The Earth's structure is responsible for tectonic hazards Flashcards
What is the core?
Made up of dense rock containing iron and nickel alloys and is divided into a solid inner core and a molten outer one
How hot is the core?
Over 5000 degrees
How is the heat produced in the core?
Primordial heat left over from the earth’s formation
Radiogenic heat produced by the radioactive decay of isotopes
What is the mantle?
Made up of molten and semi-molten rocks containing lighter elements such a silicon and oxygen
What is the crust?
Even lighter than the mantle
Made of silicon, oxygen, aluminium, potassium and sodium
How thick is the crust under the ocean?
6-10km thick
How thick is the crust under the continents?
30-40km thick
How thick is the crust under the highest mountain ranges?
70km thick
What has new research suggested about the upper mantle and the crust?
It should be divided into the lithosphere and asthenosphere
What is the lithosphere?
Consists of the crust and the rigid upper section of the mantle
How thick is the lithosphere?
80-90km thick
Why is the lithosphere important?
It is divided into seven very large plates and a number of smaller ones
What are the seven plates in the lithosphere divided into?
Two categories - oceanic and continental
What is the asthenosphere?
Lies beneath the lithosphere and it semi-molten on which the plates float and move
What theory did Alfred Wegener publish in 1912?
The theory that a single continent existed about 300 million years ago called Pangea