Last month in northern India’s remote Nubra Valley, a video captured stunning moving debris flow from a potential glacial event, like a GLOF. At a high altitude of 10,000 feet (or 3,048 meters above sea level), Nubra Valley is tucked in the northeast part of the Ladakh district, surrounded by Pakistan, Tibet, Xinjiang Province of China, and India’s Himachal Pradesh. As one of two valleys in Ladakh, Lonely Planet described Nabra as “a tuft of land of the very scalp of India” and home to the heavily glaciated peaks of the Karakoram Range, including the contested Siachen Glacier and two major rivers.
Heavy rainfall is a typical trigger for landslides, but as weather conditions were fair at the time, it seems more likely the region’s sensitive glacier systems may be the cause. Recently, the relationship between melting glaciers, particularly permafrost and landslides has been studied in Alaska, and one recent study concluded climate change is expected to cause larger and more frequent avalanches due to the melting permafrost.
For more information on how climate change may create unstable conditions around glaciers, GlacierHub recently covered this topic.
Uttarakhand Himalaya in northwest India is a rural, mountain region that shares borders with Nepal and Tibet. Often referred to as “The Land of Gods” for its physical grandeur, Uttarakhand is surrounded by some of the world’s highest peaks and glaciers. However, such beauty comes at a price. The Uttarakhand area is prone to natural and glacier-related disasters, often exacerbated by the region’s topography and climate patterns. Landslides, triggered by heavy rainfall and events called glacial lake outburst floods (GLOFs), expose the high mountain communities to infrastructure, life and community losses. A recent article by Naresh Rana Poonam et al. in Geomorphology measured and mapped susceptibility in Uttarakhand to help create a template that can be applied to locations facing similar climate-related landslides.
To conduct their research, Poonam et al. relied on Landslide Susceptibility Zonation (LSZ) mapping in order to deepen understanding and response in Uttarakhand to local hazards in a manner that can also be replicated elsewhere. Landslide Susceptibility Zonation (LSZ) is a type of mapping system that organizes different variables like geological, geomorphic, meteorological and man-made factors as high-risk based on the chances of slope failure. A slope failure occurs whenever a mountain slope collapses due to gravitational stresses, often triggering a destructive local landslide. Mapping these vulnerabilities is critical to understanding the dynamics and potential force of future landslides in the Himalayas and elsewhere.
Many of Uttarakhand’s peaks have year-round snowpack with glaciers and glacial lakes that can be disturbed by shifting rainfall patterns and changes in the onset of monsoon season. These disruptions can cause a destabilization deep within the ground, causing the initial movement needed to produce a landslide. Additionally, Uttarakhand’s proximity to the Indian Plate, a large tectonic plate where movement occurs along the boundaries, makes it especially vulnerable to frequent earthquakes. According to the United States Geological Survey, the last earthquake in Uttarakhand occurred on December 1, 2016, with a 5.2 magnitude. The energy released during an earthquake of that magnitude has the potential to trigger multiple, large-scale landslides.
Given the high-altitude location of Uttarakhand, earthquakes can also cause glacial lake outburst floods (GLOFs), a type of flood that occurs when the terminal moraine dam located at the maximum edge of a glacier collapses, releasing a large volume of water. These events can be especially destructive to rural mountain communities that are hard to access, making recovery efforts challenging and untimely. Additionally, these villages are often settled in areas where landslides naturally funnel. Preparing mountain communities to understand the risks they face is critical to minimizing damage associated with natural disasters. As a recent article in GlacierHub points out, “Educating and adapting ensures resilience to risks associated not only with glacial outburst flood risks, but also other risks associated with changing climates.” In an attempt to lower the risk of a landslide disaster triggered by a glacial lake outburst flood or rainfall event, Poonam et al. looked at ways to increase accuracy of floodplain mapping. The hope is to help increase the resiliency of communities by encouraging smart expansion with higher predictability of slide prone areas.
LSZ mapping is created using the Weights of Evidence method, a statistical procedure for calculating risk assessment using training data, like an established inventory of previous landslides. This statistical approach allows for information retrieved from a geographic information system (GIS) and remotely sensed data to be integrated regionally. LSV maps can also be derived from a knowledge-driven method that involves more human interpretation; however, this method is based on expert evaluations of a location. According to the article, the statistical approach is used more frequently because it lacks the subjective nature of the knowledge-driven method. When a location is evaluated by an expert, risks and interpretation of potential risks will differ based on the expert, leaving the risk of human error. The statistical approach provides consistency and confidence of regional LSZ maps because they can be interpreted using a common baseline.
