Glacial Hazards References Revision

Srestha et al., 2023

• As glaciers recede and surrounding slopes become increasingly unstable, GLOF events are expected to increase; between 1833 and 2022 there were 697 individual GLOFs documented in High Mountain Asia with nearly 7000 fatalities

• High Mountain Asia has the largest expanse of glacial ice between the two poles and has around 30,000 glacial lakes but these have been retreating and losing mass since the 1960s leading to the formation and rapid expansion of glacial lakes, a trend expected to create new hotspots of hazardous lakes with implications for GLOF hazards and risk

• Processes identified as direct or indirect triggers include slope movements such as rockfalls, avalanches or landslides into lakes to form overtipping waves as well as intense rainfall or ice melt leading to an increase in water levels that strain dams; these then cause fatalities as well as damaging infrastructure and farmlands as developments grown in downstream areas to increase risk

• There is a peak in GLOFs seasonally where westerlies bring South Asian monsoons to show that regional precipitation is an important driver of outburst flooding in the region

• The hazard of a GLOF is closely associated with moraine stability which is linked to the history of glacier retreat with areas of recent permafrost change likely to be more susceptible to mass movement

• Distributed datasets on infrastructure, population and ecosystems would allow for assessments on impacts and vulnerabilities when coupled with potential paths and remotely sensed vegetation data; this would allow for estimates of local economic and ecological impacts to form hazard zonation maps

Miner et al., 2020

• In the Mount Everest Region risks arise from a natural and anthropogenic changes to the biological system leading to diverse risks to ecosystems, human health, geology and climbing conditions; as high mountain glaciers worldwide decrease in extent and volume there are significant consequences to water availability, hazards such as outburst floods and slope failure, ecosystems and socioeconomic futures

• There are risks of seismic hazards, landslides and avalanches as well as rockslides that become more frequent as glaciers melt away from headwalls and expose steep unstable rock faces

• Rain events can trigger flooding, often this water can be contaminated by chemicals, pesticides and anthropogenic metals meaning that drinking water sourced from snow and ice melt poses a risk to human health; climbers can also lead pathogenic organisms in meltwater

• These risks are diverse and constantly changing so much be monitored in order to inform proper adaptation and mitigation of risks to tourism and local populations

Worni et al., 2014

• Many recent GLOF events involve process chains where mass movement impacts glacial lakes to trigger dambreaches and cause outburst floods; the effects of climate change and increased instability of high mountain slopes pose a threat as they may exacerbate process chains 

• GLOF events compromise a series of cascading processes that should be modelled to improve our understanding and assessment of future hazards as new glacial lakes form and slopes destabilise

• The initiation of process chains can differ e.g. rock fall, precipitation, upstream GLOF but they typically begin with an impulse-wave generation, dam overtopping and breaching and then lake emptying and flood propagation

• The stability of dams depends on their geometry, internal structure, material properties and particle size/distribution; once they are overtopped they initiate dam erosion that continually increases hydraulic forces to enlarge the breach in an irreversible process leading to the emptying of the lake

Sherpa et al., 2019

• GLOFs are among the most serious cryospheric hazards for mountain communities and people’s perceptions of cryospheric risks can influence their actions, beliefs and responses to hazards; there has been a positive correlation found between perceptions of risk and livelihood sources of tourism and spatial proximity to glacial lakes

• There is much uncertainty and confusion related to GLOF risks often stemming from a disconnect in how scientific information is communicated to local communities, how policies are formed and awareness campaigns; there is a need to form a sustainable partnership of scientists, policymakers and local communities to improve cryospheric risk management 

• Only in recent years have social and humanistic perspectives on GLOFs emerged, but there is a need for an interdisciplinary approach to capturing the natural-social interactions of cryospheric hazards and appreciating that people's risk perceptions are shaped by direct personal experiences and second hand information, this perception influence how a person may act in the event of a hazard

