Earthquakes

3. Why some people are at a higher risk to be affected by tropical cyclones than others

If you look at the map of the world (figure 8 on p. 33) on which the ground-plates are indicated, you will notice that we find some of the world’s most densely populated areas in these danger zones. Should an earthquake occur, many lives could be lost.

In developed countries or regions like Europe, the USA and Japan an earthquake’s damage can be limited and losses minimised. Buildings, bridges and roads are built to resist the effect of earthquakes. The infrastructure in such countries are highly sophisticated and their health care and medical services are immediately available in case of emergencies.

It is different, though, in developing countries. Many people die and constructions are easily destroyed. Buildings are usually erected in the cheapest possible way and cannot withstand the force of an earthquake. Thousands are left homeless, hungry and injured. The poor infrastructure prevents that aid reaches them soon enough. Corpses start decaying and drinking water is polluted, spreading disease which increases the number of deaths.

Activity 4:

To discuss the reason why people live in areas where earthquakes occur

[lo 2.2]

1. Why do people decide to live in areas where earthquakes occur? Take some time to think about this and then give your own opinion.

2. Where would you hide if an earthquake struck in your environment?

4. Precautionary measures: managing risk and reducing risk

Can earthquakes be forecast?

Unfortunately, this is not always possible. However, the earth’s crust is intensively studied and sensitive instruments register the slightest movement in the crust.

Scientists use special methods and apparatus, e.g. seismographs, to study and forecast earthquakes. A seismograph can detect any movement in the earth’s crust. When foreshocks occur scientists are able to detect activity in the earth’s crust and issue warnings in time. Some satellites are also equipped to pick up movement in the earth’s crust.

There are also other non-scientific signs in nature that, if observed in time, could help to forecast an earthquake, e.g.

• a sudden significant change in the level of groundwater (e.g. in wells);
• the sudden strange behaviour of animals.

If earthquakes could be forecast in time, warnings to evacuate the danger zones could be issued and so loss of life could be limited. Whether all people listen to such warnings is an open question.

Remember – not all earthquakes can be forecast. Some happen suddenly, without any foreshocks or other signs.

Activity 5:

To list emergency measures in case of an earthquake

[lo 2.3]

Imagine that you live in an area where earthquakes occur frequently (where there is a weak place in the earth’s crust). Draw up a list of emergency measures that should be applied before, during and after an earthquake.

Copy the world map from Figure 8 and indicate the areas where earthquakes occur on your own map. Then use red to colour in these areas.

Assessment