Geophysical Hazards

Question 1

Geophysical Hazards

Answer 1

‘Earth Processes’ = volcanic eruptions, earthquakes, mass movements that threaten; loss of life/injury, property damage, social and £ disruption, enviro degradation.

Question 2

Continental drift theory

Answer 2

Continents have drifted over time.

Question 3

Lithosphere

Answer 3

Rocky outer layer of the earth (the crust and upper part of the mantle) brittle and solid, where most tectonic activity occurs.

Question 4

Asthenosphere

Answer 4

100-410km beneath earths surface, semi- molten due to high temp and pressure , ductile and viscous, layer associated with continental drift

Question 5

Transition zone

Answer 5

410-660km, rocks are crystalline (more dense) which is paradoxical due to extreme pressure

Question 6

Lower mantle

Answer 6

660-2700km, hotter and denser than transition zone

Question 7

Earths cores

Answer 7

Hottest part, drives convection movement above,

Question 8

Where does the heat come from ?

Answer 8

Radioactive decay - radioactive elements in the core breakdown = generating heat.
Residual heat from the Big Bang

Question 9

Convergent

Answer 9

Towards eachother

Question 10

Divergent

Answer 10

Away from eachother

Question 11

Subduction

Answer 11

At convergent plates, oceanic lithosphere collides with another plate and is forced to sink into mantle, and drags the rest of the plate with it.

Question 12

Rifting

Answer 12

The splitting apart of a single plate into two or more plates, separated by divergent boundaries

Question 13

Slab pull

Answer 13

Where the older, denser plate sinks into the mantle and is pulled along. The sinking in one plate leads to the separating of a plate in another place.

Question 14

Cinder cone volcano

Answer 14

Formed from congealed lava ejected from a single vent, violent

Question 15

Composite volcano

Answer 15

At destructive plate margins, steep sides (lave doesn’t flow very far, solidifies) alternate layers of ash and lava, violent, lava very viscous.

Question 16

Shield volcano

Answer 16

Constructive margins, gentle sides ( lave flows a long distance) no layer, no- violent

Question 17

Landslides

Answer 17

Large masses of wet or dry risk and soil that fall under the force of gravity ( can transform into a lahar)
Common at volcanic cones, tall, steep, and weakened by the rise and eruption of molten rock.
Magma also releases gas that partially dissolves in water - weakening rock
The fast velocity and great momentum allows them to cross valley divides and run up slopes.

Question 18

Lahars

Answer 18

Hot or cold mixture of water and rock fragments that flow doesn’t volcano slopes, generally composite.
Size, speed and amount carried can constantly change - incorporates buildings, risk and soil.
Commonly gore 10x their original size
Can exceed 200km/hr