Influence of runout-path material on emplacement of the Round Top rock avalanche, New Zealand

Factors influencing the distance a disintegrating rock mass travels as it spreads across the landscape after detaching from a slope include the volume and mechanical properties of the material, local topography and the materials encountered in the runout path. Here we investigate the influence of ru...

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Bibliographic Details
Published in:Earth surface processes and landforms 2010-02, Vol.35 (2), p.190-201
Main Authors: Dufresne, A., Davies, T.R., McSaveney, M.J.
Format: Article
Language:English
Subjects:
Alignment
Avalanches
Bgi / Prodig
Deposits
disintegrating rock mass
Elongation
Geomorphology
Gravel
mobility
morphology
Physical geography
Ridges
Rock
Rock (material)
Round Top rock avalanche
runout path
Slopes
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Summary:Factors influencing the distance a disintegrating rock mass travels as it spreads across the landscape after detaching from a slope include the volume and mechanical properties of the material, local topography and the materials encountered in the runout path. Here we investigate the influence of runout‐path material on the mobility and final morphology of the Round Top rock avalanche deposit, New Zealand. This rock avalanche of mylonitic schist ran out over a planar surface of saturated fluvial gravel. Longitudinal ridges aligned radial to source grade into smaller aligned hummocks and digitate lobes in the distal reach. Soils and river gravels in the runout path are found bulldozed at elongate ridge termini where they formed local obstacles halting avalanche motion at these locations, thus aiding development of prominent elongate ridges on the deposit. Further travel over the disrupted substrate led to avalanche–substrate mixing at the base of the debris mass. Field observations combined with subsurface geophysical investigations and laboratory analogue models illustrate the processes of substrate deformation features at the Round Top rock avalanche. Copyright © 2009 John Wiley & Sons, Ltd.
ISSN:0197-9337
1096-9837
DOI:10.1002/esp.1900