永久冻土

Encyclopédie environnement - permafrost - pergélisol

  永久冻土广泛分布于地球表面,在北半球尤为丰富,随着纬度和海拔的不同,永久冻土的厚度和连续性也不相同。永久冻土主要分为两类:一类是占据阿拉斯加、加拿大和西伯利亚大陆架大片地区的厚层连续性永久冻土;另一类是主要分布在山脉中的薄层不连续、甚至零星散布的永久冻土,在高山地区尤为常见。石冰川是永久冻土中的一种独特类型,对其成因和行为的研究往往特殊,不同于研究所谓传统“真实”的冰川。本文还讨论了气候变化下与山地永久冻土相关的灾害风险。

1. 永久冻土的定义和分布

  永久冻土(英语permafrost,法语pergelisol)的概念于1947年[1]首次提出,此后一直是冰冻圈研究的重要内容。

  永久冻土的定义包括温度和时间两个要素,指地表下至少在一年内温度从未超过0℃的地区。其存在对基岩、地表形态和土壤都有影响。永久冻土中可能含冰也可能没有:在岩石中,含冰量有限,仅能填充其裂缝;而在地表地层中,冰的重要性更为突出,它不仅填充了所有的孔隙(饱和永冻层),而且可以形成薄冰层或冰透镜体,使得地表地层中冰的体积比超过其在岩体中(过饱和永冻层)。

环境百科全书-永久冻土-全球冻土区分布
图1. 图中红色为连续多年冻土区,橙色为不连续或者零星分布的多年冻土区。[©hkeita/shutterstock]

  永久冻土约占地球陆地表面的20%,即2500万平方公里,相当于北半球陆地面积的四分之一。相比之下,大陆上的冰(不包括海冰)仅有1600万平方公里。

  根据永久冻土覆盖总面积的比例,通常会按纬度(或海拔高度)进行区分:

  • 连续永久冻土带(地表面积占比在80%以上),
  • 不连续永久冻土带(地表面积占比在30%到80%),
  • 零散永久冻土(地表面积占比在30%以下),
  • 孤立永久冻土。

  永久冻土主要存在于高纬度地区,而在高海拔山地则也有分布。在阿尔卑斯山脉,海拔约2500米以上地区的北侧是不连续永久冻土的潜在分布区,在3500至4000米以上的地区则是更为连续的永久冻土。根据模型计算,法国阿尔卑斯山永久冻土的面积为1300 km²[2],是冰川面积(约500 km²)的两倍以上。

2. 永久冻土的结构

环境百科全书-永久冻土-永久冻土的典型垂直热剖面
图2. 永久冻土的典型垂直热剖面(含最高和最低温度曲线)及相对应的结构。活动层:温度季节性超过0℃;严格意义上的永冻层:温度严格低于或等于0℃。

  永久冻土的形成、维持和消失与气候密切相关。自然环境的变化和人为干扰会改变永久冻土的分布、温度和厚度,进而引起土壤热状况变化。永久冻土的垂直结构,特别是其含冰量,取决于气候、地形、地质和地貌等条件(图2)。

  典型的永久冻土垂直热剖面图有三个清晰的层次:

  表层。夏季温度会超过0℃,有季节性冻融交替,所以也称为活动层active layer)。严格意义上的永久冻土仅指活动层以下、温度始终保持在0℃以下的地层。北极苔原的泥炭土中活动层可能仅有几十厘米厚,而在阿尔卑斯山脉少冰的岩石地形,活跃层厚度可达3至7米。

  永远不会融化的层是严格意义上的永久冻土。在最高温和最低温曲线(Tmax和Tmin)相交点以下,土层温度没有年际波动。年温度波动的最大土层深度很大程度取决于地层中冰的含量。在富含冰的永久冻土区可能仅有几米深,而在在阿尔卑斯山的岩石区可达20到30米。

