and to quantify their contribution to the overall mass flux [1].<\/p>\n
Within MAXI-Plume this tool will be applied in combination with a time-dependent 1D plume model [3] to a number of Icelandic case scenarios (including the eruptions of Gr\u00edmsv\u00f6tn 2004 and 2011).<\/p>\n
<\/a>Based on video analysis and geometrical considerations, the volume, mass and density of individual ash pulses can be reconstructed. With these data and by counting the frequency of ash pulses it is possible to estimate the mass flux. (For details about this principle, please see D\u00fcrig et al. [1]).<\/p><\/div>We hope that this will provide us new insights on the link between fragmentation and eruptive source conditions, on the predictive capabilities of the tested model and on the effects of pulsating source conditions on plume dynamics.<\/p>\n
<\/a>Pulse gun: the three conduits are fired with a temporal delay, simulating a pulsating source.<\/p><\/div>\n
<- back to mass flux<\/a><\/p>\n [1]: D\u00fcrig, T. et al: Mass eruption rates in pulsating eruptions estimated from video analysis of the gas thrust\u2013buoyancy transition \u2013 a case study of the 2010 eruption of Eyjafjallaj\u00f6kull, Iceland. Earth Planets Space 67(1), 180 (2015).<\/a><\/p>\n [2]: www.mrietze.de<\/a><\/p>\n [3]: Woodhouse, M. J., Phillips, J. C. & Hogg A. J. Unsteady turbulent buoyant plumes. J. Fluid Mech., 794, 595-638 (2016)<\/p>\n","protected":false},"excerpt":{"rendered":" Unsteady source conditions Almost all 1D models presume steady flow conditions at the source. Many small to medium-sized explosive eruptions, however, also show stages of pulsating behavior, which could be a potential source of error when applying steady 1D models. … Continue reading References and annotations:<\/h2>\n