Successive Holocene rock avalanches at Lake Coleridge, Canterbury, New Zealand

Lee, Jenny; Davies, Tim; Bell, David

doi:10.1007/s10346-009-0163-6

Cited by 9 publications

(4 citation statements)

References 11 publications

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“…Multiple recurrences of catastrophic, long-runout landslides are not uncommon and have also been described from other regions (Aa et al, 2007;Bisci et al, 1996;Lee et al, 2009;Ocakoglu et al, 2009). Some of these mass movements are periodically accelerated by earthquakes (Ocakoglu et al, 2009).…”

Section: Implications For Landslide Chronologymentioning

confidence: 94%

Late-Holocene evolution of a floodplain impounded by the Smrdutá landslide, Carpathian Mountains (Czech Republic)

et al. 2012

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Landslides affecting narrow mountainous valleys might significantly determine sedimentation dynamics of floodplains. We present here a detailed study of the sedimentary archive within a landslide-controlled impounded floodplain (Smrdutá site, Czech Flysch Carpathians) using geochronological ( 14 C and 137 Cs), sedimentological and pollen evidence. A sedimentary sequence deposited above the landslide dam points to three highly discontinuous and instantaneous depositional events dated to 4.6 and 2.0 cal. ka BP, whereas the last cycle started approximately in the 17-18th centuries and has continued to recent times. Such sedimentary pulses characterized by the duration of several decades to a few centuries originated as a consequence of the blockage and/or reduction of the valley floor width by successive long-runout landslides from a slope formed by tectonically and lithologically anisotropic flysch bedrock. Stages of mass movement activity revealed by the Smrdutá landslide correlate well with major humid late-Holocene oscillations suggesting its high sensitivity to century-scale climatic deteriorations. The character of lithological units forming individual sedimentary pulses, erosional hiatuses and sedimentary traces caused by the July 1997 extreme flood indicate a decisive role of large flood events during accretion and erosion of the floodplainimpounded section.

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Section: Implications For Landslide Chronologymentioning

confidence: 94%

Late-Holocene evolution of a floodplain impounded by the Smrdutá landslide, Carpathian Mountains (Czech Republic)

et al. 2012

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“…In the laboratory, we used well-sorted medium greywacke river sand to represent normal (englacially derived) supraglacial debris; like normal supraglacial debris the material is highly permeable (Drewry, 1986) and has relatively low thermal inertia. To represent rock-avalanche debris we took material from below the carapace of the Coleridge rock-avalanche deposit, New Zealand (Lee and others, 2009). This material is typical of rock-avalanche debris: very widely (fractally) graded, with low permeability, and with coarser fragments embedded in pulverized matrix and containing abundant ‘powder’ (Hewitt and others, 2008).…”

Section: Supraglacial Debrismentioning

confidence: 99%

Effects of debris on ice-surface melting rates: an experimental study

et al. 2010

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ABSTRACT. Here we report a laboratory study of the effects of debris thickness, diurnally cyclic radiation and rainfall on melt rates beneath rock-avalanche debris and sand (representing typical highly permeable supraglacial debris). Under continuous, steady-state radiation, sand cover >50 mm thick delays the onset of ice-surface melting by >12 hours, but subsequent melting matches melt rates of a bare ice surface. Only when diurnal cycles of radiation are imposed does the debris reduce the longterm rate of ice melt beneath it. This is because debris >50 mm thick never reaches a steady-state heat flux, and heat acquired during the light part of the cycle is partially dissipated to the atmosphere during the nocturnal part of the cycle, thereby continuously reducing total heat flux to the ice surface underneath. The thicker the debris, the greater this effect. Rain advects heat from high-permeability supraglacial debris to the ice surface, thereby increasing ablation where thin, highly porous material covers the ice. In contrast, low-permeability rock-avalanche material slows water percolation, and heat transfer through the debris can cease when interstitial water freezes during the cold/night part of the cycle. This frozen interstitial water blocks heat advection to the ice-debris contact during the warm/day part of the cycle, thereby reducing overall ablation. The presence of metre-deep rock-avalanche debris over much of the ablation zone of a glacier can significantly affect the mass balance, and thus the motion, of a glacier. The length and thermal intensity of the diurnal cycle are important controls on ablation, and thus both geographical location and altitude significantly affect the impact of debris on glacial melting rates; the effect of debris cover is magnified at high altitude and in lower latitudes.

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“…This is partly because of the limited extent of present-day glaciers and also, significantly, because supraglacial rock avalanche deposits are rapidly reworked by glaciers and deposited as moraines whose potential rock-avalanche origins have rarely been considered in the past. By contrast, a rock avalanche depositing into a glacier-free river valley, though progressively removed by river erosion, often leaves longterm recognisable traces of its initial extent in the form of remnant large angular boulders and vestigial high terraces (Chevalier et al, 2009;Lee et al, 2009). Thus, more likely that the frequency of supraglacial rock avalanches and, hence, their significance to glacier dynamics and behaviour have in the past been underestimated.…”

Section: Introductionmentioning

confidence: 99%