  多年冻土下限permafrost base)的深度取决于当地的平均气温和地温梯度,前者决定着冻土层的温度。因此,最深的永久冻土往往存在于最寒冷、最干燥的气候条件(低降雪量减弱了雪的隔热作用)。例如,加拿大最北部和西伯利亚的永久冻土深达数百米;1998年至2010年在阿尔卑斯山的钻探表明,在海拔3000米处,永久冻土的厚度可达100米以上。

  地上与地下气候存在着复杂的相互作用,受到多种因素的影响,这些因素大多对气候变化非常敏感。由于底土和积雪层的导热率低,气温波动的影响通常会随着土层深度的加大而衰减。地表温度变化和永久冻土深度变化之间通常有一个时间差,在永冻层深厚地区(北美、西伯利亚等地),滞后期的时间可达几百到几千年;而在永冻层较薄的地区(如阿尔卑斯山等地区),时间差通常以年或几十年来计算。

3. 永久冻土和高山石冰川

  任何类型的土地都可能受到永久冻土的影响,无论是基岩还是沉积物。

  对于岩性山体,其岩石有或多或少的裂隙,并被冰“胶结”。这里冰只存在于岩石裂缝中,其所占比例有限,在裂隙很少的岩石中甚至几乎为零,但对岩体的稳定性起着重要作用。

  对于地表形态,永久冻土由岩石碎屑(崩积层、冰碛石和碎石)和冰(积雪压实、雪崩流和渗透水冻结)构成。这里永久冻土的形成取决于海拔高度(在法国所在的纬度这个高度通常高于2500米)、裸露程度与地貌环境(地表是否存在冰川,是否存在起隔热作用甚至作为冷阱的粗碎屑沉积物)、地形特征(遮阴作用、冷空气碗(cold air bowl)效应等)。

  地表形态中永久冻土的标准结构包括以下几个主要部分:

  • 一个厚达几米、导热性不良、永不冻结的表层,即活动层;
  • 一个由冰和岩石碎屑混合物构成的永冻层,可能是均质(“冰混凝土ice concrete)”饱和度为30%至40%)也包括局部的异质性(既有被冰透镜体“过饱和”的多年冻土,也有含有少量空气和融冰的“不饱和”多年冻土,融水流动的通道和积水处等)。
  • 一个很少冻结的基岩层或由未冻结的不饱和碎屑组成的第三层。

  冰混凝土层中冰的比例是地貌动态的决定因素。如果冰混凝土中的冰饱和或过饱和,永久冻土就可能沿着山坡缓慢移动,以石冰川的形式到达海拔较低的地区,这在法国阿尔卑斯山区非常多见,从马尔康杜(Mercantour)直到瓦努瓦兹(Vanoise)。

环境百科全书-永久冻土-石冰川
图3. 石冰川,劳理查德摄(上阿尔卑斯省,Hautes Alpes)石冰川陡峭的边缘(阴影),还有与石冰川流动相关的地表形状(沟槽和凸起)都很明显。[来源: Bodin X. (2007). Functioning, distribution and recent evolution of the permafrost of the Combeynot massif (Hautes Alpes, France). PhD thesis: University Denis-Diderot, Paris, 274p. https://tel.archives-ouvertes.fr/tel-00203233]

  石冰川rock glaciers)在山地景观中清晰可见,是永久冻土最明显的指示指标之一,其分布范围和对气候波动的响应差异都具有重要意义。石冰川主要分布在冰川不能充分发育且相对干燥的地区。构成石冰川的岩石碎屑和冰混合物在倾斜基底上蠕动,形成由隆起的脊和陡峭的锋相嵌套的特殊形态(图3)。

  石冰川存在与否,以及其形态和功能取决于岩石碎屑和冰之间数量的可变平衡。在区域尺度上,这取决于气候和地质环境;在局地尺度上,则由地形气候和地貌环境[3]所决定。

  根据所观察到的多样的环境条件,说明大多数石冰川起源于冰缘(即冰来自于将埋压在碎屑下的雪和深层冻结水),但并不排除冰川冰的存在(即最初是由地表的雪粒压实形成的)。最后应该指出的是,无论冰的来源如何,只有永冻层的温度才是石冰川发育和维持的关键因素。

