glacial hazards Flashcards
what are glaciers?
the build-up of snow turning into ice, as it flows down the hills. movement of ice.
what are the walking dangers with glaciers?
the weight of the glacier moves the whole thing forwards. crevasses, and ice falls and seracs (blocks of ice)
how is an ice avalanche formed?
as glaciers retreat back, glaciers can separate.
what happened in 1965?
88 workers were buried by an ice avalanche in Allalin Glacier. they trigger snow avalanches or combined with outburst floods. warm events can cause the glaciers to slip.
what is the mitigation for glaciers?
monitoring, hazard maps, evacuation plans. soft measures may include engineering. potential GLOFS, increasing awareness, observing and forecasting.
what are lahars?
snow and ice melt by lava, a pyroclastic flow.
what are the hazards with glacial floods?
damage to infrastucture and economic costs.
what does GLOF stand for
glacial lake outburst floods
what can earthquakes trigger?
ice avalanches, and cause GLOFS, and initiate lahars.
what happened in Eyjafjallajokull?
the eruption, ice caps melted. 700 people evacuated. destroyed main roads, 20 farms destroyed. closure of air spaces for 5 days.
when was Eyjafjallajokull case study?
2010
what happened in Grimsvotn?
eruption of subglacial volcano. melting of the ice cap and draining of lake Grimsvotn. 3.2 km cubed drained in 40 hours. flow as high as 40,000m cubed per second. no loss of life but damage.
when was Grimsvotn?
1996
what happened in Sabai Tsho?
warm wet monsoon, increase lake depth and increased velocity. 3 small earthquakes, cause the waves, collapse of the moraine. millions of fo water and lowered the lake surface by 30m.
when was Sanai Tsho?
1998
what are the hazards of GLOFs?
they carry a significant amount of debris downstream, altering the geomorphology.
what triggers GLOFs?
avalanche displacement. causes ice avalanches, glacier calving, collapse of hanging valleys, valley side rck falls, debris, earthquakes.
what are icebergs?
a large piece of freshwater ice that has broken off a glacier or an ice shelf and is floating freely in open water.
what are the hazards with icebergs?
direct impact with ships or installments. sea bed scours as well as scraping along with ocean flood. disruption of ecological systems.
what is the mitigation for icebergs?
visual and satellite reconnaisance. immobile structures neede to divery the iceberg. towing and water cannons.
how is climate change affecting glaciers?
increased risk of GLOFs. creaing more moraine dammed lakes which could fail. debris flows increases. moraine damns accelerated degradation through melting of ice cores. sea levels rise, water shortages, hydroelectrical power, glacial retreat leading to volcanic activity.
when was the last interglacial?
120 thousand years ago.