• Rapid onset hazards have a perceived higher risk; local perception was also influenced by source of livelihood, age, prior experience and geography with younger people more likely to perceive a risk alongside those who support their livelihoods with tourism, those with prior experience of the hazard and living closer to lakes

Bajracharya et al., 2007

• Information on the extent and possible impact of GLOFs can be used for designing early warning systems and implementing management plans for lakes such as Imja Lake which is the largest and most dangerous in the Sagarmatha region

• Flooding occurs due to the breaking down of moraine dams leading to flash floods and debris flow downstream, pressures are increasing due to increased populations and tourism in mountain areas causing people to settle in areas highly exposed to natural hazards and trekking routes often leading through unsafe areas in floodways

• The most vulnerable areas were identified as settlements with agricultural land along river banks with scattered housing in vulnerable zones; around 5.8km of trails were judged as highly vulnerable due to running through flood plains

• Vulnerability maps generated through hydrodynamic modelling provide a systematic basis for identifying vulnerable populations, infrastructure and agricultural land and this can be used to develop management plans

Emmer, 2017

• Glacier retreat is connected to interrelated geomorphological processes and changes in hydrological regimes

• GLOFs are characterised by extreme peak discharges, exceptional erosion and transport potential and pose risks to human society potentially driven by anthropogenic climate change

• Despite regional differences in triggers and mechanisms, GLOFs are closely tied to the formation and evolution of new lakes and triggers

Salerno et al., 2017

• From the 1950s to 1990s there has been an overall decrease in glacier area as a result of temperature and precipitation variation, this is important as ice masses in the Himalayas constitute a water resource assuring the survival of around 500 million people in the area 

• The glaciers of the Sagarmatha national park are nearly all debris-covered, a characteristic that alters exchanges between ice and the atmosphere with the debris cover gradually increasing towards the lower part of the glacier ablation zone

Cenderelli & Wohl, 2001

• GLOFS can dramatically modify channels and valleys in the regions they affect by eroding, transporting and depositing large quantities of sediment for tends of km along flood routes

• GLOF discharges in the Mount Everest region were 7-60x greater than seasonal high flow flood discharges, with the greatest discharge occurring nearest to the moraines and declining downstream

Benn et al., 2012

• Superglacial debris cover can alter rates and spatial patterns of melting, this can be associated with the formation of moraine-dammed lakes that pose a risk of GLOFs as downwasting allows for supraglacial lake hollows to extend

• The probability of a flood is a function of lake volume, the geometry and structure of the dam and possible trigger mechanisms; these events can then lead to a loss of life, dwellings, infrastructure and farmland

• A major factor in determining GLOF potential is the hydraulic gradient across the moraine dam influencing its susceptibility to seepage as well as trigger mechanisms that can cause waves to overtop and erode moraine dams to initiate positive feedback loops of discharge and erosion

• At risk sites there is a need to continue to monitor the complex webs of factors that contribute to the occurrence of GLOF hazards through in situ and remote sensing techniques, predictions of GLOF impact should be based on a scientific basis and have clear criteria for prioritising mitigation efforts

Hambrey et al., 2008

• Many Himalayan glaciers are enclosed by Little Ice Age moraine complexes which impound lakes, these dams can attain heights of over 100 metres and are made up of poorly sorted mixtures of sand and gravel; behind the dams there are lakes several kilometers long 

• During a GLOF, discharges of up to 60x greater than normal flow have been reported with a particularly high impact in the upper 16km of flood routes and with further consequences up to 200km downstream

• At debris covered glaciers downwasting (or vertical thinning) combined with a progressive reduction in slope profile sees supraglacial debris thicken towards the snout, forming and adding to terminal moraine dams behind which lakes are fed by glacial melt and precipitation, and expand due to cliff calving

Zheng et al., 2024

• A GLOF occurred in June 2020 in Tibet with a peak discharge of 5602 cubic meters per second, the landslide triggering the GLOF was likely caused by heavy south Asian monsoon rainfall in the same month that led to dam overtopping and erosion

