Earthquakes

• Aims

• To know where earthquakes occur

• To know how earthquakes occur

• To be able to give examples of

earthquakes

• To know about the characteristics of

earthquakes in different parts of the world

Fault

• a fracture in the rocks of the Earth’s crust,

where compressional or tensional forces

cause relative movement of the rocks on

the opposite sides of the fracture.

• Can be a few centimetres to many

hundreds of kilometres long

Describe the distribution of earthquakes

Map of plate boundaries

• https://www.youtube.com/watch?v=e7ho6

z32yyo

Earthquake depth

• Earthquakes can occur anywhere between

the Earth's surface and about 700

kilometers below the surface.

• Shallow earthquakes are between 0 and

70 km deep; intermediate earthquakes, 70

- 300 km deep; and deep earthquakes,

300 - 700 km deep.

• Deep focus earthquakes tend to be along

island arcs and subduction zones (around

the Benioff zone) Why is this odd?????

How do earthquakes occur?

Plates become stuck and stop moving

Pressure builds up underneath the

crust

Eventually the pressure becomes too

much and the plates move with a jolt

This is an earthquake

Exceptions

• Mines

• Reservoirs

• Old fault lines e.g. Market Raesen 2008

5.2 on the Richter Scale

How do earthquakes occur?

1. General

explanation

Collision

DestructiveConstructive

Conservative Other

Seismicity

Explain how earthquakes

occur on each plate

margin. Add in examples

with dates and Richter

Scale Readings.

P and S waves •P waves travel through solids and liquids

•They travel very fast (nearly twice the speed of

S waves – 300m/s through air, 5000m/s through

granite

•They push and pull and can compress

•S waves can travel through solids but not

liquids.

•They vibrate from side to side

•They travel more slowly than P waves – about

60% slower

•The side to side movement causes the most

damage to buildings as a result of the shearing

effect.

•The lack of S waves and the slowness of P

waves was used to discover that the outer core

is liquid

https://www.youtube.com/w

atch?v=gFU3_mZdGfY

Discuss why surface

waves (Love and

Rayleigh) are the most

damaging.

Earthquakes

• Aims

• To know where earthquakes occur

• To know how earthquakes occur

• To be able to give examples of

earthquakes

• To know about the characteristics of

earthquakes in different parts of the world