Hazardous environments Flashcards
what is a hazard
event which has potential to cause harm to environment, people or economy
magnitude
strength of an event
frequency
how often an event occurs
size
the area covered by hazard
duration
time a hazard event lasts
location
where a hazard event occurs
what are tropical cyclones
rotating, low pressure systems
characteristics of cyclones
- heavy rainfall
- high wind speeds
- high waves and storm surges
what is magnitude of cyclones measured by
Saffir- simpson scale
1-5
where do tropical cyclones develop
between 5 and 30 degrees south and north of equator
what is an earthquake
sudden, violent shaking of the ground
why do earthquakes occur
pressure building when tectonic plates move
epicentre
point on earths surface directly above focus
focus
point at which earthquakes starts below earths surface
how is magnitude of earthquakes measure
Richter scale or moment magnitude scale
damage of earthquakes measured by
Mercalli scale
what is a volcano
when magma erupts on earth surface as lava
where do volcanoes occur
at constructive and destructive plate boundaries
where are most active volcanoes located
ring of fire
what ae hotspots
plumes of magma escaping through earths crust
what is magntitude of volcanic euroption measured by
Volcanic explosivity index
causues of tropical cyclone hazards
- low pressure (less than 950mb)
- sea surface temp over 27
- between 5 and 20
- low wind shear
- deep layer of humid air
coriolis force
force created by rotation of earth
features of tropical cyclone
- heavy rainfall
- high wind speeds
- storm surges
- calm eye
- highest wind and rain at eye
- diameter upto 800km
types of plate boundaries
- constructive
- destructive
- collision
- conservative
constructive plate
plates move apart
what occurs at constructive plate
volcanic and earthquakes
destructive plate
- the plates move together
- denser plate subducts under less dense plate
what occurs at destrcutive plates
volcanic and earthquakes
collision boundary
two plates of similar move towards each other so land is pushed upwar
what does collision boundary form
fold mountains
consevative boundary
plates move past each other in opposite directions creating friction
what happens at conservative boundary
eathquakes
volcanoes at constructive boundaries
- occurs under the sea
- lava escapes through gap
- lava cools and hardens creating a new crust
type of volcanoes at constructive boundaries
- lava is runny and less explosive
- shield volcanoes
Volcanoes at Destructive Boundaries
- in subduction zone, it causes friction
- causes heat and plate material melts which forms magma
- magma rises to surface through cracks in crust
- cooling lava and ash build up forming a volcano
type of volcanoes at destructive boundaries
- sticky lava and explosive eruptions
- forms composite or stratovolcanoes
primary hazards of volcanoes
- pyroclastic flow
- lava flow
- gas emissions
- volcanic bombs
secondary hazards of volcanic eruption
- lahars
- acidification
- landslides
- climate change
- fire
- floods
at which plate are earthquakes weaker and why
constructive because plates are moving apart
primary hazards of earthquakes
- collapse of infrastructure
- landslides
- gas leaks
- fires
- soil liquifaction
- subsidence
- mud flows
- tsunamis
earthquake sequence
- pressure builds up
- plates jolt free and pressure is released as energy
- the point at which the earthquake starts is the focus
- energy passes through earth’s crust as waves
reaons why humans live in hazardous areas
- lack of education
- advantages of livng in the area outweighs disadvanatges
- too poor
- has connections to area
list 4 economic factors which affects vulnerbility to a hazard
- wealth and level of development
- insurance
- buildings
- technology
2 social factors which affect vunerability
population density
- education
2 physical factors which affect vulnerability
- global location
- physical environment
what helps predict earthquakes
- tiltmeters
- clusters of small earthquales
- radon gas emissions
- remote sensing of ground movement
what are ways countries can prepare for earthquakes
- building designs
- earthquake drills
- emergency planning
what are types of building designs for earthquakes
- shutters on windows
- deep foudnations
- rubber shock absorbers
what can remote sensing help with
changes in ground movement
what does GIS help with
- vulnerable areas
- land use
- infrastructure such as roads
short term responses to earthquakes
- searching collapsed buildings
- medical assistance
- distribuition of food and water
- people shelter
- clearing rubble
long term responses to earthquakes
- risk assessment
- hazard mapping
risk defenition
probability that a hazard will have harmful consequences
hazard mapping
- maps areas where earthquakes are more likely to occur
