Manchester Applied Mathematics and Numerical Analysis Seminars Winter 1999/2000

December 1, 1999, 4.00 pm

Lecture Theatre OF/B9 Oddfellows Hall (Material Science)

Breaking the seal at Grímsvötn -- subglacial eruptions and floods.

Dr. Andrew Fowler, OCIAM (Oxford Centre for Industrial and Applied Mathematics)

Of several problems associated with theoretical explanations of the jökulhlaups which emerge from the outlet glacier Skeidaràrjökull of the ice cap Vatnajökull in South-East Iceland, the mechanism of flood initiation is one that has hitherto defied explanation. We provide such an explanation based on a careful analysis of the classical Nye-Röthlisberger model, and show that this theory can explain why the seal is broken when the lake level at Grìmsvötn is still some 60 metres below flotation level. In addition, we are able to explain why the jökulhlaup following the 1996 eruption did not occur until flotation level was achieved, and we also show how the cyclicity and magnitude of jökulhlaups can be explained within this theory.

For further info contact either Matthias Heil (mheil@ma.man.ac.uk), Mark Muldoon (M.Muldoon@umist.ac.uk)or the seminar secretary (Tel. 0161 275 5800).