end of term test. bruh another one Flashcards
what is a natural hazard?
a natural event that poses risks to humans and property.
whats the difference between a natural hazard and a natural event?
a natural event doesn’t effect anybody or anything whereas a natural hazard poses a threat to humans.
when does a natural hazard become a disaster?
when it becomes a potential risk to humans
what are the 4 types of natural hazards?
tectonic, atmospheric, geomorphological and biological
what are tectonic hazards?
hazards associated with the movement of the tectonic plates
what are atmospheric hazards?
hazards associated with weather and climate events
what are geomorphological hazards?
hazards associated with the processes occuring on the earths surface
what are biological hazards?
hazards associated with the living world
what is the fatalistic approach?
if it happens it happens, its all part of living in this area
what is the acceptance approach?
we know hazards happen but we continue to live in this area because it has many advantages
what is the adaption approach?
events can be prevented and warnings given. the area is made safer with modern technology so even if a disaster occurs few people will be affected.
inner core:
this is solid and is the densest part of the planet and is composed of iron and nickel with a temperature of over 5500ºC
outer core:
its liquid and 1228km in diameter
mantle:
the mantle surrounds the core.its the thickest layer mainly composed of iron and magnesium. the rocks flow slowly as covection currents
crust:
the thinnest and outermost layer and has the coolest, least dense rocks.
what are the 2 types of crusts?
oceanic and continental
what is oceanic crust?
its composed mainly of relatively dense basalt rock and is around 6-10km thick
what is continental crust?
its composed of less dense igneous rock, metamorphic and sedimentary rock and can be up to 70km thick beneath major mountain ranges.
what was alfred wegners theory?
that all the continents were once joined together. he named this supercontinent, pangea.
how does a conservative plate margin move?
(passive-North American and Pacific Plates) Plates slide past each other in opposite directions, or in the same direction but at different speeds. this is responsible for earthquakes e.g. San Andreas fault, USA.
how does a destructive plate margin move?
(compressional-Nazca and South American plates) Here two plates are moving together (slab pull). When the denser plate subducts, friction causes it to melt and become molten magma. the magma forces its way up to the surface to form a volcano e.g. Cotopaxi. This margin is also responsible for devastating earthquakes, explosive eruptions, fold mountain ranges e.g. Andes and ocean trenches e.g. peru - chile.
how does a constructive plate margin move?
(tensional - North Amercian and Eurasian plates) Here 2 plates are moving apart (slab push) causing new magma to reach the surface through the gap. volcanoes formed along this crack cause a submarine mountain range such as those in the Mid Atlantic Ridge.
how to tectonic plates move?
these plates move due to convection currents in the mantle and where they meet tectonic activities occur.
what is the focus?
the point underground at which pressure release takes place