环境百科全书-永久冻土-“化石”石冰川
图4. 位于康贝诺特(Combeynot)山体(上阿尔卑斯省)的瓦伦德拉路线(Vallon de la Route)上的“化石”石冰川(=目前整体上未见任何移动)

  石冰川沿斜坡流动,填满高处的山谷,搬运大量物质,随着第四纪气候的波动,石冰川的发育速度也不断变化。如同完全由冰构成的真实冰川一样,石冰川在中长期内也会受气候变化的影响并留下明显的痕迹。虽然冰川冰碛的规模很小,但是在冰川融水的作用下不断移动,因而虽然阿尔卑斯山的石冰川位置没有发生改变,但是冰舌已经推进到了海拔1500米处。需要指出的是,只有最高处的石冰川是最近才形成的,仍然含有冰且可能还在移动。一般认为石冰川“活动”的极限高度(阿尔卑斯山区是在2500到3000米之间)和不连续永久冻土分布下限大致相当。在海拔更低的地方可能分布着“零散”或“孤立”永久冻土,但是只分布在非常特定的地形和温度条件下,如受冷空气影响的多孔或喀斯特化岩石[4]:在阿尔卑斯山麓查特(Chartreuse)和韦科尔(Vercors)地区称为“冷岩屑(cold scree)”和“冰盒(ice boxes)”。

4. 与冻土合并有关的风险

  高山永久冻土几十年来一直在响应气候的变化,如冰川消融。在很多高山地区,永久冻土的温度已经上升到接近0℃。与此同时,活动层(即夏季融化的表层部分)变厚,地下冻结层的流变性显著改变。最终,高山多年冻土的分布下限会逐渐升高。

  高山永久冻土下部边缘的演变(法国所在纬度附近,大约位于海平面以上2300至3200米之间),与气候失衡,这一变化引发了地质灾害及其它相关风险。事实上,由于永久冻土内部冰的减少,内聚作用消失,永久冻土上部的稳定性降低,使得多年冻土退化,进而导致重力塌陷、冰缘失稳和融冰急流等现象激增。

  永久冻土暖化后会影响国土安全,主要有四个方面:

  • 由于冰川融化,碎屑堆积物沉降已经影响到瑞士和法国的一些滑雪场和高海拔地区的一些设施[5]
  • 在较陡的山坡冰冻碎屑堆积物失稳首先会使内部形变加速(在阿尔卑斯山有很多这样的案例),随后会引发冰冻体破裂,从而使得整个堆积物发生移动(乌巴耶的Le Bérard石冰川就是这样的[6]);
  • 高海拔地区的岩石墙体受重力过程影响的频率增加,墙体连接处的冰融化可能是布伦瓦和德鲁斯最近发生墙体崩塌的原因[7]
  • 熔岩流和泥石流的频率增加,这可能是由于永久冻土的活跃层厚度增加(如瑞士阿尔卑斯山区瓦莱州Ritigraben地区的泥石流[8]和法国萨瓦省兰斯列维拉德的Col du Lou石冰川),或是由于岩石沉积物输入增加,在发生大的降雨事件后出现移动(如发生在上萨瓦省阿曼塞特的泥石流)。

 


参考资料及说明

封面照片:2008年加拿大哈德逊湾泥炭沼泽上的永久冻土解冻池。[来源:Steve Jurvetson[CC BY 2.0],维基共享资源]

[1] Müller S.W. (1947) Permafrost and permanently frozen ground and related engineering problems. J.W. Edwards ed., 231 p.

