hazards key terms Flashcards
what is a geophysical hazard?
potentially damaging natural event which may cause the loss of life or injury, property damage, social and economic disruption, or environmental degradation
what is a atmospheric hazard?
potentially damaging natural event associated with changes in atmospheric hazards
what is a hydrological hazard?
extreme events associated with water occurrence, movement and distribution
what is hazard perception?
the way in which an individual or a group view the threat of a hazard event and this ten influences their actions
what is fatalism?
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
what is prediction?
the ability to give warnings so that action can be taken to reduce impacts - improved by monitoring, information sharing and communication technologies
what is adjustment/ adaptation?
attempts by individuals and communities to live with hazard events and reduce their level of vulnerability
what is mitigation?
actions taken to help reduce or eliminate long-term risks caused by hazards
what is resilience?
the sustained ability to respond to, withstand and recover from the effects of natural hazards
what is risk sharing/ preparedness?
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
what is hazard frequency?
how often a hazard occurs- generally smaller hazard occurs more frequently and larger hazards occur less frequently
what is hazard intensity?
the measurement of the impacts of the hazard on a place (e.g Mercalli scale)
what is magnitude?
an assessment of the size of an event (the amount of energy released)
what is hazard distribution?
the pattern of where each hazard types most likely to occur (and areas which don’t experience these)
what is lack of development?
is related to increase in economic output (wealth) coupled with improvement in social and political welfare of people within a country
what is the parks model?
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
what is the hazard management cycle?
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
what is the plate tectonic theory?
the theory that Earths outer layer is divided into several plates that move over the mantle; the rocky inner layer above the core
what is crustal evolution?
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
what are tectonic plates?
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
what is gravitational sliding?
the movement downward or downslope of rock/ lava in response to gravitational instability along particular slopes in unstable regions such as mid-oceanic ridges
what is ridge push?
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
what is slab pull?
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
what are convection currents?
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
what is sea-floor spreading?
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
what is a constructive plate margin?
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
what is a destructive plate margin?
sometimes called a convergent or tensional plate margin and this occurs when oceanic and continental plates move together leading to folding or subduction
what is a constructive plate margin?
sometimes called transform faults and these occur when plates slide past each other in opposite directions, but without creating or destroying lithosphere
what are young fold mountains?
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
what are rift valleys?
a steep-sided valley formed by the downward displacement of a block of the earth’s surface between the parallel faults or faults systems
what are ocean ridges?
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
what are deep sea trenches/ oceanic trench?
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
what are island arcs?
volcanic islands that form parallel to ocean trenches in subduction zones
what are magma plumes?
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
what are lava flows?
a mass of flowing or solidified lava on the Earth’s surface
what is pyroclastic flows (nuees ardente)?
a mixture of hot gas (over 800 degrees C) and tephra which can flow at high speed (over 700 km/ph) down volcanic slopes
what is tephra?
the solid matter ejected by a volcano into the air ranging in size from large volcanic bombs to fine ash
what is a lahar?
hot mudflows formed when volcanic ash mixes with water (usually heavy rain) and flows downhill at speed- volcanic mudflows
what is acid rain?
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
what does seismic mean?
relating to earthquakes or other vibrations of the Earth and its crust
what does liquefaction mean?
when soil with high water content loses its mechanical strength and starts to behave like a fluid once shaken by earthquake tremors
what is a tsunami?
a giant sea wave generated by shallow focus underwater earthquakes, volcanic eruptions and large landslides into the sea
what is a landslide?
slope failure as a result of the land shaking in an earthquake leading to the mass movement of land downward
what are shockwaves/ seismic waves?
energy waves produced by an earthquake which spread in all directions through different geologies at different rates away from the focus
what are storm surges?
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
what is the Saffir-simpson scale?
the scale used to measure tropical storm magnitude
what is retrofitting?
adjusting older buildings with new designs, materials, devices and technologies to help them withstand hazards better
what is an ignition source?
a natural or human source of a wildfire being set alight e.g lightning or agricultural fires becoming out of control
what is phrophytic vegetation?
plants adapted to tolerate fire through methods such as thick bark, tissue with high moisture content, seeds set by fire and underground nutrition storage
what are retardents?
chemicals sprayed on wildfires in order to slow them down and made from nitrates, ammonia, phosphates , sulphates and thickening agents
what is a multi-hazardous environment?
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
