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Rock glaciers Gruben, Muragl and Murtel, Switzerland: Area-wide flow fields

Entry ID: ggd293

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Summary

Abstract: Besides their thermal and mechanical properties, rock glaciers are essentially defined by their kinematics. Knowledge of the permafrost flow field provides important information about the origin, morphology, development, dynamics and internal structure of creeping mountain permafrost. Monitoring permafrost behavior helps detecting climate signals. Aerial photogrammetry was used for determining ... digital terrain models (DTM) with high resolution. The differences of multitemporal DTMs of a rock glacier provide the vertical changes of the permafrost surface. Horizontal surface displacements were obtained by simultaneously comparing two aerial photographs taken at different times and from different positions (Kaeaeb 1996a,b; Kaeaeb et al.1998). Repeated overridings by the nearby glacier affected the upper part of the Gruben rock glacier, Wallis. Compared to the lower, periglacial part of the rock glacier the higher surface lowering rates of the debris-covered dead ice remains indicate the dead ice being out of equilibrium. Due to different internal structure and different slopes, horizontal surface velocities show different creep directions as well as different creep rates. The rock glacier advances by about 12 cm/a. A 25-year time series of photogrammetrical monitoring (1970-1995) documents the temporal variations of surface kinematics of the rock glacier (Kaeaeb et al. 1998a). Surface kinematics of Muragl rock glacier (Upper Engadin) over the period from 1981 to 1994 reveal this rock glacier to be a complex system of several individual streams. Changes in elevation show a pattern of zones of surface heave and subsidence in the range of +- 10 cm/a. The rock glacier advances by about 5 cm/a (Kaeaeb 1998). The velocity field 1987-1996 at the surface of Murtel rock glacier, Upper Engadin, points to two dynamically different parts of the creeping permafrost-- (1) high activity and transverse ridges in the inner part and (2) lower activity at the left and right margins. The ridges are advected down stream with a velocity approximately equal to the surface velocity. Stream lines can be interpolated from the surface velocity field. The curvature of the isochrones on Murtel rock glacier is similar to the curvature of the transverse ridges, which suggests slow changes in the flow field (Kaeaeb 1998, Kaeaeb et al. 1998b). These data are presented on the CAPS Version 1.0 CD-ROM, June 1998.

Geographic Coverage

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Spatial coordinates

N: 46.51

S: 46.17

E: 9.93

W: 7.96

Temporal Coverage

Start Date: 1970-01-01

Stop Date: 1994-12-31

Location Keywords

CONTINENT > EUROPE > WESTERN EUROPE > SWITZERLAND > SAAS VALLEY, VALAIS ALPS; UPPER ENGADINE, SWITZERLAND

Science Keywords

CRYOSPHERE > FROZEN GROUND > PERMAFROST > MOUNTAIN PERMAFROST

CRYOSPHERE > FROZEN GROUND > ROCK GLACIERS

ISO Topic Category

GEOSCIENTIFIC INFORMATION

INLAND WATERS

Ancillary Keywords

Permafrost Properties

Remote Sensing

Rock Glaciers

Slope Processes

Data Center

National Snow and Ice Data Center

Data Center URL: http://nsidc.org

Data Center Personnel
Name: NSIDC USER SERVICES Phone: +1 (303) 492-6199 Fax: +1 (303) 492-2468 Email: nsidc at nsidc.org Contact Address: National Snow and Ice Data Center CIRES, 449 UCB University of Colorado City: Boulder Province or State: CO Postal Code: 80309-0449 Country: USA

World Data Center for Glaciology, Boulder

Data Center URL: http://nsidc.org/wdc/

Data Center Personnel
Name: NSIDC USER SERVICES Phone: +1 (303) 492-6199 Fax: +1 (303) 492-2468 Email: nsidc at nsidc.org Contact Address: National Snow and Ice Data Center CIRES, 449 UCB University of Colorado City: Boulder Province or State: CO Postal Code: 80309-0449 Country: USA

Frozen Ground Data Center

Data Center URL: http://nsidc.org/fgdc/

Data Center Personnel
Name: NSIDC FGDC USER SERVICES Phone: +1 (303) 492-6199 Fax: +1 (303) 492-2468 Email: nsidc at nsidc.org Contact Address: National Snow and Ice Data Center CIRES, 449 UCB University of Colorado City: Boulder Province or State: CO Postal Code: 80309-0449 Country: USA