• There were no casualties but there was severe destruction to villages and infrastructure downstream mainly to buildings, roads, bridges and farmland; there was great erosion of the river valley and alteration of the channel

• As the event took place in the daytime, villagers were upstream collecting herbs and were able to observe the flood and inform downstream populations to evacuate, leading to no casualties in this event

Cuffey & Paterson, 2010

• A jokulhlaup is the sudden and rapid drainage of a glacier-dammed lake that can cause extensive flooding and pose a great hazard to populations downstream

• They can occur once per year or only every several years, the flood can start when the level gets very high and may stop before the lake has emptied

• These floods often occur due to melt and transport sediment that is deposited in broad outwash plains at the periphery of ice caps

Motschmann et al., 2020

• GLOFs and water scarcity are often assessed by separate methods and by separate research communities despite being intertwined and shaped by multi-dimensional natural and socioeconomic drivers

• GLOF threat increases at the same time as declining melt water supply changes in the hydrological regime resulting in changing water availability

• There is a need to form more comprehensive analysis of risks related to water resources by considering climate change within multi-dimensional drivers across different scales and complex climate sensitive mountain regions to include local perspectives on risk reduction, adaptation and water management

Washakh et al., 2019

• In Nepal, there is a further risk posed to river basins housing hydropower plants that are key to generating income, forming reliable power sources and alleviating poverty

• If these power plants are hit by high discharges, they may be damaged or destroyed, leading to socioeconomic decline throughout the region

• In light of these wide ranging risks associated with GLOF events, there is a clear need to provide comprehensive risk assessments of fragile water and energy systems

Kumupulainen, 2006

• Vulnerability refers to the susceptibility of people, communities or regions to natural or technological hazards through three key dimensions of economic, social and ecological vulnerability

• Risk = hazard potential x exposure x vulnerability; vulnerability can be measured in terms of economic damage potential (economies, communication networks, infrastructure, production, distribution, consumption etc.), social coping capacities (the poorest find it harder to reconstruct their lives after a hazard) or ecological (ecosystems response to shocks)

• Vulnerability is broadly defined as the potential for loss but can be understood, measured and mapped in different ways; in the future there is a need to continue to research hazard centred and region centred vulnerability

United Nations Office for Disaster Risk Reduction, 2017

• Hazard is defined as a dangerous phenomenon, substance, human activity or condition that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption or environmental damage

• Risk = hazard potential x exposure x vulnerability; this combines the probability of an event and its negative consequences to calculate the potential loss of life, injury or destroyed or damaged assets which could occur to a system, society or community in a specific period

Ding et al., 2021

• The cryosphere is very sensitive to global warming, with elevated temperature rise in high latitude and latitude areas it is dramatically changing through ice sheets melting, glaciers retreating, permafrost degrading and snow cover extent decreasing

• The atmospheric cryosphere involves hazards of frost, hail, freeze rain and extreme winter events; the oceanic sea ice, icebergs, coastal erosion and sea level rise; the land glacial hazards, collapse, debris flow as well as heavy snowfall, avalanches, flooding and permafrost hazards that all have effects to human livelihoods, economic assemblages, ecosystems and infrastructure in varied manners

• Although the cryosphere is shrinking as a result of climate change, cryospheric hazards will likely increase in both frequency and severity in a warming climate

Elia et al., 2023

• There has been less attention paid to natural hazards occurring in cryospheric environments than those in mid-latitudes as a result of periglacial regions hosting smaller human populations and therefore understanding and modelling hazards is seen as less prominent of a concern; however, this is changing as global warming radically changes periglacial surface processes and geomorphological processes

• Degrading permafrost has led to regressive thaw slumps and active layer detachments as types of cryospheric slope failure hazards, their development negatively affects human settlements, infrastructure and ecosystems due to changes to sediment budgets and releases of methane and carbon dioxide as permafrost melts 

