Hazards: EGC All Quizlet

Question 1

Accretion Wedge

Answer 1

The accumulation of material at the point of subduction.

Question 2

Acid rain

Answer 2

Volcanoes emit sulphurous gases, which can result in acidic rainwater when combined with atmospheric moisture.

Question 3

Adaption

Answer 3

If we accept that natural events are inevitable, we can adapt/make changes to increase the level of protection and reduce risks. This may include making changes to the built environment

Question 4

Alfred Wegener

Answer 4

Published a theory in 1912 suggesting that there was once one supercontinent called Pangea and that over time the landmasses drifted apart until they reached their current positions. His theory was based on a range of evidence, including geological, climatological and biological. He could not explain how continental movement could have taken place.

Question 5

Aseismic Buildings

Answer 5

Buildings designed to withstand or minimise destruction during an earthquake.

Question 6

Ash

Answer 6

Fine particles and dust ejected during an eruption, which can remain airborne as clouds or accumulate on the ground.

Question 7

Ash fall

Answer 7

Ash can be ejected high into the atmosphere and can cover a large area. Ash is highly abrasive, is heavy when it accumulates in layers and can obstruct sunlight

Question 8

Asthenosphere

Answer 8

The upper mantle layer of the Earth. It is semi-molten and approximately 2000km wide.

Question 9

Atmospheric hazards

Answer 9

Driven by processes at work in the atmosphere e.g., tropical storms, droughts

Question 10

Benioff Zone

Answer 10

The area where friction is created between two plates as a result of subduction at a destructive plate margin

Question 11

Body Waves

Answer 11

Shockwaves that travel through the earth

Question 12

Collision plate margins

Answer 12

These occur where two continental plates converge (move together). This results in the plates buckling up and faulting and in the formation of young fold mountains.

Question 13

Community Risk Sharing

Answer 13

One way of reducing people’s vulnerability. It involves public education and awareness programmes. It may include evacuation procedures and shelters as well as insurance (in richer areas).

Question 14

Conservative plate margins

Answer 14

These occur where two plates rub past each other or are side by side moving in the same direction but at different speeds. Earthquakes are a feature of these margins.

Question 15

Constructive plate margins

Answer 15

These occur where two plates diverge (move apart), and new crust is created. In the oceans this produces mid-ocean ridges. Shallow focused earthquakes and submarine (underwater) earthquakes can occur at these margins. Divergence can also occur within a continent, resulting in rift valleys and volcanic activity.

Question 16

Continental crust

Answer 16

Forms the continents. Is thicker and older, on average 35km thick. Composed of granite. Formed at subduction zones

Question 17

Continental Drift

Answer 17

The movement of tectonic plates, due to varying weights of crust. It was originally thought that convection currents caused the movement of the plates, but now slab pull is thought of as the primary driving force.

Question 18

Controlled Burning

Answer 18

Intentionally burning vegetation with the aim of reducing fuel available for a wildfire and disrupting the fire’s path.

Question 19

Convection Currents

Answer 19

The circulation of magma within the mantle (asthenosphere). Magma is heated by radioactive processes in the core and cools at the surface, and so circulates between the two places

Question 20

Core

Answer 20

The densest, hottest part of the planet. Made of rocks rich in iron and nickel. Temperatures can exceed 5000oC. The heat is the result of primordial heat and radiogenic heat.

Question 21

Coriolis Effect

Answer 21

The Earth’s rotation causes objects not connected to the ground to deflect, including currents of air. The effect is responsible for the spin of tropical storms and is at its strongest either side of the equator at around 5o north and south.

Question 22

Crown Fires

Answer 22

Wildfires that burn the entirety of a tree (from top to bottom), often the most destructive and dangerous type of wildfire.

Question 23

Crust

Answer 23

Thinnest outer solid layer. Two types of crust, oceanic and continental.

Question 24

Cultural determinism

Answer 24

The view that cultural factors are significant in determining an individual’s or community’s capacity to cope with the impacts of a hazard. Cultural factors include a person’s values, beliefs and possibly their age and family situation.

Question 25

Deep-sea trenches

Answer 25

Found along the seaward edge of destructive margins. They are long, narrow, steep-sided depressions in the ocean floor. They mark where one plate begins to subduct beneath another.

Question 26

Degg's Model

Answer 26

This model shows that a hazard becomes a disaster if it affects a vulnerable population.

Question 27

Earthquakes

Answer 27

Tremors that result from the release of pressure that builds up in the Earth's crust due to plate movement.

Question 28

Economic determinism

Answer 28

The view that the wealth of an individual or community is the most significant factor in determining it's capacity to cope with and withstand the impact of a hazard.

