plate tectonics Flashcards
(29 cards)
how thick is the crust and what is it made up of?
up to 70km think and is made up of giant sections called plate tectonics
how thick is the mantle and what consistency does it have
up to 2900km think and due to high temperature it has a jam consistency
how thick is the outer core and what is it
up to 2200km thick and it is the solid layer
how thick is the inner core and what is it
up to 1200km thick and it is a solid layer
what are the 4 sections of the earth called
the crust, the mantle, the inner core and the outer core
what happens in the mantle and what is the effect of it
convection currents which move the plates around the earths surface
why does the earth release huge amounts of heat energy
because of the extremely high temperatures
what happens in the upper and lower mantle
in the lower mantle the warmer fluid starts to rise and in the upper mantle the cooler liquid starts to sink
what are earthquakes and where do they occur
they are vibrations of the earths crust caused by movement at plate boundaries and major fault line. they mostly happen at plate boundaries and major fault lines
what is the focus and where is the epicentre
the focus is where during an earthquake seismic waves move out from the point where rocks of tectonic plates move. the epicentre is directly above the focus on the earths surface
what is the richter scale
it is used to measure the magnitude ( power ) of a tremor using an instrument called a seismograph
why do earthquakes happen so suddenly
because it is the two plates sliding together which makes the rock suddenly give way with no warning
what short term/immediate effects do earthquakes have
electricity cuts off debris causes injury/death roads are destroyed water or gas mains burst buildings collapse
what long term/knock on effects do earthquakes have
people loose livelihood landslides mental trauma tsunamis disease
how can you limit the damage on a building
identification number for helicopters rolling weights on roof to counter react shock waves automatic shutters on windows deep and firm building foundations rubber shock absorbs beneath buildings open are for pedestrians to assemble
what is a volcano
an opening or vent that allowed molten lava to erupt through it and solidify as igneous rock
what is the definition of an active, dormant and extinct volcano
an active one is able to erupt at anytime, a dormant one has not erupted for years and an extinct one has not erupted for a very long time and is unlikely to ever again
what is lava flow
lava flow is created by a non-explosive eruption. it consist of molten rock, is thick and can travel far without solidifying
what is ash
the smoke cloud seen from an eruption which can travel for miles and settles as ash fall
what is gas
volcanoes produce gas when erupting. including CO2, steam and sulphur dioxide which smells of rotten eggs
what is pyroclastic flow
floods of gas, lava and rock that rush down the volcano after an eruption
what is acid rain
the sulphur emissions from volcanoes that cause acid rain
what is lahar
a mudflow that comes from a volcano. it can be dangerous due to its energy and speed. it is fluid when moving until stopped which it then solidifies
what is the use of a spectrometer
it is used to measure the amount of sulphur dioxide gas that is being emitted by a volcano
