1. Exactly what is it and how does it occur?
Liquefaction
Exactly what is it and how does it occur?

2. How Does It Occur
Watch
At the very beginning Carly mentions saturated sandy soil that is subjected to the ground’s shaking.
But what exactly does this mean?

3. Prerequisites: So we need soil that is..
1. Saturated
2. Sandy
When something cannot absorb any more moisture;
when clouds become saturated for example, they rain
Loose sandy soil allows water to squeeze between the grains when it is shaken up

4. And you get that soil liquefying
Now add
A shallow earthquake, like our 5km Feb 22nd Quake
And you get that soil liquefying
Soil that turns into liquid, causing everything that is on top of it to sink. Such as houses in Baxley Park (East Christchurch)

5. The Result (effects/consequences)

7. Read the handout to find the answers to these questions
Task
Read the handout to find the answers to these questions
What made the earthquake worse?
What were the streets turned into?
Which department of Auckland Uni was Mr Pender from?
Which towns and cities could be affected by liquefaction?
What were large sections of Christchurch built on?
What things were unsettled by the water squirting through the soil?
What proportion of homes on the flat have been affected?
How many homes were ruined in Bexley?
How many tonnes of silt have risen to the surface in Christchurch?
Why were Christchurch’s sediments soft?

8. Vocab - Alluvium Soil created when rivers deposit sediment
It is often very fertile but not very solid
Prone to liquefaction
Therefore when an earthquake occurs near river plains then liquefaction is quite likely to occur

9. Summary – Discuss with your neighbour
What is it?
When did it happen?
How does it form?
Why did it occur in Christchurch?
Where did it happen in Christchurch?
What is the result?
Write your answers on a window

10. In Summary – Discuss with your neighbour
What is it? The process of soil turning into liquid
When did it happen? Immediately after the earthquake
How does it form? When violent shaking of sandy, saturated soil forces water between the grains, causing them to ‘float’
Why did it occur in Christchurch? Because much of the soil there is sandy and was saturated from the winter
Where did it happen in Christchurch? Mainly in the Eastern Suburbs like Bexley
What is the result? Liquefaction can have severe results for both the environment, and the built environment on top. Examples include roads, houses..