• As a result, data-driven models were formed in order to improve understanding of cryospheric dynamics, map the susceptibility to certain slope failures and quantify potential impacts 

• The modelling protocol was successfully able to map areas prone to land failure and summarise this into a multi-hazard susceptibility map for Northern Alaska that could be used to mitigate against damage to infrastructure and ecosystems, as well as highlighting the role of unconsolidated materials, temperatures and snow covers in the incidence of these hazards

• Models are limited in their transferability meaning there should be more efforts to map cryospheric multi-hazards in ways that can be helpful in tailoring local adaptation and mitigation strategies

Nicu et al., 2023

• The Svalbard Archipelago represents the northernmost place on Earth where cryospheric hazards including thaw slumps and thermo-erosion gullies could take place and develop due to climatic variations, as permafrost is very sensitive to warming there is a need for a deeper understanding of processes to foresee the dynamics of hazards and future global implications

• Permafrost thawing of internal ice within soils often leads to subsidence and slumps called thermokarst which threats ecosystems, infrastructures and cultural heritage sites alongside releasing GHGs into the atmosphere; in Svalbard thaw slumps and thermo-erosion gullies are of particular interest in the multi-hazard model to understand how they may occur in the same terrain and be mutually triggering 

• Multi-hazard assessment is part of Agenda 21 for Sustainable Development and is highlighted due to the combination of one or more hazards together being more threatening than one, this is especially applicable to cryospheric hazards where little knowledge exists on hazard dynamics

• Data driven models were used to form a multi-hazard susceptibility model of Northern Svalbard to these processes and revealed that different factors drove each, as well as identifying high-risk zones as an important tool for urban planning and risk management 

• This model was the first of its kind in high-Arctic environments and provides an important baseline for further studies of the changing landscape and developing quantifications of future risks to Arctic communities and ecosystems

Clague, 2013

• Glaciers are greatly impacted by climate change with their hazards amplified as a result, most Alpine glaciers reached their largest size near the end of the Little Ice Age but have all thinned and receded in response to warming in the Holocene

• Warming leads to glacier melt and sea level rise with the most catastrophic events predicted with changes to the Greenland and Antarctic Ice Sheets leading to widespread displacement of those living on shorelines and threats to coastal infrastructure

• The thinning and retreat of alpine glaciers have led to rock-slope failures due to declining stability of slopes, this debuttressing can be caused by glacier melt, freeze-thaw weathering and permafrost degradation; rock falls can pose hazards to climbers and tourists at increasing rates in the European Alps and similar areas

• Permafrost thaw and snow cover decline may also lead to an increased frequency of debris flows as a result of slope instability, ice avalanches may also occur as a result of changes to subglacial hydrology; streams may also be impacted due to changes in the delivery of water and sediments from glaciers

• There are theories that large scale deglaciation may be responsible for triggering seismicity or volcanism due to changing stresses on the lithosphere that may induce the upward movement of magma and trigger slipping

Smellie & Edwards, 2016

• Many of the most significant volcanic disasters in history are directly linked with volcano-water interactions including Krakatoa 1883 and Nevado del Ruiz 1895

• Ice-drapped and fully subglacial volcanoes may erupt or flood at any time of year, whereas non-ice clad volcanoes depend more strongly on annual climate variations and seasonal cycles; these eruptions can cause a range of local, regional or global hazards depending on the factors of magma and eruptive environments 

• Lava flows can melt snow and ice to cause floods, interact explosively with meltwater and form lava termini that are high;y fractured and susceptible to gravity driven failure; this was seen in Eyjafallajokull 2010 to transform subglacial tunnels into open channelised lava flows; lava domes can also interact with glaciers snow and ice such as Mt St Helens 1980

• Ash production tends to be more fine and at greater volumes and temporal scales for glaciovolcanic eruptions to cause risks for aviation, deposition onto snow and ice causing melting, contaminating drinking water and blocking water sources