Question 29

El Niño

Answer 29

A climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean. It can lead to drought conditions in SE Asia and eastern Australia, which increases the risk of wildfires.

Question 30

Epicentre

Answer 30

The point on the surface directly above the focus. Ground shaking is most intense here.

Question 31

Fatalism

Answer 31

An acceptance that hazards are a natural part of living in an area and that losses are inevitable. May be linked to a belief that they are 'God's will'.

Question 32

Faults

Answer 32

When rocks of the Earth's crust come under stress, they can fracture along cracks called faults. Plate movement creates such stress.

Question 33

Fire Breaks

Answer 33

The felling of trees and clearing vegetation to create a gap to disrupt a wildfire’s path.

Question 34

Focus

Answer 34

Also known as hypocentre. The breaking point of an earthquake, within the Earth's crust. Shallow focus earthquakes (0-70km) have a higher impact than deep focus earthquakes (300-700km)

Question 35

Geophysical hazards

Answer 35

Driven by the earth's own internal energy sources e.g., plate tectonics, volcanoes, seismic activity (earthquakes).

Question 36

Ground Fire

Answer 36

A slow smouldering fire that burns organic matter in the soil, such peat. They spread slowly at fairly low temperatures for long periods of time. There may be no flame.

Question 37

Hazard Distribution

Answer 37

The spatial coverage of a hazard. The area affected by a specific hazard. Some events are localised, and some have a much wider effect.

Question 38

Hazard Frequency

Answer 38

The distribution of a hazard through time. Some are very infrequent, and some are more regular.

Question 39

Hazard Magnitude

Answer 39

The size of impact of a hazard. This can be given using a scale for example the Richter scale for earthquakes, the Saffir-Simpson scale for tropical storms and the Volcanic Explosivity Index (VEI) for volcanic eruptions.

Question 40

Hazard perception

Answer 40

The way in which people receive and process information about a potential hazard and make sense of it. How people respond to a hazard links to their perception of the risk. Perception is influenced by a range of factors including socio-economic status, education, religion and cultural background.

Question 41

Hazard risk

Answer 41

The probability/chances of a hazard event occurring and creating loss of lives and livelihoods.

Question 42

Hazard vulnerability

Answer 42

The ability/inability to resist a hazard and respond when a disaster has occurred. Can be described as insecurity.

Question 43

Hot Spot

Answer 43

Volcanoes found away from the plate boundary, due to a magma plume closer to the surface.

Question 44

Hydrological hazards

Answer 44

Driven by water bodies, mainly oceans, e.g., floods, storm surges, tsunamis.

Question 45

Intertropical Convergence Zone (ITCZ)

Answer 45

The region near the equator where trade winds from the northern and southern hemispheres come together. The intense sun warms the surface at the equator causing the air to heat and rise, creating an area of low pressure and high precipitation.

Question 46

Intraplate

Answer 46

In the middle of a tectonic plate

Question 47

Island Arcs

Answer 47

A slightly curving line of volcanic islands formed at a subduction destructive margin off the coast of a continental plate or in the ocean where two oceanic plates converge.

Question 48

Island Chains

Answer 48

A line of volcanic islands that form in the middle of an ocean plate from lava erupted when the plate moves over a mantle plume.

Question 49

Jokulhaup

Answer 49

A sudden glacial flood caused by a glacier on top of or near a volcano melting due to the heat from the eruption.

Question 50

Ladder effect

Answer 50

When fires spread from the ground to the tree canopy

Question 51

Lahar

Answer 51

Destructive mudflows formed when ash and other volcanic material are mixed with water. They flow at speeds of up to 60km/h and are highly erosive.

Question 52

Landslide

Answer 52

A type of mass movement involving the rapid movement of soil and boulders down a slope. A secondary earthquake hazard.

Question 53

Lava

Answer 53

Once magma is ejected at the surface it is called lava.

Question 54

Lava flow

Answer 54

Molten rock flowing over the surface

Question 55

Liquefaction

Answer 55

When saturated unconsolidated sediments/soils are shaken by shockwaves their strength can fail causing them to behave more like a liquid. This secondary hazard can result in objects and buildings sinking into the sediments/soils.

Question 56

Lithosphere

Answer 56

The upper crust of the Earth (average thickness = 100km).

Question 57

Love (L) Waves

Answer 57

Surface waves that travel out from the epicentre and shake the ground from side to side. They are the slowest waves but are the most destructive which can cause significant damage to buildings and infrastructure.

Question 58

Magma Plumes

Answer 58

A huge upwelling of super-heated magma in the mantle that rises from a 'hot spot' and melts/pushes through the crust above causing lava to erupt at the surface.

