Tectonic Processes & Hazards - EQ1 - 1.2 Flashcards
How has the Earth’s structure has been established
- By studying the movement of seismic waves through the planet
- Seismic waves travel at different speeds through material of different densities, and some types (for example, S waves) do not travel through liquids
What is the thickness of the Earth’s crust and what does it form
- This is the thinnest layer and forms the outer shell on which life exists
- It varies in thickness from just 1km in some places to more than 80 kilometres in others.
What temperature is the earth’s crust
400°C at base
What is the density of the earth’s crust
less dense
What is the earth’s crust made up of
Granite/basalt
What state of matter is the earth’s crust
solid
Decribe the 2 types of crust’s depth, rock type & density - continental
- a thicker (45-50km), less dense layer (mostly granite)
Decribe the 2 types of crust’s depth, rock type & density - oceanic
- a thinner (6-10km), denser layer (mostly basalt)
The crust consists of……&…….&….tectonic plates
7 majorandseveral minor and dozens of small microplates
The……………….. …………….- is the boundary between the crust and the mantle is also known asMoho
Mohorovičićdiscontinuity
What is the Mohorovičićdiscontinuity
the boundary between the crust and the mantle is also known asMoho
The mantle is the …………. layer, being approximately ………. km thick.
The mantle is the thickest layer, being approximately 2,800 km thick.
What is the density of the mantle
- Mixed density layers (less to medium);
- Its density is 3.4g/cm3 at the top
- & 5.6g/cm3 at the bottom where it changes into the outer core
what are the states of matter in the mantle
- It is a solid layer but acts like a viscous liquid due to temperatures being close to the melting point of key minerals in this layer
- The lowermantle is ……. and …….. than the upper mantle
- The intense …….., at depth, keeps the lower mantle …..
- Thelowermantle is hotter and denser than the upper mantle
- The intense pressure, at depth, keeps the lower mantle solid
What is the types of rock in the mantle
- All of this mantle rock is comprised of a variety of oxides
- An example is peridotite
- Their atomic elements include oxygen, silicon and magnesium
The upper mantle has … layers
two
What are the 2 layers of the upper mantle
- The rigid layer above the asthenosphere, which together with the crust, makes up thelithosphere
- Theasthenosphereis a semi-molten, plastic type layer, which moves under high pressure
At the centre of the earth lies the …………
This is split into two sections: ……………….
At the centre of the earth lies the core This is split into two sections: theinner and outer core
State of matter & rock type of the inner core
Theinner coreis solid and is composed of iron and nickel
State of matter & rock type of the outer core
Theouter coreis composed of liquid iron (88%) and nickel
How thick is the inner core
1,221 km
How thick is the outercore core
2,259km
What is the density of the inner core
very dense - 12.8g/cm3 at the top of the section and 13.1g/cm3 at its deepest point