• Pyroclastic density currents can interact with meltwater to cause rapid melting produce lahars, this can be a direct driver of mass flows where water combined with volcanic debris travel fast down steep volcanic slopes to devastate local populations and infrastructures; these can also be indirectly triggered by longer-term volcanic heat release into snow/ice craters

• Avalanches and lightning can also be associated with glaciovolcanism; eruptions can also influence the climate with short-term cooling and long-term warming expected to be greater from glaciovolcanism due to eruption rates increasing and more greenhouse gases being released into the atmosphere

Oppenheimer, 2011

• Volcanoes can release ash, gases and aerosols that block sunlight and form short-term global cooling; this can be mitigated or negated by the release of GHGs during the eruption leading to long-term warming

• Sulphur emission is critical to producing strong climatic forcing, sulphur rich magmas have low sulphur solubility so very explosive eruptions tend to be silicic rather than basaltic; magmas must also be highly oxidising or highly reducing to have the highest sulphur emissions

• Eruptions must be explosive and intense enough to penetrate the stratosphere in order to stay aloft and have a significant effect on radiation

Naranjo et al., 1986

• The small Plinian eruption of Nevado del Ruiz ejected huge amounts of mixed tephra into the atmosphere, it caused small pyroclastic flows and surges of the glacier to melt 10% of the volcanoes ice cap leading to meltwater floods; these floods incorporated soils and loose sediments from the flanks into lahars that claimed at least 25,000 lives

• The dispersal of tephra was extensive with ash falls reported more than 400km NE of the volcano, pumice scorched vegetation

• Minor pyroclastic flows destroyed buildings and melted the glacier to form major lahars once mixed with eroded soils and deposits 

• On the east flank, two lahars combined to inundate the town of Armero at about 11pm, most of the population was killed in two to three waves of this lahar; on the western flank around 1000 people were killed in Chinchina

• The principle source of water for lahars was the glacier on the Ruiz volcano, it is likely the glacier surged and broke up during the eruption or released much subglacial meltwater being stored in tunnels and crevasses near the crater to release huge amounts of water for the formation of high fluidity lahars

Edwards et al., 2020

• The use of a spatial database on global glacierized volcanoes can be used to identity where land ice and volcanoes co-exist on Earth, this is useful for future studies aimed at hazard reduction, projections of dangerous volcanoes, paleoclimate reconstructions and continued monitoring

• There are 245 Holocene volcanoes with glacier ice within a radius meaning it is likely to impact or be impacted by volcanism, this can be either partially or fully covered by glaciers and they are mostly found in subduction zones

• Volcanism can be affected by glaciation from source to surface due to changes in overburden pressure, dyke formation, stress regime variability and further impacts to explosivity and characteristics of lava; conversely volcanic eruptions can impact the mass balance of glaciers, create topographies for accumulation, ash cover can expedite wasting, decrease albedo and be affected by magma, lahars and dome emplacement 

• Globally nearly 7 million people live within 30km of a glacierised volcano and almost 160 million people within 100km, meaning they could be impacted by lahars or disruption to water sources

• The most dangerous volcanoes on Earth can be identified through this database through comparisons of eruption history, ice volume and nearby populations

Huggel et al., 2017

• Colombia hosts important glacier-clad volcanoes and public and scientific attention has been focused on these since the 1985 Ruiz/Armero disaster but ice mass extent, volume and structure now changes as a result of atmospheric warming to see glaciers recede at the same time as populations grow in a number of communities around the volcano

• Despite this recession of glaciers, significant volumes of ice are still present and are likely to impose a hazard for potential volcano-ice interactions

• There remains considerable hazard potential from Nevados del Tolima and Huila; notably Nevado del Ruiz is assessed as retaining the conditions conducive to a repetition of events comparable to the 1985 lahars

• Integrated monitoring using seismic stations and remote sensing should be used to assess these changes as well as mitigation attempts including early warning systems and education campaigns