[2] Bodin X., Lhotellier R., Schoeneich P., Gruber S., Deline P., Ravanel L. & Monnier S. (2008) Towards a first assessment of the permafrost distribution in the French Alps. Swiss Geoscience Meeting, 21-23 November 2008, Lugano

[3] 当地的地形和斜坡暴露条件

[4] 有裂缝和溶蚀洞,如石灰岩

[5] Fabre D., Cadet H., Lorier L. & Leroux O. (2014) Detection of permafrost and foundation related problems in high mountain ski resorts. IAEG Congress Torino, in Lollino et al, Springer, vol 1, paper 60, 321-324

[6] Schoeneich P., Bodin X., Echelard T., Kaufmann V., Kellerer-Pirklbauer A., Krysiecki J.-M. & Lieb G.K. (2014) Velocity changes of rock glaciers and induced hazards. in Lollino G., Manconi A., Clague J., Shan W., Chiarle M. (eds): Engineering Geology for Society and Territory – Volume 1, Springer, pp. 223-227. DOI: 10.1007/978-3-3-319-09300-0_42

[7] Ravanel L., Deline P. et al (2007) Ecroulement en haute montagne à permafrost : l’exemple du petit Dru (Massif du Mont-Blanc). Annual meeting of the Société Hydrotechnique de France (Nivologie-Glaciologie), Grenoble

[8] Rebetez M., Lugon R. et al (1997) Climatic changes and debris flows in high mountain regions: the case study of the Ritigraben Torrent (Swiss Alps) – Climatic Change 36, 371-389


环境百科全书由环境和能源百科全书协会出版 (www.a3e.fr),该协会与格勒诺布尔阿尔卑斯大学和格勒诺布尔INP有合同关系,并由法国科学院赞助。

引用这篇文章: SCHOENEICH Philippe, FABRE Denis (2024年3月13日), 永久冻土, 环境百科全书,咨询于 2024年10月31日 [在线ISSN 2555-0950]网址: https://www.encyclopedie-environnement.org/zh/sol-zh/permafrost/.

环境百科全书中的文章是根据知识共享BY-NC-SA许可条款提供的,该许可授权复制的条件是:引用来源,不作商业使用,共享相同的初始条件,并且在每次重复使用或分发时复制知识共享BY-NC-SA许可声明。

The permafrost

Encyclopédie environnement - permafrost - pergélisol

Permafrost is present on the Earth’s surface, particularly in the Northern Hemisphere. Its thickness and continuity depend on latitude and altitude. There are two main categories of permafrost: a thick, continuous permafrost that occupies the large areas of the continental shelves of Alaska, Canada and Siberia; and a thinner, often discontinuous or even sporadic permafrost, which concerns mountain ranges, particularly the alpine ranges. In these, rocky glaciers constitute a remarkable form, whose genesis and behaviour are the subject of special studies, different from those traditionally carried out on “real” glaciers. This article also discusses the risks associated with mountain permafrost in the context of climate change.

1. Definition and distribution of permafrost

The concept of permafrost (English name) or pergelisol (French name) was first defined in 1947 [1] and has since been an important part of cryospheric studies.

Permafrost is a thermal and temporal phenomenon that refers to subsurface terrain whose temperature never rises above 0°C for at least one year. It can affect all types of materials: bedrock, surface formations, soils. It may or may not contain ice: in rock, the amount of ice is generally limited to filling cracks, while in surface formations it may be important: fill the entire interstitial space (saturated permafrost), include small layers or lenses of ice, and exceed the proportion of rock material (supersaturated permafrost) by volume.

Permafrost represents about 20% of the Earth’s continental surface, or 25 million km2, a quarter of the land area of the Northern Hemisphere. By way of comparison, continental ice (excluding sea ice) covers 16 million km2.

