Chapter 3 - Earthquakes Flashcards
Define earthquake.
An earthquake is a series of seismic waves that shake the ground and buildings.
How are earthquakes caused?
Earthquakes are caused when plates collide, slide past each other or separate. Pressure builds up between two plates and this forces the rock to break. An earthquake results from this - the surface of the crust may just shake or be moved up by several metres.
Define the focus.
The focus is the place within the crust where the rock breaks and the earthquake begins, sending out shock waves or seismic waves.
Define the epicentre.
The epicentre is on the surface directly above the focus. It is where the most severs shocks occur.
Define aftershocks.
Usually after an earthquake, the area will experience aftershocks (smaller tremors), which can often cause further damage to already weakened buildings.
Define a fault line.
A fault or fault line is a crack in the earth’s surface.
Define seismic waves.
The seismic waves are the vibrations that are sent out by the earthquake and which cause buildings to collapse.
Define seismographs.
Seismographs are machines used to measure the shocks (or vibrations) caused by earthquakes.
The Richter Scale.
What is the force of earthquakes measured on?
Name two countries in the world where earthquakes occur.
Japan and China
What impact did the 2011 earthquake and tsunami have on Japan?
The earthquake raised the seabed by about 8 metres, resulting in HUGE tsunami waves of up to 40 metres in height reaching the coast of Japan.
Explain what a tsunami is and how they are made.
A tsunami is a huge, dangerous wave caused by an undersea earthquake.
Describe the effect an earthquake has on roads and buildings.
Buildings can collapse and roads can break in two. The ground can be moved several metres. People can be trapped inside buildings.