Barr et al., 2018

• Volcanic activity has notable impacts on glacier behaviour, it is important to document and quantify these in an attempt to predict future glacio-volanic behaviours and improve monitoring and mitigation of hazards including floods and lahars 

• The frequency and nature of volcano-glacier interactions are likely to change with time, meaning predictions of future importance is difficult but is being improved through advanced remotely sensed data and observations

• Direct impacts of volcanoes on glaciers include subglacial heating, subglacial dome growth, subglacial eruptions, lava flows, PCDs, supraglacial tephra deposition, floods and lahars etc. to impact the future stability of glaciers that can have wider impacts on ice sheet collapse and global sea level rise; indirect impacts occur through the impact of volcanoes on the climate (e.g. short-term cooling and long-term warming) to influence glacier response to the changing climate 

• Volcanic activity directly affects glacier behaviour due to glaciers being located on active volcanoes or due to interactions with glaciers in adjacent regions

Benn & Evans, 2010

• Erosion in glacial environments results in familiar and characteristic forms and landforms, there are key variables that influence the process and pattern of erosion

• Glaciological variables influence processes and patterns of erosion including basal shear and stress, subglacial water pressure, drainage systems, flow direction, basal velocity and thermal regime as sliding and erosion can only happen when the basal ice is at the pressure melting point

• The substrate’s characteristics also impact erosion through the structure, lithology, jointing and weathering of the bed as well as the thickness and composition of unconsolidated sediments 

• Topographic variables encompass the morphology of the bed from small roughness areas to the relief of the whole catchment 

• Temporal and climatic variables can also influence erosion rates

Koppes et al., 2015

• Glacial erosion is key to understanding the role of Cenozoic-era climate change in the development of topography worldwide, but factors controlling rates of erosion of ice remain poorly understood; this seeks to be improved through examining sediment yields from 15 outlet glaciers from Patagonia to the Antarctic Peninsula

• Glacial erosion rates are expected to increase with decreasing latitude due to climatic control on basal temperature and the production of meltwater promoting sliding, erosion and sediment transfer; although ice fluxes, sliding speeds and erosion rates can be related to erosion it is revealed that climate and glacier thermal regime control erosion rates more than ice cover, flux or velocity 

• Most models have assumed that erosion rates are proportional to sliding velocity with the erosion rule linking sliding speed and bedrock erosion susceptibility as key controls; however, this does not take into account thermal regime although erosion rates for polar glaciers are considerably lower than temperate ones due to meltwater access at the bed

• Climate variation, more than ice dynamics, controls the temporal and spatial variability in erosion rates with a mean annual temperature of above 0-5 degrees being the threshold for fast erosion due to to ample supplies of meltwater at the bed

Cook et al., 2020

• There is much uncertainty on how glacial erosions should be parameterised in landscape evolution models, theories relating erosion rates to sliding and climate impacts lack empirical evidence and scrutiny 

• From 38 global glaciers sliding can be positively correlated with erosion rates, with the most rapid erosion achieved at temperate glaciers with high annual mean precipitation due to promoting the most rapid sliding

• This dataset shows that the conditions for erosion are optimised in the upper ablation area just below the ELA where the ice is thick and surface melt forms subglacial channels flushing sediment out at high water pressures; it concludes that latitude alone is an insufficient proxy for climate but draws attention to precipitation for the first time in increasing erosion due to enhancing sliding and sediment flushing 

• The exponent in the erosion rule is also equated to be less than 1, around 0.65 to be applicable for use and climate and sliding as key controls; however, there is a need for empirical studies of glacial erosion to expand

Fedotova & Magnani, 2024

• Recovering patterns of glacial erosion over time is key to understanding feedbacks between climate and tectonic processes, yet is often complicated by the incompleteness of the sedimentary record limiting the validity of findings 

• In the proglacial lake of Argentino Glacier there is a nearly completely preserved sedimentary record for the last 20,000 years, revealing a trend of glacial erosion rates increasing since the Cenozoic; yet this is not a systematic increase but rather occurs in intense erosional events separated by times of quiescence 