Question 59

Management

Answer 59

Modern management techniques involve gathering accurate information, careful analysis and deliberate planning to make the most efficient use of the money and resources available.

Question 60

Mantle

Answer 60

Surrounds the core. The thickest layer made of silica rocks rich in iron and magnesium. The upper part of the mantle is semi-molten (plastic) and is known as the aesthenosphere. Convection currents occur here.

Question 61

Mercalli Scale

Answer 61

Measures the intensity of an earthquake event and its impact, rather than its magnitude. It is a 12-point scale.

Question 62

Mid-Ocean Ridge

Answer 62

Parting oceanic plates at a constructive plate boundary creates a ridge, with new land at the base of the oceanic valley.

Question 63

Mitigation

Answer 63

Actions aimed at reducing the seriousness of an event and lessening its impacts.

Question 64

Moment Magnitude Scale

Answer 64

An adaption of the Richter Scale that uses complex mathematics to calculate the total amount of energy released in an earthquake. Its values also range from 1-10 and it is more reliable than the Richter scale when measuring the largest earthquakes

Question 65

Natural disaster

Answer 65

A natural hazard becomes a disaster if there is a significant impact on people and property. According to the UN, this is when 10 or more people are affected, 100 or more people are affected, or the government declares a state of emergency.

Question 66

Natural hazard

Answer 66

An event caused by natural processes that is a threat to people and property.

Question 67

Nuées Ardentes

Answer 67

A type of pyroclastic flow that contains more dense material and so doesn't travel as far.

Question 68

Ocean ridges

Answer 68

The longest continuous uplift features on the surface of the planet. Where two plates pull apart there is a weaker zone in the crust and an increase in heat near the surface. The hotter expanded crust forms a ridge. The central part of the ridge may feature a central valley where a section of the crust has subsided into the magma below.

Question 69

Oceanic Crust

Answer 69

Crust, usually thinner than continental crust, that forms the sea floor. It is on average 7km thick.

Question 70

Paleomagnetism

Answer 70

The alternating polarisation of new land created. As magma cools, the magnetic elements within will align with the Earth’s magnetic field, which can alternate over thousands of years.

Question 71

Park’s Model

Answer 71

A model describing the decline and recovery of a country over time, following a natural disaster.

Question 72

Partial Melting

Answer 72

Elements within the lithosphere have different melting points, and so rock is partially melted, partially solid.

Question 73

Plate tectonic theory

Answer 73

This theory has evolved over many years. It suggests that the crust is divided into tectonic plates that move due to convection currents in the asthenosphere. This movement creates distinctive features including mid-ocean ridges, ocean trenches and fold mountains, in addition to causing earthquakes and volcanic activity

Question 74

Prediction

Answer 74

Improvements in technology, such as remote sensing and satellite images, have increased our ability to give advanced warnings of hazardous events. This allows for communities to take action.

Question 75

Primary (P) waves

Answer 75

Body waves that travel from the focus through both liquids and solids and are the fastest waves. They are compressional waves, which means that they compress and expand any material they move through.

Question 76

Primary impacts

Answer 76

Have an immediate effect on the affected area and are a direct result of the event.

Question 77

Primordial heat

Answer 77

Heat left over from the Earth's formation.

Question 78

Pyroclastic Flow

Answer 78

A mixture of hot rock, ash and gases rising from a volcanic eruption that moves at a rapid speed (up to 200m/s) along the ground. Temperatures range from 350-1000oC.

Question 79

Radiogenic heat

Answer 79

Heat produced by the radioactive decay of isotopes.

Question 80

Rayleigh (R) Waves

Answer 80

Surface waves that move in a rolling motion and can break up the surface.

Question 81

Ridge push

Answer 81

Also known as gravitational sliding. This occurs at mid-oceanic ridges where hot magma rises to the surface and the forces up the crust at constructive margin to form a slope on either side. As the new rock cools, it becomes denser and the weight causes it to 'slide' downwards away from the ridge, due to gravity. This results in a pushing force and in seafloor spreading.

Question 82

Rift valleys

Answer 82

At constructive margins in continental areas, such as East Africa, the brittle crust fractures as sections of it move apart. Areas of crust drop down between parallel faults to form rift valleys.

Question 83

Saffir-Simpson Scale

Answer 83

A 5-point scale that measure the magnitude of a tropical storm. The scale is based on measurements of central pressure, wind speed, storm surge and damage potential.

Question 84

San Andreas Fault

Answer 84

A visible line in the Earth's crust in California that marks an active conservative plate margin. Earthquakes occur here.

Question 85

Sea floor spreading

Answer 85

Surveys of the ocean floor established that rocks found closest to mid-oceanic ridges were the youngest and rocks nearest the continental landmasses were the oldest. This supported the idea that the sea floors were spreading out from the mid-oceanic ridges where new crust was being formed as magma reached the surface as two oceanic plate moved apart at a constructive margin.

