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ONE PLANET MANY PEOPLE Atlas of Our Changing Environment

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ONE PLANET MANY PEOPLE Atlas of Our Changing Environment ONE PLANET MANY PEOPLE Atlas of Our Changing Environment i Credit: Olga Tutubalina/UNEP Mount Dzhimarai-Khokh, elevation 4 780 metres (15 682 feet), towers above the Kolka Cirque. Rock and ice falling from the steep walls of the cirque since 13 June 2001 the end of July 2002, eventually triggered the collapse of the Kolka Glacier. NASA Image by Jesse Allen and Robert Simmon based on MODIS data Case Study: Collapse of the Kolka Glacier of rock and hanging glacier on the north lakes upstream. Boulders, pebbles, and 20 September 2002 face of Mt. Dzhimarai-Khokh tumbled onto mud covered the surface of the debris fl ow, the Kolka glacier below. Kolka shattered, resulting in treacherous footing. The path- Rebecca Lindsey, Olga Tutubalina, Dmitry setting off a massive avalanche of ice, snow, less maze of debris was only one of many Petrakov, Sergey Chernomorets and rocks that poured into the Genaldon hazards that slowed exploration of the River valley. Hurtling downriver nearly 13 disaster area. Running east to west across the narrow km (8 miles), the avalanche exploded into Scratches on the surface of rocks of the isthmus of land between the Caspian Sea the Karmadon Depression, a small bowl Maili Glacier’s moraine show the violence to the east and the Black Sea to the west, of land between two mountain ridges, and of the event. The avalanche, moving up the Caucasus Mountains make a physical swallowed the village of Nizhniy Karmadon to 180 kilometres per hour (112 mph), barricade between southern Russia to the and several other settlements. scoured the rocks below, leaving parallel north and the countries of Georgia and At the northern end of the depression, grooves called “striations.” Striations are Azerbaijan to the south. In their center, the churning mass of debris reached a typically observed in the bedrock underly- a series of 5 000-metre-plus (16 000-feet- choke point: the Gates of Karmadon, the ing glaciers, created by the slow, scouring plus) summits stretch between two extinct narrow entrance to a steep-walled gorge. action of rocks caught beneath the ice. volcanic giants: Mt. Elbrus at the western Gigantic blocks of ice and rock jammed Large-scale avalanches and glacial col- limit and Mt. Kazbek at the eastern. On the into the narrow slot, and water and mud lapses are not uncommon on the slopes lower slopes, snow disappears in July and sluiced through. Trapped by the blockage, of Mount Kazbek and nearby peaks. The returns again in October. On the summit, avalanche debris crashed like waves against Kolka Glacier collapsed in 1902, surged winter is permanent. Glaciers cover peaks the mountains and then fi nally cemented in 1969, and collapsed again in 2002. and steep-walled basins into a towering dam of dirty ice and rock, Evidence, including historical accounts, called cirques. The remote, sparsely creating lakes upstream. At least 125 indicates similar events have happened in populated area is popular with tourists people were lost beneath the ice. neighboring valleys as well. and backpackers. The Kolka Glacier collapse partially After the collapse, people speculated Elevations reach 5 642 metres (18 511 fi lled the Karmadon Depression with ice, that something called a glacial surge had feet), and glaciers accumulate from heavy mud, and rocks, destroying much of the triggered the Kolka collapse. In 1902, a snowfall in the steep mountain valleys. village of Karmadon. The debris swept in more signifi cant collapse at Kolka Glacier Around Mount Kazbek, a dormant volcano, through the Genaldon River Valley and killed 32 people. Despite a history of disas- glaciers intermittently collapse, burying backed up at the entrance to a narrow ters there, routine monitoring of the Kolka the landscape below under rock and ice. gorge. The debris acted as a dam, creating Glacier cirque ended in the late 1980s. The latest of such collapses happened in 2002. Rebecca Lindsey, science writer with 19 October 2002 22 May 2003 11 July 2003 30 August 2003 NASA’s Earth Observatory, in close collabo- ration with Russian scientists Olga Tutubali- na, Dmitry Petrakov (Moscow State Univer- sity), and Sergey Chernomorets (University Centre for Engineering Geodynamics and Monitoring) compiled the details of this event. On the evening of 20 September 2002, in a cirque just west of Mt. Kazbek, chunks This sequence of images from the Indian Remote Sensing (IRS) satellites showed that the lakes (except Lake Saniba) were draining gradually through crevasses in the ice mass, and were not likely to cause subsequent catastrophic fl oods. Credit: IRS 266 Credit: Sergey Chernomorets/UNEP The rapidly rising water was a continuing a large remnant of the Kolka Glacier, ice fumaroles—volcanic vents—on the face of danger, threatening a sudden outburst that cliffs high above the fl oor of the cirque, Mount Dzhimarai-Khokh in the area where would cause fl ooding downstream. displaced porous ice, the Maili Glacier, a the hanging glacier collapsed. Russian researchers evaluated the risk temporary lake, and deposits of rubble left Based on the available data and obser- of future danger at the disaster site using a along the path of the collapsing glacier. vations, the scientists say they don’t expect time-series of satellite images collected in There is uncertainty also about what any additional catastrophic processes with- the year following the disaster. Satellite im- triggered the collapse of rocks and hang- in the next 10 to 20 years. The remaining agery was crucial throughout the late fall ing glaciers on Mount Dzhimarai-Khokh. lakes will likely continue to drain through and winter of 2002 and 2003, when dan- Two small earthquakes jarred the region in crevasses and channels being cut through gerous weather prevented on-site observa- the months before the collapse, probably the ice mass, and as they drain, the risk of tions of the ice-dammed lakes. destabilized the hanging glaciers. In the fl ooding decreases. Russian scientists combined satellite fi rst days after the collapse, an Emercom data with ground observations to create (Russian Emergencies Ministry) crew fl ew Published 9 September 2004 maps of the Kolka Glacier Cirque. The to the site via helicopter, but was forced to Source: http://earthobservatory.nasa.gov/Study/Kolka/ kolka.html IRS Satellite image (acquired 11 July evacuate immediately when the crew de- 2003) shows details of the cirque, includ- tected an overpowering smell of sulfur-con- ing scars caused by post-collapse rockfall, taining gas. It seems there may be some Credit: Digital Globe The area covered by ice and debris dwarfed the hamlet of Karmadon, and the Genaldon River disappeared completely. (The outline corre- sponds to the detailed image above.) 25 Sept 2002 Credit: Olga Tutubalina, Dmitry Petrakov, Sergey Chernomorets/UNEP 267.
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