• This intermittent pattern of erosion is attributed to glacial responses to cooling and increased climate variability since the Cenozoic period

Benn & Evans, 2010

• Abrasion is the wear of rock surface by striation and polishing as rock particles are dragged over bedrock to score thin grooves and clasts, polishing smooths these as part of one processes; wear laws predict abrasion rate to be based on the concentration of particles in basal ice, particle velocity, normal stress at the bed and rock hardness with a higher stress and velocity leading to greater abrasion rates

• Rock porosity can also be used as a proxy for rock strength as high-porosity rocks such as sandstone experience higher wear that low-porosity granite and metamorphic rocks

• Quarrying sees large fragments of rock detach from the parent mass through enlarging cracks and joints and abrasion processes, this relates to water pressures at the bed and within cracks

• Under cold beds sliding is negligible meaning abrasion is not effective, but plucking may take place where the ice freezes onto rock in bedrock fractures and removes entire blocks, this is effective in heavily fractured bedrock

• At soft beds unlithified materials can be mobilised by glacial stresses and the failure of sediment at the yield strength, fragments of sediment and weak rock can detach but disaggregation is controlled by frictional strength

Schneider et al., 2011

• Large rock-ice avalanches cause high numbers of fatalities, and this is being increased due to the impact of climate change on rock slope stabilities in high mountain areas with possible hazardous consequences in densely populated high mountain regions; therefore, improving hazard assessment mobility is critical 

• The changing climate leads to thinning and area decline of glaciers, which leads to stress redistribution (debuttressing) and slope instabilities; this can also degrade permafrost and allow meltwater to penetrate joints and lead to thermal perturbations of fractures leading to mass movements 

• Laboratory experiments show that the volume of granular ice increases mobility of the flow, but water is a larger and key driving factor in improving mobility and increasing the travel distance of the avalanche

• The frictional surface of the flow paths and topography such as channeling are also key, this can be used to help find ranges for friction parameters in scenario modelling and hazard assessments

Evans et al., 2009

• In September 2002 a catastrophic geomorphic event occurred in the Caucasus Mountains in southern Russia where almost the entire mass of Kolka Glacier detached from its bed and accelerated to a high velocity of up to 80m/s over 19km as a glacier-debris flow

• This was seen as a response to ice and debris loading over a period of months prior to the detachment; the glacier detached from its bed due to a loss in effective stress due to excess water pressures at the glacier bed 

• Similar total detachment events can be termed ‘Kolka-type behaviours’

Leinss et al., 2021

• In the Petra Pervogo range in Tajikistan, satellite imagery has identified 17 mass flows involving glacier ice between 1973 and 2019; the large number of locally clustered events shows that the range has particularly favourable conditions for glacier instabilities due to easily erodible soft lithologies paid with rising temperatures

• In the case of a glacier mass slide, potential energy is transformed into kinematic and frictional heat which increases the content of liquid water to enhance the mobility and runout distance of rock-ice avalanches compared to rock-only avalanches; water is a key factor in reducing basal friction as well as stress changes and weak-bedrock; the melting of ice in ice-sediment mixtures can also lead to detachment 

• Detachments tend to occur in the summer and in years with high mean annual air temperatures above local trends, showing that high temperatures favour glacier detachments and rock-ice avalanches

Wolken et al., 2021

• Recent degradation of glaciers and permafrost in the Arctic has led to biogeochemical threats to ecosystems and human health, as well as impacts to infrastructures through reduced bearing capacity and an increase in the likelihood of landslides and rock avalanches

• This has led to an oil tank collapse in Norilsk, Russia 2020 releasing 21,000 cubic meters of diesel oil; there have also be complete water system failures in Point Lay and Wainwright, Alaska to many homes and buildings including a health clinic; since 2009 their drinking water sources are also being drained

