Hazardous Earth Flashcards
what is at the very centre of the earth
core
what are the properties of the core
the core’s inner section is solid and the outer is liquid
the core is dense at the centre but less dense further away
the temperature inside ranges from 4400-6000
what is around the core
the mantle
what are the properties of the mantle
the mantle is made up of silicon based rocks
part nearest to the core is rigid
layer after is the asthenosphere which is semi-molten
temperature ranges between 1000-3700`
what is the outer layer of the earth called
the crust
what is the crust made up of
made up of silicon based rocks
what are the two types of crust
oceanic and continental
which crust is thinner and denser
oceanic
what is the word for the slabs the crust is divided into
tectonic plates
what is the process of convection currents
in the earth’s core and mantle, radioactive decay produces heat. The heat is transmitted to the second layer of the mantle. The layer gets hotter and rises upwards towards the crust because it has become less dense. The magma gets cooler as it is further way from the core. It becomes denser and sinks. These circular movements of hot and cold rocks is called convection currents.
why do convection currents cause earthquakes
because it causes the tectonic plates to move apart or towards each other due to friction
what are plate boundaries
where tectonic plates meet
what are the three type of plate boundaries
conservative
divergent
convergent
how do convergent plate boundaries cause earthquakes
two plates move towards each other
the oceanic plate slides beneath the continental plate. The rocks catch against one another. Pressure between the plates build until they cannot take energy. The two plates slip past each other, which cause both plates to move causing an earthquake
how do conservative plate boundaries cause earthquakes
at the conservative plate boundaries plates move past each other in the opposite or same direction at different speeds. The plates are made of sharp pointed edges so they snag against one another. Pressure builds up until the plates cannot take it anymore. They slip past each other resulting into an earthquake
how do divergent plate boundaries form a volcano
plates move apart. The convection currents diverge and cause a gap between the plates. Magma rises up to fill the gap
where are volcanoes found
at convergent and divergent plate boundaries
how does a volcano form at convergent plate boundaries
the oceanic plate moves beneath the mantle where it is destroyed
magma forms
the magma rises through the cracks of the crust
the magma erupts onto the surface forming a volcano
where do hotspots form
where a plume of hot magma from the mantle moves towards the surface, causing large flow of heat from the mantle to the crust
how do hotspots form volcanoes
the magma breaks through the crust and reaches the surface causing an eruption forming a volcano
what are the two different type of volcanoes
composite and shield
where do composite volcanoes form
at convergent plate boundaries
what are the properties of composite volcanoes
have explosive eruptions and deposit a layer of ash at the start due to ashy explosions
they erupt andesitic lava that has high silica content making the lava thick and sticky
lava cannot flow far so it forms a steep-sided cone
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