Mair, D. and Willis, I. and Fischer, U. H. and Hubbard, B. and Nienow, P. and Hubbard, A. (2003)

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

Article
Cite key
Mair2003
Language
en
Journal
Journal of Glaciology
Volume
49
Number
167
Pages
555-567
URL
http://docserver.ingentaconnect.com/deliver/connect/igsoc/00221430/v49n167/s10.pdf?expires=1346078811&id=70203388&titleid=6497&accname=Universite+de+Lausanne&checksum=DA557C8413EB2AC6672E73005016226B
Description
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.