Encyclopedie environnement - permafrost - pergelisol - carte hemisphère nord
Figure 1. The image shows the continuous permafrost area in red and the discontinuous and sporadic permafrost areas in orange. [© hkeita/shutterstock]
Depending on the proportion of the total area covered by permafrost, a distinction is usually made, depending on latitude (or altitude):

  • the continuous permafrost zone (more than 80% of the surface area),
  • the discontinous permafrost zone (between 30 and 80% of the surface area),
  • sporadic permafrost (less than 30% of the surface),
  • permafrost in isolated spots.

While most permafrost occurs at high latitudes, it is also found at high altitudes in mountainous areas. Thus in the Alps, a discontinuous permafrost is potentially present above about 2500 m in a northerly direction, a more continuous permafrost above 3500 to 4000 m. According to model calculations, permafrost could cover an area of 1300 km² in the French Alps [2], more than twice the surface area of glaciers (about 500 km²).

2. Structure of the permafrost

Encyclopédie environnement - permafrost - pergélisol - Profil thermique vertical typique du permafrost - thermal profil of permafrost
Figure 2. Typical vertical thermal profile of permafrost (with maximum and minimum temperature curves) and corresponding structures: active layer = temperature that can seasonally exceed 0°C; permafrost stricto sensu = temperature strictly lower than or equal to 0°C.

The formation, persistence or disappearance of permafrost depends very closely on the climate. Its distribution, temperature and thickness respond to changes in the natural environment and anthropogenic disturbances, resulting in a change in the ground’s thermal regime. The vertical structure of permafrost, in particular its ice content, is dependent on both climate and topographic, geological and geomorphological conditions (Figure 2).

On the typical thermal profile, three levels are clearly visible:

The surface layer, whose temperature exceeds 0°C in summer (and therefore thaws seasonally), is called the active layer. Strictly speaking, permafrost therefore only concerns the layer below the active layer, whose temperature remains permanently below 0°C. The active layer can be a few tens of centimetres thick in the peaty soils of the Arctic tundra, and up to 3 to 7 metres thick in ice-poor rocky terrain in the Alps.

The layer that never thaws is the permafrost in the strict sense. Below the level at which the maximum and minimum temperature curves meet (Tmin and Tmax) the terrain does not undergo annual oscillations in air temperature. This maximum penetration depth of annual variations is highly dependent on ice content. It can be as short as a few metres in ice-rich terrain, and as long as 20 to 30 metres in rocky terrain in the Alps.

The depth of the permafrost base is determined by the mean local air temperature, which conditions the permafrost air temperature, and by the geothermal gradient: the deepest permafrost thus corresponds to the coldest and driest climates (low snowfall shortens the insulating effect provided by snow). For example, the permafrost is several hundred metres deep in the far north of Canada or in Siberia. In the Alps, drilling carried out between 1998 and 2010 has shown that at an altitude of 3000 metres, permafrost can reach a thickness of more than 100 metres.

The interaction between the climate above the ground and the climate below its surface is complex and depends on multiple factors, many of which are sensitive to climate change. Thermal oscillations in the atmosphere are generally damped with depth due to the thermal conductivity of the subsoil and the snow cover. There is generally a time lag between changes in ground surface temperature and changes in depth in permafrost; in the case of a thick permafrost (North America, Siberia…), this lag can be in the order of hundreds to thousands of years, in that of a thin permafrost (Alps,…), it is counted in years or decades.

3. Permafrost and alpine rock glaciers

Any type of land is likely to be affected by permafrost, whether it is bedrock or sediment.

In the case of a rocky massif, we will be dealing with a rock that is more or less fractured and “cemented” by ice. The proportion of ice is limited to crack filling and may be almost nil in the case of a poorly fractured rock, but it can play a significant role in the stability of rock masses.

In the case of surface formations, permafrost is likely to be formed from rock debris (colluvium, moraine and scree) and ice (from snow compaction and avalanche flows and infiltration water freezing). The conditions under which this permafrost can form depend on the altitude (generally higher than 2500 metres in our temperate latitudes), the exposure and the geomorphological context (presence of glacier; presence of coarse detrital deposits acting as thermal insulation, or even as a cold trap, for the ground) and topography (shading effect, cold air bowl, etc.).

