Earthquakes Flashcards
Where is there not a lot of earthquakes?
Africa, specifically South Africa
Why do we not experience a lot of earthquakes?
We are on the thickest part of the crust
Do earthquakes only occur on land?
no
What do underwater earthquakes cause?
Tsunamis
Is it likely to experience a tsunami in South Africa?
no, you will probably never experience a tsunami if you live in south africa
How do earthquakes occur?
When the ground is subjected to so much force that it fractures or breaks
Do Tectonic plates move fast?
No
How do tectonic plates get stuck on each other
the friction on the edge needs to overcome the friction thus, an earthquake occurs releasing energy in waves that travel through the earths crust and causes the shaking we feel
Where do earthquakes happen?
Where the crust is weak
How are seismic waves created?
There are movements in the earths crust and shockwaves move from that point outwards
What is the focus?
The point under the ground where the earthquake start
Where is the epicenter?
It is the point directly above the focus on the surface of the earth
Where do most earthquakes occur?
Along faults that are cracks in the earths surface
What happens after the main quake?
There are usually several aftershocks or smaller earthquakes
What is a tremor?
A tremor is a slight or mild earthquake that usually causes little or no damage
What are 4 of the effects of earthquakes?
Water supplies can be destroyed and contaminated which can lead to diseases like cholera which can lead to more deaths, people have nowhere to live as there houses have been destroyed, broken electrical wires can cause fires, Tsunamis can be caused and can kill many people
What two factors decide the why earthquakes cause more damage to some communities than others?
How well the buildings were made and how the rescue plans and equipment made available
What is a quake proof house have that a “normal” house doesn’t?
Hollow concrete bricks designed to cause minimal damage if they fall, a roof made from reinforced cement concrete, a foundation made from stone made from destroyed house and reinforced corner pillars providing strength and flexability
What is a seismograph and what does it do?
A seismograph is a scientific instrument which measures the movements of the earths surface