• Permafrost temperatures are increasing due to long term gradual warming and extreme events such as warm summers, deep insulating snow cover and extreme precipitation 

• Mountain permafrost is often the least monitored meaning there is a need to better understand glacier permafrost hazards to better inform stakeholder decision making

Anacona et al., 2015

• In the extratropical Chilean and Argentinian Andes nearly 200 human deaths were linked to glacier and permafrost hazards during the C20th; this is often due to increasing frequency in GLOFs, rock-ice avalanches and lahars 

• Processes linked to the recession and thinning of glaciers and permafrost include the destabilisation of Alpine slopes due to stress redistribution, generation of outburst floods and debris flows and mass movement; the extratropical Andes are prone to these hazards and their vulnerability is exacerbated by the increased use of glacial and peri-glacial belts for mining, hydropower and tourism facilities

• The increasing frequency of GLOFs are linked to glacial retreat and the subsequent formation of glacial lakes, they can be triggered by landslides and rises in water levels but the cause of many outburst floods remains uncertain

• Mass movements and avalanches are related to extreme meteorological events and chain reactions; glacio-volcanic interacts are also seen to increase

• There is a lack of basic information on these events in the Andes; signalling a need to better document historical processes, examine temporal and spatial distribution and consider triggering factors to fill gaps in knowledge and improve modelling and mitigation efforts in the area

Edwards et al., 2015

• Volcanic eruptions beneath continental ice sheets are known as glaciovolcanism which encompasses volcanic interactions with ice as well as meltwater created by volcanic heating of ice

• Research has expanded in recent years since the massive flooding and enhanced tephra production of Eyjafjallajokill in 2010, the role of glaciers in landscape evolution, research in geology on Mars and paleoclimate proxies for ice sheets in time and space 

• The classic model assumes four stages describing changes in the nature of volcanic deposits and the enclosing of the ice sheet after the eruption; since this primary model, observations have increased around the nature and processes of glaciovolcanism

• Eruptions can be classed in three ways; the first is where eruptions occur under or within glaciers with the eruption style and behaviour dominated by the presence of water and ice; the second is where the ice exerts a profound influence on the eruption products often at snow and ice covered volcanoes leading to major flooding; the third involves only minor volcano-ice interactions

• With increased interest on glaciovolcanism there should be more research into constraints on melting rates, heat transfer mechanisms, morphologies of ice, links to climate change, glacial hydrology and ice mechanisms; advances in remote sensing will also improve real time monitoring of glaciovolcanic eruptions

Gudmundsson et al., 2012

• The 2010 Eyjafjallajokul eruption formed a modest ash cloud that was widely dispersed

• The ash cloud was around 80% airborne tephra which was mostly over 70 teragrams of fine ash

• About 50% of the tephra fell in Iceland with the remainder carried south and east detected over around 7 million square kilometer of Europe and the North Atlantic

• This was a level of dispersal that had not been anticipated for smaller explosive eruptions and lasted over weeks leading to unprecedented disruption to air traffic and vulnerability of modern society

Harris et al., 2012

• The ash cloud led to economic decline, response and airline issues; tourists reported being stranded and the ash cloud causing ‘chaos’ blaming government agencies for an inadequate response 

• The ash cloud drifted into transatlantic and European air routes and proved detrimental to aircraft operations leading to widespread closure of air space and airports; the impact was understood by millions beyond the scientific community

McEwen & Malin, 1989

• The eruption of Mount St Helens in May 1980 was a key volcanic event forming pyroclastic flows, rock-slide avalanches, lahars and the blast 

• The most voluminous pyroclastic flows occurred on May 18th covering an area of 15.5 square kilometers mostly North of the volcano

• Lahars began within minutes of the eruption and flowed down nearly all of the major drainage routes near the cone; a key formation of these was through the melting of debris laden ice and snow by hot tephra

• Lahar deposits ranged in texture from fine mud to coarse debris-flow deposits with the most voluminous and damaging flows occurring in the North Fork Toutle River