The standard structure of a permafrost in surface formations is composed of:

  • a permanently unfrozen surface layer that can reach a thickness of a few metres, which is not very thermally conductive and corresponds to the active layer,
  • a layer of permafrost, a mixture of ice and rock debris, sometimes homogeneous (“ice concrete” saturated with 30 to 40% ice), also including local heterogeneities (permafrost “supersaturated” with ice lenses, permafrost “undersaturated” containing a little air and melting ice; channels and pockets” of melting water…),
  • the bedrock itself (rarely frozen) or a third layer of unfrozen and unsaturated debris.

The proportion of ice in the ice concrete layer is a determining factor in geomorphological dynamics. If this concrete is saturated or supersaturated with ice, permafrost is likely to flow by creep on the slopes, which allows it to be found at lower altitudes, particularly in forms called rock glaciers, which are very numerous in the French Alps, from Mercantour to Vanoise.

Encyclopédie environnement - permafrost - pergélisol - glacier rocheux de Laurichard - rocky glacier laurichard france
Figure 3. The rocky glacier of Laurichard (Hautes Alpes). The steep edges are well marked (shadows), as well as the shapes related to the flow of the rocky glacier (grooves and bulges). [Source: Bodin X. (2007). Functioning, distribution and recent evolution of the permafrost of the Combeynot massif (Hautes Alpes, France). PhD thesis: University Denis-Diderot, Paris, 274p. https://tel.archives-ouvertes.fr/tel-00203233]
Rock glaciers are among the most relevant indicators of permafrost, as they are clearly visible in the mountain landscape, and are remarkable both for their extent and their variable response to climate fluctuations. They occur particularly in relatively dry areas where glaciers cannot fully develop. Rock glaciers acquire their very particular morphology (Figure 3), made up of nested bulges and a steep front, by creeping the mixture of rock debris and ice on a sloping substrate.

The presence or absence of rock glaciers, their morphology and functioning depend on the variable balance between the supply of rock debris and ice, which in turn are conditioned at the regional level by the climatic and geological context and, at a more local level, by the topo-climatic and geomorphological context [3].

The diversity of situations observed shows that most of the rock glaciers have a periglacial origin (i.e., the ice comes from burying snow under debris and freezing deep water), which does not exclude the presence of glacial ice (formed initially at the surface by the compaction of a neve). Finally, it should be noted that, regardless of the origin of the ice, only permafrost thermal conditions will allow the development and maintenance of a rocky glacier.

Encyclopédie environnement - permafrost - pergélisol - Le glacier rocheux « fossile » - rock glacier
Figure 4. The “fossil” rock glacier (= without any global movement currently detectable) of the Vallon de la Route, in the Combeynot massif (Hautes Alpes)

Rock glaciers, developed at varying rates depending on Quaternary climates, flow on the slopes and fill the high valleys, displacing considerable masses of material. Like glaciers, which are made up entirely of ice, rocky glaciers are subject to the vagaries of the climate in the medium and long term and leave obvious traces in the landscape. While glacial moraines are small in size, often dismantled by glacial meltwater, rocky glaciers remain in place and now spread their tongues up to 1500 metres above sea level in the Alps. However, only the highest of them, and therefore the most recent, still contain ice and may be in motion. It is generally accepted that the “activity” limit altitude of these rock glaciers (between 2500 and 3000 metres in the Alps) roughly corresponds to the lower limit of the discontinuous permafrost. A possible permafrost found at a lower altitude will be described as “sporadic” or in “isolated spots”. It can only correspond to very specific morphological and thermal situations, for example those linked to cold drafts in porous or karstified systems [4] : “cold scree”, “ice boxes” identified for example in the pre-Alpine mountains of the Chartreuse and Vercors.

