hazards key terms

Question 1

what is a geophysical hazard?

Answer 1

potentially damaging natural event which may cause the loss of life or injury, property damage, social and economic disruption, or environmental degradation

Question 2

what is a atmospheric hazard?

Answer 2

potentially damaging natural event associated with changes in atmospheric hazards

Question 3

what is a hydrological hazard?

Answer 3

extreme events associated with water occurrence, movement and distribution

Question 4

what is hazard perception?

Answer 4

the way in which an individual or a group view the threat of a hazard event and this ten influences their actions

Question 5

what is fatalism?

Answer 5

a view that suggests people cannot influence outcomes therefore nothing can be done to reduce (mitigate) the event or its impacts: an act of God; people remain

Question 6

what is prediction?

Answer 6

the ability to give warnings so that action can be taken to reduce impacts - improved by monitoring, information sharing and communication technologies

Question 7

what is adjustment/ adaptation?

Answer 7

attempts by individuals and communities to live with hazard events and reduce their level of vulnerability

Question 8

what is mitigation?

Answer 8

actions taken to help reduce or eliminate long-term risks caused by hazards

Question 9

what is resilience?

Answer 9

the sustained ability to respond to, withstand and recover from the effects of natural hazards

Question 10

what is risk sharing/ preparedness?

Answer 10

prearranged measures to reduce the loss of life and property damage through education, evacuation procedures, provision of emergency shelters and the taking out of insurance

Question 11

what is hazard frequency?

Answer 11

how often a hazard occurs- generally smaller hazard occurs more frequently and larger hazards occur less frequently

Question 12

what is hazard intensity?

Answer 12

the measurement of the impacts of the hazard on a place (e.g Mercalli scale)

Question 13

what is magnitude?

Answer 13

an assessment of the size of an event (the amount of energy released)

Question 14

what is hazard distribution?

Answer 14

the pattern of where each hazard types most likely to occur (and areas which don’t experience these)

Question 15

what is lack of development?

Answer 15

is related to increase in economic output (wealth) coupled with improvement in social and political welfare of people within a country

Question 16

what is the parks model?

Answer 16

a model graph to show the effects of a hazard on quality of life over a sequence of time and expected stages from pre-event to eventual recovery

Question 17

what is the hazard management cycle?

Answer 17

the continuous process by which individuals and communities manage hazards in an effort to avoid or mitigate the impacts resulting from the hazards and learn to manage and prepare for them better over time

Question 18

what is the plate tectonic theory?

Answer 18

the theory that Earths outer layer is divided into several plates that move over the mantle; the rocky inner layer above the core

Question 19

what is crustal evolution?

Answer 19

the rate of continental crustal growth and recycling through time and how changes in tectonic movement have influenced the rates of crustal growth and preservation

Question 20

what are tectonic plates?

Answer 20

the large, separately moving areas of the lithosphere that are the result of its breaking apart into seven or eight major sections (depending on how they are defined) and many minor ones

Question 21

what is gravitational sliding?

Answer 21

the movement downward or downslope of rock/ lava in response to gravitational instability along particular slopes in unstable regions such as mid-oceanic ridges

Question 22

what is ridge push?

Answer 22

a proposed driving force for plate motion that occurs at mid-ocean ridges as the result of the rigid lithosphere sliding down the hot, raised asthenosphere underneath mid-ocean ridges- this push is caused by gravitational force and it exists because the ridge occurs at a higher elevation than the rest of the ocean floor

Question 23

what is slab pull?

Answer 23

the portion of motion of a tectonic plate that can be accounted for by its subduction and it is partly driven by the weight of cold, dense plates sinking into the mantle at oceanic trenches- the cooler sinking plate pulls the rest of the warmer plate along behind it

Question 24

what are convection currents?

Answer 24

heart from the earth’s core is transferred to the mantle. rock, close to the core, is heated as so has plasticity and so it rises. when it reaches the crust it is forced sideways as often it cannot pass through the crust. the frictional drag between the convection current and the lower surface of the crust causes the tectonic plate to move. the more liquid rock then sinks back towards the core as it cools, process then repeats

Question 25

what is sea-floor spreading?

Answer 25

the formation of fresh areas of oceanic crust which occurs through the upwelling of magma at mid-ocean ridges and its subsequent outward movement on either side

Question 26

what is a constructive plate margin?

