natural hazards Flashcards
what is a natural hazard
an sudden natural event that can have a huge negative impact on social and environmental factors
what is a hazard risk
the chance of being affected by a natural hazard
why do people live in places of hazard risk
-no knowledge of disasters
-rich agricultural land
-too poor to move
-family and cultural ties
how does urbanisation increase the risk of exposure to natural hazards
-densely populated urban areas concentrate those at risk
how does poverty increase the risk of exposure to natural hazards
poor built homes can collapse easily
how does farming increase the risk of exposure to natural hazards
the attraction of fertile silt on floodplains puts people at risk
how does climate change increase the risk of exposure to natural hazards
global warming raises sea levels and generates more extreme weather
what does spreading convection currents cause
the rising of magma at constructive margins
what doe sinking convection currents cause
the subduction of a plate beneath the other at a destructive plate boundary
what happens at a constructive margin
plates separate
what happens at a destructive margin
plates collide
what happens at a conservative margin
plates slide past each other
what is an earthquake
a sudden, violent period of the ground shaking
where and how is an earthquake caused
-they mostly occur at the margin of slow moving tectonic plates,
-friction and sticking between plates cause enormous stresses and pressure which build to a breaking point
what is the global distribution of earthquakes
-in linear belts that correspond with plate margins
-sparsely distributed earthquakes correspond with constructive plate boundaries
-pacific ring of fire- destructive plate boundaries
where do most volcanoes occur
along plate margins “pacific ring of fire”
what happens at a constructive plate margin
-two plates move apart and magma forces its way to the surface, as it breaks the crust an earthquake occurs
-magma released results in a broad and flat shield volcano
what happens a conservative margin
-two plates move past each other at different rates, friction triggers earthquakes
-no volcanoes because no magma
what happens at a destructive plate boundary
-where two plates one towards each other and the dense oceanic plate subjects
-friction causes earthquakes
-sinking oceanic plate Cretes gas-rich magma resulting in a volcano
what happens at a destructive margin when there are two continental plates
-there is no subduction
-so there is no magma for a volcano
-the crust crumples and lifts to form fold mountains
-earthquake’s can be triggered
