periglacial hazards

Question 1

what is the classification of clod region hazards?

Answer 1

ground instability impact and burial- snow avalanches and permafrost. few fatalities but economic costs are very high and it is increasing.

Question 2

what are factors that enhance the potential hazardousness of permafrost?

Answer 2

irregular permafrost distribution
high permafrost temperature
high ice ground content
thick, moist active layer 
steep slopes

Question 3

what are factors that enhance human risk to permafrost hazardousness?

Answer 3

high population density and vulnerability
valuable infrastructure located on permafrost
inadequate engineering regulation

Question 4

what is periglacial?

Answer 4

cold but not glacial- ground ice rather than glaciers.

Question 5

what is permafrost?

Answer 5

physical state. the more you build on it, the more hazardous.

Question 6

what layers do permafrost consist of?

Answer 6

active layer and permafrost, plus unfrozen areas called talik.

Question 7

what are the main types of permafrost?

Answer 7

continuous, discontinuous, and sporadic and isolated.

Question 8

what percentage of frozen is continuous?

Answer 8

90-100% frozen

Question 9

what percentage of frozen is discontinuous?

Answer 9

50-90% frozen

Question 10

what percentage of frozen is sporadic?

Answer 10

10-50% frozen

Question 11

what percentage of frozen is isolated?

Answer 11

0-10% frozen

Question 12

why are snow avalanches so dangerous?

Answer 12

due to velocity, shortness of time between initiation and impact etc

Question 13

what is the density core like in an avalanche?

Answer 13

from 50 to 100 km/m cubed. consist of dense avalanche core and suspension layer

Question 14

how do you measure the speed of avalanches?

Answer 14

hard to measure. related to the amount of vertical fall and wetness of snow.

Question 15

how are avalanches classified?

Answer 15

according to: 
triggering mechanism
type of rupture
position of sliding surface
humidity

Question 16

what are the 2 main types of avalanches?

Answer 16

lose snow, and slap-avalanche

Question 17

what are the 2 main controls of snow avalanches?

Answer 17

meteorology and terrain

Question 18

how does meteorology control avalanches?

Answer 18

how much snow, where it falls, where snow accumulates. what happens after fall by changing temperature and moisture that can change crystal structure and snowpack stability.

Question 19

how does terrain control avalanches?

Answer 19

slope angle, aspect, roughness (trees etc)

Question 20

what are the impacts of snow avalanches on infrastructure?

Answer 20

breaks windows, push in doors, destroys wood-framed structures, uproots mature spruce trees, move reinforced concrete structures.

Question 21

what are mitigation measures of avalanches?

Answer 21

mapping and hazard zoning, terrain engineering, avoidance and evacuation

Question 22

how can you live with avalanches?

Answer 22

permanent snow supporting structures
temporary snow supporting structures
snow drift measures
avalanche dams
direct protection of buildings
forest

Question 23

what are examples of direct protection of buildings?

Answer 23

avalanche splitter and reinforced walls.

Question 24

what are examples of avalanche dams?

Answer 24

catching dams, deflecting dams, breaking mounds.

Question 25

what are examples of snow drift measures?

Answer 25

fences, and wind baffles.

Question 26

what are permafrost hazards?

Answer 26

bedrock and sediments.

Question 27

what is bedrock?

Answer 27

non-competent lithologies, competent well joined lithologies, competent massive lithologies.

Question 28

what is sediment?

Answer 28

fine grained and corse-grained.

Question 29

what are triggers for permafrost degradation and hazards?

Answer 29

vegetation (human and natural), climate, geomorphology.

Question 30

what happens when ground ice melts in permafrost?

Answer 30

active layer thickens, ground ice melts, ground subsides organic matter frozen in permafrost begins to bet and release greenhouse gases.

Question 31

why does permafrost melt?

Answer 31

when ice rich permafrost melts, there will be a loss of volume. ground stability decreases even with partial melt and permafrost warming.

Question 32

what are key factors of permafrost melting?

Answer 32

low altitude, frequency of large flood plains, areas of relatively high population.

Question 33

what are types of management for lowland periglacial hazards?

Answer 33

hazard mapping, geotechnical engineering, thermosyphons, piling, insulation.

Question 34

what fraction of the world does permafrost cover?

Answer 34

1/4

Question 35

why are highland events increasing and becoming more extreme?

Answer 35

due to the nature and consequences of periglacial hazards reflecting the amount of energy released.

Question 36

what holds a crucial role in determining the temperature and moisture drivers of all relevant periglacial processes?

Answer 36

seasonality.

Question 37

what is permafrost?

Answer 37

permafrost is ground, including rock or (cryotic) soil, with a temperature that remains at or below the freezing point of water 0 °C (32 °F) for two or more years.

Question 38

where is permafrost located?

Answer 38

Most permafrost is located in high latitudes (in and around the Arctic and Antarctic regions), but at lower latitudes alpine permafrost occurs at higher elevations.

Question 39

is ground ice always in permafrost?

Answer 39

Ground ice is not always present, as may be in the case of non-porous bedrock, but it frequently occurs, and it may be in amounts exceeding the potential hydraulic saturation of the ground material