L2 - Tectonic Hazards

Question 1

How are earthquake magnitudes measured?

Answer 1

On a Richter scale up to 10. It is logarithmic, each number is 10 times worse than the previous.

Question 2

What are the features of earthquakes?

Answer 2

Hard to predict, start without warning and are catastrophic

Plates move past one another, don’t slide smoothly and get stuck building up pressure.

Question 3

What has pressure got to do with earthquakes?

Answer 3

Build up of pressure as plates get stuck releases energy along a fault
Energy travels in all directions as earthquake waves

Question 4

How are tsunamis formed?

Answer 4

When an earthquake, volcano or landslide happens on the ocean floor, water is displaced.
The water travels inland
900km/h
Powerful floods going km’s inland
Height less than 1m in ocean, up to 30m on land as water builds up

Question 5

What are the 2 types of volcanoes and at which boundaries are they formed?

Answer 5

Shield - found at hotspots and divergent plate boundaries

Composite - convergent plate boundaries

Question 6

What are the features of composite volcanoes?

Answer 6

Made at convergent/destructive plate boundaries
Acidic magma
Violent eruptions
Layers of ash and lava that have cooled as the viscous pyroclastic flows occur
Steep gradient

Question 7

What are the features of shield volcanoes?

Answer 7

Made at constructive/divergent plate boundaries
Gentle slopes
Fluid low viscosity lava
Gentle eruptions
Not much pyroclastic material released (gas and ash flow)