2.2.2 Earthquakes

Earthquakes occur on all plate boundaries as a result of what?

• Volcanic eruptions

• Plate movement and frictional forces building up stress in the fault

• Gravitational pull from the moon

• Changes in atmospheric pressure

Answer explanation

Earthquakes occur on all plate boundaries as a result of plate movement and frictional forces building up stress in the fault.

What is the term used for the point in the fault from where stress is released during an earthquake?

• Epicentre

• Mantle

• Focus

• Seismic zone

Answer explanation

The term used for the point in the fault from where stress is released during an earthquake is called the 'Focus'. It is the initial point where the seismic waves originate.

What moves outwards from the focus in all directions during an earthquake?

• Lava flows

• Seismic waves

• Tsunami waves

• Wind gusts

Answer explanation

Seismic waves move outwards from the focus in all directions during an earthquake, not lava flows, tsunami waves, or wind gusts.

What is the point on the surface directly above the focus of an earthquake called?

• Mantle

• Epicentre

• Core

• Crust

Answer explanation

The point on the surface directly above the focus of an earthquake is called the Epicentre, making it the correct choice.

Where is most destruction likely to take place during an earthquake?

• At the focus

• At the epicentre

• In the mantle

• Along the fault lines

Answer explanation

Most destruction is likely to take place at the epicentre of an earthquake, where the seismic waves are strongest and the surface is directly above the focus of the earthquake.

Which type of seismic waves are the fastest travelling and arrive first?

• Secondary Waves

• Surface Waves

• Primary Waves

• Tertiary Waves

Answer explanation

Primary Waves are the fastest travelling seismic waves and arrive first, making them the correct choice.

Secondary waves move in a way that is:

• Compressional and parallel to the direction of movement

• Compressional and perpendicular to the direction of movement

• Rolling and parallel to the direction of movement

• Rolling and perpendicular to the direction of movement

Answer explanation

Secondary waves move in a rolling motion that is perpendicular to the direction of movement, not compressional or parallel.

Surface waves are described as being most destructive and:

• Travel through land and water

• Travel only through the crust

• Arrive first before other waves

• Move in a rolling wave parallel to the direction of movement

Answer explanation

Surface waves are most destructive and travel only through the crust, making them unique in their behavior compared to other types of waves.

How are surface waves described in terms of their movement?

• Like going down the stairs on your bike

• Like riding a wave in the ocean

• Like a smooth glide on a flat surface

• Like a rapid ascent on a steep hill

Answer explanation

Surface waves are described as moving like going down the stairs on your bike, not like riding a wave in the ocean, a smooth glide on a flat surface, or a rapid ascent on a steep hill.

What does the magnitude of an earthquake refer to?

• The location of the earthquake's origin

• The physical size of an earthquake in terms of the intensity of shaking

• The duration of the earthquake

• The number of aftershocks following the earthquake

Answer explanation

The magnitude of an earthquake refers to the physical size of the earthquake in terms of the intensity of shaking.