Flashcards in Earthquakes, Their Global Distribution And Their Consequences Deck (15)
Define an earthquake.
A shock or series of shocks caused by sudden movements of the Earth's crust
Define the focus of an earthquake.
The point in the Earth's crust where the earthquake occurs; the origin of seismic energy.
Define the epicentre of an earthquake.
The point on the Earth's surface directly above the focus where an earthquake's effects are felt first.
Define a seismograph.
An instrument that records an earthquake's shockwaves.
Define the Richter Scale.
The chart on which the magnitude of an earthquake is measured.
Describe the general global pattern of earthquakes.
Earthquakes are often linear - they are found in lines or zones.
They occur near plate margins.
Which places on the Earth are earthquakes mainly found? 
1. Around the Pacific Ocean, a part of the 'Ring of Fire'
2. In a north-south line through the middle of the Atlantic Ocean
3. In an east-west line across southern Europe, the Himalayas and South East Asia.
What is the 'Ring of Fire'?
A major area of the Pacific Ocean where many earthquakes and volcanic eruptions occur.
Why do earthquakes occur at plate margins?
This is where friction occurs and pressure builds up as plates move past each other.
What are the two main physical consequences of earthquakes?
Explain the process of liquefaction. 
1. Liquefaction occurs when rock or soil containing water is shaken by an earthquake.
2. This causes the water to rise to the surface and turn the soil into liquid mud.
3. Any buildings resting on the soil collapse.
Define a tsunami.
A large wave of seawater caused by an earthquake under the sea.
Explain the process of a tsunami. 
1. Tsunamis are caused by earthquakes under the sea.
2. Shockwaves from plate movement create small, roughly 30 cm high waves.
3. As the waves move towards the shore and into shallower water, they become much larger, up to 30 m high.
How can you tell if a tsunami is approaching without seeing it?
A dramatic fall in sea level can be observed on the shore.