4. Risks related to the merger of permafrost

Just as glaciers are retreating, alpine permafrost is responding to climate change that has been underway for several decades. First, its temperature rises to and approaches 0°C in many alpine sites. At the same time, the active layer, this surface portion that thaws in summer, thickens and the rheology of the frozen levels in the ground changes significantly. In the end, the lower limits of the alpine permafrost are expected to gradually increase in altitude.

It is the evolution of this margin (roughly located between 2300 and 3200 metres above sea level in our latitudes), which is out of balance with the climate, that raises major questions in terms of hazards and associated risks. Indeed, the degradation of permafrost could play a significant role in the upsurge of gravity, periglacial and torrential phenomena, due to the loss of the cohesive role of ice in stabilizing the upper slopes.

The consequences of permafrost warming that could affect our territories are of four kinds:

  • the subsidence of detrital deposits, linked to ice melt, has already affected some ski resorts and high altitude installations in Switzerland and France [5];
  • the destabilisation of frozen detrital deposits located on marked slopes would initially result in a significant acceleration of internal deformations (many known cases in the Alps), then in a rupture likely to mobilise the entire deposit (probable case of the rock glacier of Le Bérard in Ubaye [6]);
  • the increase in the frequency of different gravity processes affecting high-altitude rock walls; the melting of the ice contained in the wall joints is probably the cause of the recent collapses at the Brenva Spur and Drus [7];
  • the increase in the frequency of torrential lava and mud flows, either by deepening the active layer of permafrost (case of Ritigraben, Valais, Swiss Alps [8], and the rock glacier of the Col du Lou in Lanslevillard, Savoie) or by increasing sedimentary inputs from the walls, which can therefore be mobilized during major rain events (case of the Armancette torrent, Haute-Savoie).

 


References and notes

Cover photo: Permafrost thaw ponds on peat bogs in Hudson Bay, Canada in 2008. [Source: Steve Jurvetson[CC BY 2.0], via Wikimedia Commons ]

[1] Müller S.W. (1947) Permafrost and permanently frozen ground and related engineering problems. J.W. Edwards ed., 231 p.

[2] Bodin X., Lhotellier R., Schoeneich P., Gruber S., Deline P., Ravanel L. & Monnier S. (2008) Towards a first assessment of the permafrost distribution in the French Alps. Swiss Geoscience Meeting, 21-23 November 2008, Lugano

[3] Local terrain and slope exposure conditions

[4] with open cracks and dissolution cavities, as can be found in limestone rocks

[5] Fabre D., Cadet H., Lorier L. & Leroux O. (2014) Detection of permafrost and foundation related problems in high mountain ski resorts. IAEG Congress Torino, in Lollino et al, Springer, vol 1, paper 60, 321-324

[6] Schoeneich P., Bodin X., Echelard T., Kaufmann V., Kellerer-Pirklbauer A., Krysiecki J.-M. & Lieb G.K. (2014) Velocity changes of rock glaciers and induced hazards. in Lollino G., Manconi A., Clague J., Shan W., Chiarle M. (eds): Engineering Geology for Society and Territory – Volume 1, Springer, pp. 223-227. DOI: 10.1007/978-3-3-319-09300-0_42

[7] Ravanel L., Deline P. et al (2007) Ecroulement en haute montagne à permafrost : l’exemple du petit Dru (Massif du Mont-Blanc). Annual meeting of the Société Hydrotechnique de France (Nivologie-Glaciologie), Grenoble

[8] Rebetez M., Lugon R. et al (1997) Climatic changes and debris flows in high mountain regions: the case study of the Ritigraben Torrent (Swiss Alps) – Climatic Change 36, 371-389


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引用这篇文章: SCHOENEICH Philippe, FABRE Denis (2019年2月7日), The permafrost, 环境百科全书,咨询于 2024年10月31日 [在线ISSN 2555-0950]网址: https://www.encyclopedie-environnement.org/en/soil/permafrost/.

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