Question 86

Secondary (S) Waves

Answer 86

Body waves that travel through the Earth but cannot travel through solids like the core. They are half as fast as Primary waves and are transverse waves, which means that they shake the ground at right angles to the direction of the wave

Question 87

Secondary Impacts

Answer 87

Happen after the disaster has occurred or are a knock-on effect of the disaster.

Question 88

Seismic

Answer 88

Relating to earthquakes or other vibrations of the Earth and it's crust.

Question 89

Seismic Waves

Answer 89

The energy released during an earthquake, in the form of Primary, Secondary, Love and Rayleigh Waves.

Question 90

Seisometer

Answer 90

A device that measures tremors in the Earth's crust. These occur when rising magma cracks and fractures overlying rocks.

Question 91

Slab pull

Answer 91

At a subduction plate margin, the heavier plate, usually basalt, sinks down into the mantle. As the edge of the plate sinks it pulls the rest of the plate with it.

Question 92

Storm 'eye'

Answer 92

Central point of a storm, 10-15km in diameter, where air sinks giving calm conditions and clear skies.

Question 93

Storm Surge

Answer 93

A rise in sea level that occurs during low pressure storms. The low pressure 'sucks up' the surface of the water and the storms produce strong winds that pile water against the shore, which can lead to flooding.

Question 94

Subduction

Answer 94

Oceanic plate is forced below continental plate, due to the oceanic plate being more dense than the continental plate.

Question 95

Surface Fire

Answer 95

The burning of leaf litter and low-lying vegetation. The most common type of fire. Can be low or high intensity. They cool quickly and are relatively easy to control.

Question 96

Surface Fires

Answer 96

Wildfires that only burn the leaf litter, and so are the easiest kind to extinguish.

Question 97

Surface waves

Answer 97

Travel along the Earth's surface and arrive after body waves.

Question 98

Tephra

Answer 98

Rock fragments ejected as part of an explosive volcanic eruption. They can vary in size from fine ash to larger 'volcanic bombs

Question 99

The Hazard Management Cycle

Answer 99

This represents hazard response as a continuous process. The cycle has 4 stages: Mitigation, Preparation, Response and Recovery.

Question 100

The Park Model

Answer 100

Also known as the disaster-response curve. It show's how people's quality of life is likely to change through the five phases of a disaster.

Question 101

The Richter Scale

Answer 101

A logarithmic 10-point scale used to measure the magnitude of earthquakes. Earthquakes above scale 6 are considered destructive.

Question 102

Tiltmeter

Answer 102

A device that measures changes in the angle of the slope of a volcano's sides. The sides of a volcano deform and bulge out as it fills with magma.

Question 103

Transform faults

Answer 103

Cracks in the Earth's crust that form at right angles to constructive plate margins. As the plates pull apart the parts of the crust on either side of the fault move at different rates, leading to friction and, ultimately, earthquakes.

Question 104

Tropical Storms

Answer 104

Intense low-pressure systems that develop in the tropics. These violent revolving storms usually measure some 200-700km in diameter. Known as hurricanes, cyclones and typhoons.

Question 105

Tsunamis

Answer 105

Giant sea waves generated by shallow-focus underwater earthquakes involving movements of the seabed e.g., when subduction occurs offshore. Secondary earthquake hazards. They travel at speeds of over 700km/h

Question 106

Volcanic Explosivity Index (V.E.I.)

Answer 106

A logarithmic scale from 0-8 which measures the magnitude of a volcanic eruption. The scale uses several volcanic characteristics to judge the size of an eruption, including eruption cloud height and volume of material erupted.

Question 107

Volcanic Island Arc

Answer 107

A series of volcanoes (often in the shape of an arc) that are formed consecutively, as a tectonic plate moves across a magma plume.

Question 108

Volcanoes

Answer 108

Openings in the Earth's crust through which lava, ash and gases erupt. They mark the presence of magma within the Earth's crust.

Question 109

Vulcanicity

Answer 109

All volcanic activities related to magma being forced into the Earth's crust.

Question 110

Wadati-Benioff Zone

Answer 110

A region of the subducting plate, most affected by pressure and friction, where most destructive margin earthquakes originate.

Question 111

Wildfire

Answer 111

An uncontrolled rural fire, known as bushfires in Australia and North America.

Question 112

Young fold mountains

Answer 112

Fold mountains are formed at destructive plate margins, either subduction or collision. Young fold mountains are 10 to 25 million years old and include the Rockies, Andes and Himalayas. They form from sedimentary rocks which crumple and fold as plates push together, causing uplift.