Furtwängler Glacier margin collapse - January 2003

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Ascending to Kibo's summit on 24 January of 2003, a group of climbers with Thomson Safaris witnessed an unusual event. Hearing a rumble behind them, the group turned to watch a portion of the Furtwängler Glacier margin crumble and "spill out on the crater floor" (Vincent Keipper, 2004 personal communication). They saw "slush and water flowing out" then cross the trail and "pour down" the Western Breach. Luckily, Keipper had his camera handy:

Jan. 2003; V. Keipper photo

Additional images, and a brief discussion of the event, were published in the October 2003 issue of National Geographic Adventure magazine, available here. Considerable speculation followed as to the causal mechanism of this collapse, but no direct evidence was available. However, our Northern Icefield weather station measurements are instructive. Following several episodes of snowfall between mid-November 2002 and about January 2nd, the balance of the month was dry. Solar radiation receipt was high, reaching 1,100 W m^-2 on most days, and daily air temperature maxima were reaching their highest values of the year, at nearly -2°C. Most significantly, during the day and night preceeding the collapse, a pronounced lowering of the snowpack (relative to other days during January) indicates accelerated ablation. Was some of this ablation due to melting?

The Furtwängler Glacier surface in September 2004 is shown below, illustrating both accumulation of supraglacial meltwater (at left) and evidence of prior accumulation. We do not know when drainage of meltwater from the right-hand "pond" occurred, but probably more recently than the Jan. 2003 event. Nonetheless, we believe that the mechanism and meltwater origins are similar: during episodes of surface melting, water accumulates until hydrostatic pressure overcomes the confining strength of the vertical walls. Failure occurs suddenly, and the meltwater rapidly drains; camping next to this glacier is not recommended!

The other image below (at right) shows the same Furtwängler margin in September 2004; a red rectangle encloses the same group of rocks shown in the top image. In comparing the two images, also note the position - relative to the ice surface - of the dark strata indicated by the ^ symbol. This apparent ablation is confirmed by our measurements elsewhere on the glacier surface.

Sep. 2004; D. Hardy photo Sep. 2004; D. Hardy photo