MEASUREMENTS OF ICE DEFORMATION AT THE CONFLUENCE AREA OF UNTERAARGLETSCHER, BERNESE ALPS, SWITZERLAND

An experimental study of ice deformation at the confluence area of Unt eraargletscher, Bernese Alps, Switzerland, has been carried out. Surfa ce velocities were measured by repeatedly surveying stakes and with th e use of remote-sensing methods. The variation of the vertical strain rates with depth was measured in boreholes, The confluence center line is subjected to longitudinal horizontal extension, which is exceeded in magnitude by a concomitant transverse compression. Vertical strain rates change from positive (extension) at the surface to negative (com pression) in the lowest layers of the glacier.