Answer 26

sometimes called a divergent plate margin, occurs when plates move apart and magma wells up to fill the gap forming volcanic activity and new crust

Question 27

what is a destructive plate margin?

Answer 27

sometimes called a convergent or tensional plate margin and this occurs when oceanic and continental plates move together leading to folding or subduction

Question 28

what is a constructive plate margin?

Answer 28

sometimes called transform faults and these occur when plates slide past each other in opposite directions, but without creating or destroying lithosphere

Question 29

what are young fold mountains?

Answer 29

mountains that form mainly by the effects of folding on layers within the upper part of the earth's crust eg the Himalayas - at convergent margins

Question 30

what are rift valleys?

Answer 30

a steep-sided valley formed by the downward displacement of a block of the earth's surface between the parallel faults or faults systems

Question 31

what are ocean ridges?

Answer 31

an elevated region with a central valley on an ocean floor at the boundary between two diverging tectonic plates where new crust forms from upwelling magma

Question 32

what are deep sea trenches/ oceanic trench?

Answer 32

any long, narrow, steep-sided depression in the ocean bottom in which occur the maximum oceanic depths, approximately 7,300 to more than 11,000 metres (24,000 to 36,000 feet) and they typically form in subduction zones

Question 33

what are island arcs?

Answer 33

volcanic islands that form parallel to ocean trenches in subduction zones

Question 34

what are magma plumes?

Answer 34

upwelling of abnormally hot rock within the Earth's mantle which can partly melt when they reach shallow depths near the surface and so are thought to be the cause of volcanic centres and hotspots

Question 35

what are lava flows?

Answer 35

a mass of flowing or solidified lava on the Earth's surface

Question 36

what is pyroclastic flows (nuees ardente)?

Answer 36

a mixture of hot gas (over 800 degrees C) and tephra which can flow at high speed (over 700 km/ph) down volcanic slopes

Question 37

what is tephra?

Answer 37

the solid matter ejected by a volcano into the air ranging in size from large volcanic bombs to fine ash

Question 38

what is a lahar?

Answer 38

hot mudflows formed when volcanic ash mixes with water (usually heavy rain) and flows downhill at speed- volcanic mudflows

Question 39

what is acid rain?

Answer 39

rainfall made acidic by mixing with sulphur and nitrogen oxides which combine with atmospheric water (water vapour) to form acids- can be natural from volcanic activity or man-made from industrial smoke pollution

Question 40

what does seismic mean?

Answer 40

relating to earthquakes or other vibrations of the Earth and its crust

Question 41

what does liquefaction mean?

Answer 41

when soil with high water content loses its mechanical strength and starts to behave like a fluid once shaken by earthquake tremors

Question 42

what is a tsunami?

Answer 42

a giant sea wave generated by shallow focus underwater earthquakes, volcanic eruptions and large landslides into the sea

Question 43

what is a landslide?

Answer 43

slope failure as a result of the land shaking in an earthquake leading to the mass movement of land downward

Question 44

what are shockwaves/ seismic waves?

Answer 44

energy waves produced by an earthquake which spread in all directions through different geologies at different rates away from the focus

Question 45

what are storm surges?

Answer 45

very high local sea levels caused by the wind driving waves so that they pile up against a coast added to atmospheric low pressure heaving/ sucking the ocean surface higher

Question 46

what is the Saffir-simpson scale?

Answer 46

the scale used to measure tropical storm magnitude

Question 47

what is retrofitting?

Answer 47

adjusting older buildings with new designs, materials, devices and technologies to help them withstand hazards better

Question 48

what is an ignition source?

Answer 48

a natural or human source of a wildfire being set alight e.g lightning or agricultural fires becoming out of control

Question 49

what is phrophytic vegetation?

Answer 49

plants adapted to tolerate fire through methods such as thick bark, tissue with high moisture content, seeds set by fire and underground nutrition storage

Question 50

what are retardents?

Answer 50

chemicals sprayed on wildfires in order to slow them down and made from nitrates, ammonia, phosphates , sulphates and thickening agents

Question 51

what is a multi-hazardous environment?

Answer 51

a place with more than one hazard type happening over time- meaning there are interrelations between these hazards, including their simultaneous (at the same time) or cumulative (one after the other) occurrence and also their potential interactions e.g storms + vlocanic activity = lahar