SECTION A Flashcards
what does natural hazard mean
natural hazards are sudden, severe events which make the natural environment difficult to manage
what factors affect risk
urbanisation
poverty
farming
climate change
what is an earthquake and where do they occur and how
a sudden, violent period of ground shaking. most occur at slow moving tectonic plates. friction and sticking between plates create enormous pressures and stresses which build to a breaking point
where do volcanoes occur
like earthquakes most volcanoes occur in belts along plate margins
what are the two types of crust state characteristics
OCEANIC - thin, dense
CONTENTIAL- thicker, less dense
what happens at constructive margins
plates separate
causing mild earthquakes and volcanic eruptions
plates do what at destructive margins
COLLIDE
causing strong earthquakes and violent volcanic eruptions
what happens at conservative margins
plates SLIDE
causing powerful earthquakes
why do people live at risk from tectonic hazards
uneducated volcanoes can bring benefits such as fertile soils poor people they are rare aseismic buildings reduce risk
what happens at a constructive plate margin
the two plates move apart and magma forces its way to the surface as it breaks the crust it causes mould earthquakes the magma is very hot and fluid allowing the lava to flow along way before cooling this results in typically broad and flat shield volcanoes e.g. mid-Atlantic ridge
what happens at a destructive plate margin
two plates move towards each other the dense Oceanic plate is subducted beneath the less dense continental plate which is a strong update the sinking oceanic plate create sticky gas rich magma this results in suicided composite volcano erupted violently where two continental plates meet there is no subduction zone so no magma to form volcano the crust crumples and lifts to form fold mountains powerful earthquakes can be triggered
what happens conservative margin
two plates move past each other a different rate of friction between the plates build stresses and trigger earthquakes when they slip there is no volcanoes because there is no magma
how can risks from tectonic hazards be reduced
monitoring
protection
planning
prediction
how do u monitor earthquakes
generally occur without warning. these events can include
•microquakes before the main tremor
•bulging of the ground
• raised groundwater levels
how do u monitor volcanoes
monitored using hi-tech scientific equipment:
•remote sensing
•seismicity
•ground deformation
planning in volcanoes and earthquakes
volcanoes
risk assessment and hazard mapping to identify areas to practise evacuation or restrict building
earthquakes
mapping is to identify areas to protect buildings and infrastructure
protection in volcanoes and earthquakes
VOLCANOES
little can be done to protect property but earth embankments used to divert lava flows
EARTHQUAKES
drills to help keep people alert and prepared but earthquake resistant construction is the best way to reduce risk
