Earthquakes

Memorandum

Activity 1:

1. Constructing a model

The teacher must provide two wooden planks of equal thickness and 7 - 9 building blocks made from cardboard. Follow the instructions as set out in Learning Unit 4, page 5, to carry out the experiment.

1. As the planks are drawn away from each other in opposite directions, the building blocks also start shifting. If the planks continue to move, the building blocks tumble down.
2. The two wooden planks represent two different layers constituting the earth’s crust. See Figure 8.
3. See cutting on earthquakes and the design of buildings and insert here to serve as memo. Learners may also give their opinions. **(See accompanying note for an answer.)

Activity 2:

Ask learners to trace the world map, using Figure 8. The teacher can also supply the learners with a world map (outline only). Learners indicate in red where earthquake areas are to be found on our planet.

Activity 3:

Many people die or are seriously injured;

Damages amounting to millions of rands occur;

Buildings collapse or severe damage is caused;

Tarred roads buckle and are ripped apart;

Bridges collapse;

Dam walls collapse or get damaged;

Fires break out because of electric cables and gas pipes that get amaged;

Power failures cause total blackouts;

Water streams from burst pipes and cause flooding and a shortage of fresh water;

Sewage pipes break and cause pollution, which cause health hazards;

Telephone connections are severed;

Mountain passes are blocked due to rock falls;

The country’s economy is severely affected. International aid is important for reconstruction.

1. b) Nature:

River courses change as a result of shifts in the earth’s crust. Consequently the natural environment also changes;

Topsoil along the mountain slopes become undone and start sliding down the slopes. Human beings and buildings might be buried under the landslides;

The natural vegetation is therefore destroyed and it may take many years to recover. In the meantime the lack of vegetation on the bare slopes increases the chances of soil erosion.

Floods and destruction occur in low-lying areas if an earthquake has originated under the sea-bed, causing a tsunami.

1. Learners bring photographs, pictures and newspaper cuttings on earthquakes to the classroom. They discuss these, adding some of the points to their notes.

3. Tsunami’s The Southern Asian tsunami of 26 December 2004.

Learners collect information on this.

See web page (External Link)

Activity 4:

1. Why do people live in these regions?

Earthquakes are not an everyday phenomenon. Some regions might experience an earthquake once in a lifetime. People therefore take a chance and hope that it will not occur again.

Many of the “endangered regions” are also important financial and industrial centres. There are many job opportunities and prosperity there. Financial implications are therefore important considerations.

Traditionally many generations have been living there (especially in developed countries) who do not move away easily.

2. What to do during an earthquake.

Advice is plentiful.

Leave the building immediately.

Move to the top storey immediately if you live in a high rise building so that the building does not collapse on you.

Avoid the lifts of tall buildings. You could be trapped in them.

Seek refuge under a concrete beam if available, otherwise under stealthy furniture such as tables.

Move to open fields immediately where there are no flying objects.

Activity 5:

1. Emergency measures before an earthquake

Listen to the radio or TV daily. If tremors in the crust of the earth are picked up, warnings will be transmitted immediately.

Always have a backpack ready containing fresh clothes, a blanket or warm clothing.

The following should also be included: a) fresh water

b) non-perishable foodstuffs

c) medicine

d) a flashlight

Always keep your personal documents ready.

2. Emergency measures during an earthquake.

Find a place of safety immediately or move to an open field.

3. Emergency measures after an earthquake.

Avoid snooping around in damaged buildings. Loose objects could fall and cause injuries.

Erect tent settlements for homeless people as temporary housing facilities until emergency personnel have completed their clearing up operations.

Erect temporary sewage and water supply points.

Erect temporary catering facilities.

Supply medical aid to people who have been injured.