The researchers hope that more precise mapping will help communities prepare for disasters such as the one that occurred in Uttarakhand in 2013. In a normal year, the monsoon rains soak Uttarakhand during the second week of July; however, in 2013, those rains arrived in June, a month earlier than expected, catching Uttarakhand off guard. During the spring months, water levels are high with snowmelt from rivers and glacial lakes. Combining monsoon rains with snowmelt during the spring can lead to devastating floods and landslides. As a result, 7,000 people and hundreds of animals lost their lives in a rainfall event on June 15th that took place in the Mandakini Valley, east of Nanda Devi National Park, according to BBC News. Adding to the devastating losses, the Manadkini Valley is also home to the Kedarnath Temple, where Hindu pilgrims travel between the months of May to October. The high volumes of people paired with the early-activated monsoon resulted in increased losses.
After experiencing the devastation of the landslides resulting from the June 2013 monsoon, many people thought the risk of staying in Uttarakhand was too high, so they relocated to the plains. The outmigration left 3,600 villages mostly deserted, as reported by Poonam et al. Outmigration due to climate-related disasters places mountain communities at additional risk for economic stagnation that may lead to increased forced migration to other areas.
Educating communities in both a scientific and social capacity on the risks associated with the natural interaction of weather and a geography allows for increased awareness among local populations which can help lead to better preparedness for future events. According to a recent GlacierHub article, the state of Jammu and Kashmir, located nearby, held a workshop to communicate risk to small mountain communities to help them understand and raise awareness into the unique risks associated with their location. Like with Uttarakhand, it’s not a question of if these events will happen, but when. Providing communities with detailed maps highlighting certain areas that are more prone to landslides and GLOFs will not eliminate the risk, but it may lower it. Combining LSV mapping with education programs on how to use the mapping information will provide small mountain villages with the future tools to build more sustainable and resilient communities. Since LSV mapping efforts are still being integrated, success may not be immediate. However, LSV mapping shows tremendous potential to enable people to continue residing in the world’s richly historic and picturesque locations.
Glaciers can play an important role in landscape dynamics, interacting with other factors to shape landscape development. Two days after a 7.8 magnitude earthquake struck North Canterbury, New Zealand, a landslide occurred between nearby Fox and Franz Josef glaciers. This landslide could offer insight into the role of glaciers in seismically active areas, particularly concerning the ways in which glaciers interact with earthquake-related instabilities in the landscape.
The landslide occurred at Omoeroa at around 2 p.m. (GMT +12 hours) on November 16th, closing off a section of State Highway 6 along the west coast of South Island for about three hours until debris were cleared.
Earthquakes and landslides are common in New Zealand due to the country’s location on the Pacific Ring of Fire, the area around the Pacific Ocean that is very seismically active. It is so named because of the prevalence of volcanic activity within the ring, which is made up by the major tectonic plate boundaries.
Earthquakes, which occur when Earth’s crust breaks along faults (fractures in the crust), send tremors outwards from the point of breakage. This particular earthquake was caused by oblique-reverse faulting (faulting that had both strike-slip and reverse components) near the boundary of the Pacific and Australian tectonic plates. Landslides, like the one that occurred between the two glaciers, are often triggered by other natural disasters, such as earthquakes or floods. In this case, the earthquake and its aftershocks triggered up to 100,000 landslides, causing local damage and blocking major roads and railway routes.
In conversation with GlacierHub, Umesh Haritashya, an associate professor in environmental geology at the University of Dayton, explained that the region in which the landslide occurred is prone to landslides even without any seismic activity. This is due to the topography of New Zealand’s Southern Alps. As such, it would not be surprising if the earthquake, landslide and glaciers are connected, he said.
While the two glaciers are found on the west coast of South Island, the earthquake occurred on the east coast of the island. The distance between the two suggests that the intensity of the tremors experienced in the area around the landslide may have been quite low. Nonetheless, a link is possible, according to Jeff Kargel, a geoscientist at the University of Arizona. “The timing of this big landslide is certainly suggestive of a direct link to the earthquake,” Kargel told GlacierHub.
“For both direct and circumstantial reasons, earthquakes, glaciers and landslides are closely associated,” Kargel explained. “There is the direct influence of glaciers that produce lots of unstable rock debris over thousands of years, and there are indirect influences, where glaciers erode the mountain topography and produce very steep slopes. These factors create conditions under which seismic activity can easily set off landslides.”
In addition, Kargel noted that glaciers occur where uplift rates have been high and the terrain is elevated to begin with. This means that either circumstantially or indirectly, glaciers and landslides can occur nearby.
Kargel further stated that large earthquakes tend to create instabilities in the landscape that are later exploited by natural processes, making landslides more frequent in the aftermath of earthquakes. “The spike in landslide activity can last for several years,” he said.
