Earthquakes

Question 1

What is an earthquake?

Answer 1

Movement within the Earth’s crust causes stress to build up

When the stress exceeds the strength of the rock the rock fractures

The stored energy is released as an earthquake

Intense seismic waves spread out from the focus

These waves are what causes the ground to shake

Shallow focus = more destruction

Question 2

What are P waves?

Answer 2

Primary Waves

Arrive at the detector first

Are longitudinal waves - The vibrations are in the same direction as the direction of travel

Can travel through solids and liquids

Can be detected on the other side of the Earth

Question 3

What are S waves?

Answer 3

Secondary Waves

Arrive at the detector second

Are transverse waves - The vibrations go at right angled to the direction of travel

Can only travel through solids

Can only be detected on the same side of the Earth as the earthquake

Question 4

How do we measure earthquakes?

Answer 4

Used to measure earthquakes.

Logarithmic Scale - Each point is 10 time stronger than the last.

For each point, approximately 30 times more energy is released.

Question 5

What are the primary effects of an earthquake?

Answer 5

Ground shaking

Ground rupture

Question 6

What are the secondary effects of an earthquake?

Answer 6

Soil Liquefaction

Tsunamis

Effects on People & the Built Environment

Landslides & Avalanches

Fires