How different hazards occur

Question 1

Where do EQ’s occur?

Answer 1

On plate boundaries

Question 2

Define plate boundary

Answer 2

Where different plates meet

Question 3

What is a plate?

Answer 3

Areas of land that the lithosphere is divided up into.

Question 4

How do EQ’s occur at destructive plate boundaries?

Answer 4

Subduction
Range of EQ types
Pressure compressing as they meet suddenly releasing focus
Epicentre
C & O, C&C, O&O
Fold mountains
Shallow high damage

Question 5

How do EQ’s occur at constructive plate boundaries?

Answer 5

Shallow, low magnitude
Magma rises
Most submarine so little risk to people

Question 6

How do EQ’s occur at conservative plate boundaries?

Answer 6

Frequent shallow
Sometimes high mag
EQ within plate
From stress on land due to dam/reservoir building

Question 7

What are the primary impacts of EQ’s?

Answer 7

Ground movement, seismic waves, collapsing infrastructure

Question 8

What are the secondary impacts of EQ’s?

Answer 8

Soil liquefaction, landslides, avalanches, tsunamis

Question 9

How do volcanoes occur at constructive boundaries?

Answer 9

Shield - thin, runny, frequent, gentle
Mostly at oceanic ridges
Mostly on sea floor so not major hazard unless they emerge above sea level to form island = more dangerous

Question 10

How do volcanoes occur at destructive boundaries?

Answer 10

80% in Ring of Fire
At subduction zones
Composite - pyroclastic, lava & ash, hot, viscous, dangerous

Question 11

Define mid ocean ridge

Answer 11

Seismically active submarine ridge system in the middle of ocean basin where there is upwelling magma

Question 12

Define Ring of Fire

Answer 12

Area in Pacific Ocean basin where many EQ’s & volcanic eruptions occur

Question 13

Define Hotspot

Answer 13

Localised area of Earth’s Crust with unusually high temperature

Question 14

Define pyroclastic flow

Answer 14

Destructive dense mass of hot ash, lava, gas ejected explosively from a volcano and quickly flowing

Question 15

Define magma

Answer 15

Molten material rising towards Earth’s surface when hotspots in asthenosphere generate convection currents

Question 16

What are the impacts of volcanoes?

Answer 16

Lava flows, pyroclastic flows, ash falls, tsunami, mudflows

Question 17

What increases the chance of a landslide?

Answer 17

In mountainous areas, where there is heavy rain, seismic areas, deforestation increases chance

Question 18

What increases the chance of a snow avalanche?

Answer 18

Mountainous
Slopes steeper than 35 degrees
Global warming

Question 19

What are the causes of drought?

Answer 19

Variations in movement of the ITCZ
El Nini
Mid latitude depression track changes
Anticyclones

Question 20

Define ITCZ

Answer 20

Inter-tropical convergence zone - area of low pressure as northeasterly & southeasterly winds converge over the equator forming clouds and frequent heavy showers

Question 21

Define mid-latitude depression tracks

Answer 21

Where sub-tropic warm air meets polar cold air creating low pressure = rainfall/cyclones

Question 22

What are the causes of flooding?

Answer 22

Series of depressions
Monsoon cyclones
Flash floods
El Nino
Rapid snowmelt adding water to already swollen river systems

Question 23

What are the causes of storms?

Answer 23

Tropical cyclones
Tornadoes
Mid latitude storms

Question 24

What are the hazards that occur as a result of storms?

Answer 24

High wind velocity
Storm surges
Coastal flooding
Flood
Mudslides

Question 25

Which hazards are hydrometeorological?

Answer 25

Drought
Flooding
Storms

Question 26

Which hazards are geophysical?

Answer 26

EQ

Volcanoes

Question 27

Which hazards are geophysical and hydrometeorological?

Answer 27

Landslides

Snow avalanches

Question 28

How do tornados occur?

Answer 28

Develops from a supercell with areas of rotation in the cloud
Large down draughts drag part of cloud down creating a condensation funnel.
Vortex becomes in contact with the ground and cloud base so classified as a tornado.