Earthquakes

Question 1

What are the people called who study earthquakes?

Answer 1

Seismologists are scientists who study earthquakes.

Question 2

What is an earthquake?

Answer 2

An earthquake is the sudden shaking of the earth caused by the movement of the earth’s crust.

Question 3

Focus definition

Answer 3

The place where an earthquake begins beneath the earth’s surface

Question 4

Shock waves definition

Answer 4

Also called seismic waves. These spread out in circles from the focus.

Question 5

Epicentre definition

Answer 5

The point at the earth’s surface that is directly above the focus of the earthquake. The strength of the earthquake is greatest here.

Question 6

Fault definition

Answer 6

A large crack in the earth’s crust

Question 7

How does a tsunami happen? (3)

Answer 7

1. An undersea earthquake disturbs the seabed and causes powerful waves to move out very quickly in all directions.
2. The sea waves become much higher as they approach shallow water’s near the coast. They can be up to 30 metres high as they crash onto the shore.
3. A tsunami can devastate low-lying coastal areas.

Question 8

What is the San Andreas fault?

Answer 8

The San Andreas Fault in California is a large crack in the earth’s crust which makes part of a plate boundary.

Question 9

What can an earthquake under the sea trigger?

Answer 9

When an earthquake occurs under the sea, it can trigger a tsunami.

Question 10

What is a tsunami?

Answer 10

A tsunami is a huge wave that moves very quickly towards the shore. These waves can cause a huge amount of damage along the coastline and can result in many deaths.

Question 11

How are earthquakes measured?

Answer 11

Seismograph:
The instrument used to measure and record an earthquake and how long it lasted.
Richter Scale:
A scale sued to measure the magnitude of an earthquake. This scale goes from 1 to 8. Each one-unit increase means that the earthquake is 10 times more powerful than it was at the previous unit. It is unreliable for larger earthquakes.
Moment magnitude scale:
The moment magnitude scale (MMS) is used to measure the magnitude of earthquakes as it is more reliable for larger earthquakes. The scale goes from 1 to 10.

Question 12

N.E.E.D. earthquake

Answer 12

Example: Nepal earthquake (2015)

Question 13

Social and economic impacts of earthquakes

Answer 13

Social impacts:
People can be killed and injured.
Electricity, water supplies, sewage systems and communication networks can be affected.
Buildings can be destroyed such as clinics and schools.
Earthquakes can trigger other natural disasters like landslides and tsunamis.

Economic impacts:
Costs of damages can be very high.
Children and adults may no longer have schools to attend or homes to live in.
Large numbers of people will need emergency aid like food, water, medical supplies and tents.

Question 14

How can earthquake damage be reduced? (3)

Answer 14

1. Predicting when an earthquake might occur.
2. Planning for earthquakes
3. Construction of earthquake-safe buildings e.g. Torre Mayor skyscraper in Mexico City.

Question 15

List some examples of earthquake-proof systems in buildings

Answer 15

Rubber shock-absorbers under the building to absorb earth tremors.
Foundation sunk into bedrock, avoiding clay.
Fire-resistant building materials.
Automatic window shutters to prevent falling glass.
Steel frames that can sway during earth movements.
Computer-controlled weights on the roof to reduce movement.
Outer panels flexibility attached to steel structure.