In addition to seismic activity, other causes like heavy rain after the earthquake could have contributed to the occurrence of the landslide. New Zealand’s MetService reported that the areas of the glaciers had received considerable rain, with 80-120mm falling the night after the earthquake.
“The West Coast receives an unusually high amount of rain, so slopes are already reconditioned and any seismic activity can trigger major landslides,” Haritashya explained.
The links between the earthquake, glaciers and landslides will become clearer as scientists examine similar events more fully. For now, landslides like these offer an insight into the complex interactions between glaciers, topography and seismic activity. Earthquakes can cause large amounts of disruption to people’s lives, so advancements in this field of science could prove valuable to communities as they seek to address the challenges posed by natural disasters.
This summer a 4,000-foot mountainside collapsed on the Lamplugh Glacier in Glacier Bay National Park in Alaska. Sightseeing and charter flight pilot Paul Swanstrom was the first to discover and photograph the massive landslide after he noticed a large cloud of dust over the glacier.
This region in Alaska is very geologically active and landslides are common there. However, Colin Stark, a geophysicist at Columbia University’s Lamont-Doherty Earth Observatory in New York, told Alaska Dispatch News that the movement of 130 million tons of earth was “exceptionally large.”
A recent geological study has shed some light on the cause of a major, yet elusive destructive natural hazard triggered by failed natural dams holding back glacial lakes. The findings show how previously unrecognized factors like thinning glacier ice and moisture levels in the ground surrounding a lake can determine the size and frequency of Glacier Lake Outburst Floods, or GLOFs.
The risks of these glacial floods are generally considered increasingly acute across the world, as warming atmospheric temperatures prompt ice and snow on mountain ranges to retreat and to swell glacial lakes.
The Landslides article is a step in understanding a previously understudied geological phenomenon. As little as five years ago scientists acknowledged the lack of research on the subject.
“We don’t really have the scientific evidence of these slopes breaking off and moraine stability… but personal observations are suggesting there are a lot of those…” said Ph.D. environmental historian Mark Carey in a 2011 video where he describes GOLFs.
Glacial Lake Outburst Flood risks do not always emanate from mountain glacier meltwater that flows downstream. As this study shows, in some instances, trillions of gallons of water can be trapped by a moraine, a formation of mixed rock, which forms a natural dam. A weakening over time, or a sudden event, such as a landslide, could then result in the moraine dam’s collapse.
The massive amount of water is suddenly then released, and a wall of debris-filled liquid speeds down the mountainside with a destructive force capable of leveling entire city blocks.
GLOFs have presented an ongoing risk to people and their homes dating back to 1703, especially in the Cordillera Blanca region, according to United States Geological Survey records. In December of 1941, a breach in the glacial moraine restraining Palcacocha Lake led to the destruction of a significant portion of the city of Huaraz and killed approximately 5,000 people.
Scientists and government agencies, like the Control Commission of Cordillera Blanca Lakes created by the Peruvian government following the 1941 GLOF, have recognized the need to better understand and control GLOFs. The study found that as global temperatures rise and glaciers retreat, greater amounts of glacier melt water will continue to fill up mountain lakes, chucks of ice will fall off glaciers, and wetter moraines will become more prone to landslides.
The team of mostly Czech geologists and hydrologists (J. Klimeš; J. Novotný; I. Novotná; V. Vilímek; A. Emmer; M. Kusák; F. Hartvich) along with Spanish, Peruvian and Swiss scientists (B. Jordán de Urries; A. Cochachin Rapre; H. Frey and T. Strozzi) investigated the ability of a glacial moraine’s slope to stay intact, called shear strength, and modeled the potential of landslides and falling ice to cause GLOFs.
After extensive field investigations, calculations and research into historical events, the study found several causal factors that can determine the severity of a GLOF. These include size and angle of entry of a landslide, shape and depth of the glacial lake, glacier thickness and human preventative engineering such as canals and supporting dams. Frequency and size of a landslide is determined by the stability of surface material, a characteristic called shear strength, which can be influenced by something as subtle as the crystalline shape of the predominant mineral in the rock.
The scientists determined that waves caused by moraine landslides and falling ice would most likely lead to over-toppings of the natural dam. An example would be the 2003 Palcacocha Lake GLOF, which was caused by falling ice. No one died in this flood, but sediment from the floodwaters blocked the Huaraz’s main water treatment facility, leaving 60 percent of the population without drinking water for six days. Additionally, small events like the one in 2003 weaken the natural and manmade dams, which without monitoring could eventually give out and result in a more catastrophic occurrence.
