Hydrological controls on patterns of surface, internal and basal motion during three "spring events": Haut Glacier d'Arolla, Switzerland

Douglas Watson Fraser Mair, I. Willis, U. H. Fischer, B. Hubbard, P. Nienow, A. Hubbard

Research output: Contribution to journalArticle

68 Citations (Scopus)

Abstract

Three early-melt-season high-velocity events (or "spring events") occurred on Haut Glacier d'Arolla, Switzerland, during the melt seasons of 1998 and 1999. The events involve enhanced glacier velocity during periods of rapidly increasing bulk discharge in the proglacial stream and high subglacial water pressures. However, differences in spatial patterns of surface velocity, internal ice deformation rates, the spatial extent of high subglacial water pressures and in rates of subglacial sediment deformation suggest different hydrological and mechanical controls. The data from two of the events suggest widespread ice-bed decoupling, particularly along a subglacial drainage axis creating the highest rates of basal motion and "plug flow" in the overlying ice. The other event showed evidence of less extensive ice-bed decoupling and sliding along the drainage axis with more mechanical support for ice overburden transferred to areas adjacent to decoupled areas. We suggest that: (1) plug flow may be a common feature on glaciers experiencing locally induced reductions in basal drag; (2) Under certain circumstances, enhanced Surface motion may be due in part to non-locally forced enhanced bed deformation, and (3) subglacial sediment deformation is confined to a depth of the order of centimetres to decimetres.

Original languageEnglish
Pages (from-to)555-567
Number of pages12
JournalJournal of Glaciology
Volume49
Issue number167
Publication statusPublished - 2003

Keywords

  • SUBGLACIAL WATER-PRESSURE
  • HIGH-VELOCITY EVENT
  • DRAINAGE SYSTEM
  • SEASONAL-VARIATIONS
  • ICE DEFORMATION
  • BOREHOLE
  • TILL
  • BED
  • STORGLACIAREN
  • SWEDEN

Cite this

Mair, D. W. F., Willis, I., Fischer, U. H., Hubbard, B., Nienow, P., & Hubbard, A. (2003). Hydrological controls on patterns of surface, internal and basal motion during three "spring events": Haut Glacier d'Arolla, Switzerland. Journal of Glaciology, 49(167), 555-567.