Tectonic plates, volcanoes and earthquakes

Question 1

what are the 2 types of crust that plates are made of?

Answer 1

• continental crust is thicker and less dense
• oceanic crust is thinner and more dense

Question 2

why are the plates moving?

Answer 2

because of convection currents in the mantle

Question 3

what are the places where plates meet called?

Answer 3

plate margins/boundaries

Question 4

what are the three types of plate margin?

Answer 4

• destructive margins
• constructive margins
• conservative margins

Question 5

what are destructive margins? what happens?

Answer 5

• where two plates are moving towards each other
• where an oceanic plate meets a continental plate, the denser oceanic plate is subducted and destroyed, creating magma

Question 6

what are constructive margins? what happens?

Answer 6

• where two plates are moving away from each other
• magma rises from the mantle to fill the gap and cools, creating new crust

Question 7

what are conservative margins? what happens?

Answer 7

• where two plates are moving sideways past each other or moving in the same direction but at different speeds
• crust isn’t created or destroyed

Question 8

where do volcanoes occur?

Answer 8

at destructive and constructive plate margins?

Question 9

what happens at the destructive margin to create a volcano?

Answer 9

as one plate subducts under the other, the lower plate is forced downward and the rock melts into magma

Question 10

what happens at the constructive margin to create a volcano?

Answer 10

as the plates pull apart, molten rock (magma) rises up and erupts as lava, creating new ocean crust.

Question 11

where do earthquakes occur?

Answer 11

all plate margins (destructive, constructive and conservative)

Question 12

what happens at the destructive margin to create an earthquake?

Answer 12

tension builds when one plate gets stuck as it moves past each other

Question 13

what happens at the constructive margin to create an earthquake?

Answer 13

tension builds along cracks in the plates as they move away from each other

Question 14

what happens at the conservative margin to create an earthquake?

Answer 14

tension builds up when plates that are grinding past each other get stuck

Question 15

so how do the earthquakes vibrate the earth?

Answer 15

the plates eventually jerk past each other, sending out shock waves

Question 16

what is the moment magnitude scale?

Answer 16

measures the amount of energy released by an earthquake (magnitude)

Question 17

how do you know how dangerous the earthquake is from the moment magnitude scale?

Answer 17

magnitude 6 and below normally causes slight damage, although they can be worse in built up areas
magnitude 7 and above can cause major damage and deaths