Most recent measurements estimate Palcacocha Lake holds 4.5 trillion gallons of glacier meltwater, which is enough to fill approximately 6,800 olympic size pools. The potential of a catastrophic flood following the collapse of the moraine dam is a serious threat to the growing city that lies beneath it. “Climate-driven environmental changes may critically affect stabilities of slopes above glacial lakes, possibly triggering large moraine landslides,” write the authors in the article. They call for continued monitoring of glacial lakes.
“The chapter looks mainly at massive rock slope failures that generate high-speed, long- runout rock avalanches onto glaciers in high mountains, from subpolar through tropical latitudes. Drastic modifications of mountain landscapes and destructive impacts occur, and initiate other, longer-term hazards. Worst-case calamities are where mass flows continue into inhabited areas below the glaciers. Travel over glaciers can change landslide dynamics and amplify the speed and length of runout.”
“According to research accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union, the underwater noise levels are much louder than previously thought, which leads scientists to ask how the noise levels influence the behavior of harbor seals and whales in Alaska’s fjords.”
“High temporal resolution measurements of black carbon (BC) and organic carbon (OC) covering the time period of 1956–2006 in an ice core over the southeastern Tibetan Plateau show a distinct seasonal dependence of BC and OC with higher respective concentrations but a lower OC / BC ratio in the non-monsoon season than during the summer monsoon. We use a global aerosol-climate model, in which BC emitted from different source regions can be explicitly tracked, to quantify BC source–receptor relationships between four Asian source regions and the southeastern Tibetan Plateau as a receptor.”
Along Georgia’s border with Russia, about two hours north of the Georgian capital of Tbilisi, the Tergi River flows on an almost 400 mile journey down from the Devdorak Glacier atop Mount Kazbek to the Caspian Sea. The river has been a valued source of water for the communities along its banks for thousands of years, and the gorge which it cuts through the Caucasus has been a key trade route as well.
It has recently become the site of a controversial hydroelectric project. After not one, but two major landslides, the Dariali Hydropower Plant, located on the river, has become a topic of recent debate. The May 2014 landslide left three power plant workers dead and five others missing, it also completely impeded the Dariali Gorge, cutting of the region’s arterial roadway between Georgia and Russia, in addition to severing an essential natural gas pipeline providing Armenia with natural gas from Russia. The August landslide, reportedly larger than the one a few months before, resulted in the death of two more hydroelectric plant workers and necessitated a visit to the area by the Georgian president.
These events are not new for the region, which has been blighted by landslides for as long as local history remembers. This history makes local residents concerned. Other hydroelectric projects have succumbed to such hazards. For this reason and others ,the Dariali project, which would provide an estimated 108 Megawatts of electricity to the region, has already run into political controversy. The public does not fully accept the project, Eighty to 90 percent of the Tergi River would have to be diverted, leaving almost five miles of the riverbed completely dry, and threatening the local trout population. The project necessitated the rezoning of the area, removing its status as a national park under legal protection. Local people were concerned that construction began before a permit was issued, or before even mandatory public hearings were held.
Another issue is contribution of global warming to the latest two landslides. Devdorak Glacier, like other glaciers in the Caucasus, has been retreating in recent years. The meltwater could lead to increased water flow and thus contribute to natural erosion, increasing the risk of floods and landslides. Such dangers are well-established in the valley, as demonstrated by accounts as far back as 1869. Douglas W. Freshfield gives this account in his “Travels in the Central Caucasus and Bashan“:
“M.E. Favre, of Geneva, a well-known geologist who visited the Devdorak Glacier a few weeks after ourselves, came to the following conclusion as to the nature of the catastrophe. No avalanche, he says, could without the aid of water traverse the space between the end of the glacier and the Terek (Tergi river), and he accounts for the disasters which have taken place in the following way. He believes the Devdorak Glacier, to which he finds a parallel in the Vernagtferner Glacier in the Ötzthal Alps, to be subject to periods of sudden advance. During these the ice finds no sufficient space to spread itself out in the narrow gorge into which it is driven, and is consequently forced by the pressure from behind into so compact a mass that the ordinary water-channels are stopped, and the whole drainage of the glacier is pent-up beneath its surface. Sooner or later the accumulated waters burst open their prison, carrying away with them the lower portion of the glacier. A mingled flood of snow and ice, increased by earth and rocks torn from the hillsides in its passage, sweeps down the glen of Devdorak. Issuing into the main valley it spreads from side to side, and dams the Terek. A lake is formed, and increases in size until it breaks through its barrier, and inundates the Dariali Gorge and the lower valley.” [ed: place names have been modernized from original text]
Only time will tell whether or not the Dariali Hydropower Plant will be realized, and if so, what the effects will be for the region. Looking back at recent history, however, the safety of the project itself and the valley below seems suspect at the least.
For more information about the Dariali Gorge landslide see: