Hazards

Question 1

what are geophysical hazards?

Answer 1

volcanic and seismic hazards related to the lithosphere

Question 2

what are atmospheric hazards?

Answer 2

includes tropical storms, droughts and tornadoes . Hazards related to the atmosphere

Question 3

what are hydrological hazards?

Answer 3

involve flooding and are related to the hydrosphere

Question 4

what is risk?

Answer 4

the potential for loss

Question 5

what is vulnerability?

Answer 5

the exposure to hazards and ability to cope with them

Question 6

what is resilience?

Answer 6

the degree to which a population or environment can absorb a hazardous event

Question 7

what are features that increase resilience?

Answer 7

• emergency evacuation, rescue and relief systems in place
• helping each other/ community
• having a hazard resistant design or land use planning

Question 8

why is it difficult to compare impacts between countries?

Answer 8

• the physical nature of the event is different
• the socio-economic characteristics of places are different
• economic costs in developed economies are large, but they are less costly in developing countries
• deaths in developed countries are lower

Question 9

what are influences of vulnerability?

Answer 9

inequality of access to education, housing, healthcare, income

Question 10

what is the fatalist approach to a hazard?

Answer 10

where people accept the risk and choose to do little about it. More likely in developing countries/LICs

Question 11

what is a destructive plate margin?

Answer 11

when oceanic plate slides beneath continental plate and crust is destroyed as one goes beneath the other towards the subduction zone

Question 12

what is a conservative plate margin?

Answer 12

plates sliding past each other horizontally

Question 13

what is a constructive plate margin?

Answer 13

plates move apart from each other

Question 14

characteristics of oceanic plate?

Answer 14

• high-density
• made of basaltic rock
• 7-10km thick
• subduct beneath other plates

Question 15

characteristics of continental crust?

Answer 15

• 25-75km thick
• less dense
• granite- do not sink

Question 16

what is an island arc?

Answer 16

• form at destructive subduction boundaries, when the descending plate melts and material rises towards the surface as magma
• when plutons of magma reach the surface they form volcanoes which may erupt offshore, causing al ine of volcanic islands eg. Marianas trench

Question 17

what are volcanoes?

Answer 17

• found at constructive and destructive subduction boundaries, where the melted plate rises to the surface

Question 18

what are deep sea trenches?

Answer 18

• found at destructive subduction boundaries, where oceanic subducts under continental eg. Marianas trench

Question 19

what are fold mountains?

Answer 19

• destructive subduction and destructive collision boundaries
• as plates move together, sediment in the sea is pushed up into folds between them

Question 20

what are rift valleys?

Answer 20

• formed at constructive plate boundaries where 2 continental plates pull apart
• as the crust thins it is heated forming cracks
• when an area of crust drops down between two parallel faults this is a rift valley

Question 21

what are ocean ridges?

Answer 21

• formed at constructive boundaries where 2 oceanic plates pull apart
• as pressure is reduced the semi-molten magma of the mantle melts and rises up into the gap between the plates forming a ridge eg. mid-Atlantic

Question 22

what is a hazard?

Answer 22

a natural event that has the potential to threaten both life and property

Question 23

what is the distribution of hazards like?

Answer 23

uneven- some areas of the world are at low risk some are at high risk
- distribution of earthquakes is uneven- pacific ring of fire mainly

Question 24

what are hotspots?

Answer 24

• a hot mass or rising heat under a weakness in a plate

- magma rises to the surface through the weaknesses

Question 25

what is the lithosphere?

Answer 25

the crust and upper mantle (80-90km) which form the tectonic plates

Question 26

what is the mantle?

Answer 26

the mantle is a semi molten body of rock between the earth's crust and its core

Question 27

what is the core?

Answer 27

the central part of the earth

Question 28

what is the asthenosphere?

Answer 28

lower part of the mantle

Question 29

what is gravitational sliding?

Answer 29

elevated altitudes of oceanic crust at ridges at divergent plate boundaries- creating a slope down which oceanic plates slide

Question 30

what is sea floor spreading?

Answer 30

- in the 1960s, there was a discovery of magnetic stripes in the oceanic crust of the seabed - paleomagnetic signals from past reversals of the Earth's magnetic field prove that new crust is created by the process of seafloor spreading at mid-ocean ridges

Question 31

what is slab pull?

Answer 31

at convergent boundaries, high density ocean floor is being dragged down by a downward gravitational force beneath the adjoining continental crust

Question 32

what did Wegner say about continental drift?

Answer 32

1912- said that our now separate continents had once been joined together as super continents eg. Pangea

Question 33

what happens at a collision margin?

Answer 33

characterised by the meeting of two continental landmasses resulting in the formation of a fold mountain belt

Question 34

what happens at a transform margin?

Answer 34

- no volcanic activity

Question 35

what is pyroclastic and ash fallout?

Answer 35

- any material that has been ejected from a volcano and has travelled through the air and fallen onto earth

Question 36

what are pyroclastic flows/nuees ardentes?

Answer 36

- currents of hot ash, lava and gas that move downhill during an eruption

Question 37

what are lahars?

Answer 37

- if volcanic ash or lava mixes with water lahars (mudflows) form - fast moving flows of volcanic material and water

Question 38

what is tephra?

Answer 38

- rock fragments that are ejected from the eruption

Question 39

how can you predict volcanic eruptions?

Answer 39

- gas emissions - seismic waves - thermal images (magma) - volcanic swelling

Question 40

what is a jokulhlaup?

Answer 40

the name of the flooding that happens when glaciers or ice caps melt

Question 41

what are immediate responses to an eruption?

Answer 41

- aid - evacuation - warnings and monitoring - temporary infrastructure

Question 42

what are the long term responses to volcanic eruptions?

Answer 42

- education - improve local economy - rebuild infrastructure - relocation

Question 43

what are effective mitigation and adaptation strategies?

Answer 43

- physical defences - land-use and buildings- resistant infrastructure- land use zoning - community preparedness and education - modifying loss- aid/compensation

Question 44

what is the focus?

Answer 44

where the pressure is released underground and where the energy radiates from

Question 45

what is the epicentre?

Answer 45

the point above ground directly above the focus

Question 46

what are the 3 types of EQ?

Answer 46

- shallow focus-0-70km beneath surface - deep focus- 70-700km- less damaging - underwater EQs- move the seabed causing water to be displaced

Question 47

what are the primary hazards of EQs?

Answer 47

- ground shaking | - crustal fracturing- earth splitting apart

Question 48

what are the secondary hazards of EQs?

Answer 48

- landslides - liquefaction - tsunamis

Question 49

how is a tsunami created?

Answer 49

the seabed is displaced vertically- this motion displaces a large volume of water in the ocean column which then moves outwards from the point of displacement

Question 50

what is a collision plate margin?

Answer 50

- two continental plates move together= fold mountains

Question 51

how do you mitigate against the impact of EQ's?

Answer 51

- physical defences - education - land-use and buildings - EQ proof buildings - alert system

Question 52

what causes a tropical storm?

Answer 52

- warm air rising from oceans with over 27° will create pockets of low pressure. These will draw in warm air from the surrounding area - if this occurs between 5-20° N or S of equator the Coriolis force means these systems will rotate - as more warm air is drawn in, they grow into tropical depressions and eventually tropical storms

Question 53

what is the structure of a tropical storm?

Answer 53

- 200-700km wide with rotating spiral of clouds - eye usually 10-15km in diameter- calm - strong conditions in eye wall - energy dissipates over ground

Question 54

what hazards are associated with tropical storms?

Answer 54

- heavy rainfall - storm surges - strong winds

Question 55

how are storms measured?

Answer 55

on the saffir-simpson scale- largest storms reaching category 5

Question 56

how frequent are tropical storms?

Answer 56

- around 100 tropical storms form in the Atlantic each year with 5.9 becoming hurricanes - frequency increase linked to global warming