Earthquakes can cause terrible damage

In 2015 an earthquake hit Nepal. ‘Quake’ means shaking. So, an earthquake is a shaking of the Earth. More than 9000 people died and 23 000 people were injured. The first photograph shows the damage to buildings done by this earthquake. The second photograph shows damage to railway lines after an earthquake in Mexico in 2017. The terrible damage in these photographs is caused by earthquakes.
There are about 500 000 earthquakes each year around the world. Many of these earthquakes are so small that people don’t notice them. But about 100 earthquakes a year are so strong that they cause damage like the scenes shown in the photographs. They also cause landslides, which are when soil and mud slide down slopes. The soil and mud can cover towns and crops.

How do earthquakes happen ?

Earthquakes happen when there are sudden movements of rocks in the Earth’s crust. The Earth’s crust is made up of huge pieces of flat rock. Where two of these pieces meet, they rub together. This movement creates huge amounts of energy. The energy changes, or transfers, into waves. The waves travel through the crust to the Earth’s surface. We feel these waves on the Earth’s surface as an earthquake.

Look at the model of how an earthquake happens. The diagram shows a piece of the Earth’s crust. The focus is where the earthquake begins inside the crust. Waves of energy pass through the crust and on to the surface. The worst damage at the surface is experienced immediately above the focus at a point called the epicentre.

Which parts of the world are at risk of having earthquakes?

The parts of the world at risk of having earthquakes are the same areas that have a high risk of volcanoes. Both volcanoes and earthquakes happen where the rocks of the crust are broken and moving. Most earthquakes happen in the Pacific Ring of Fire.

Tsunamis

Atsunami is a huge sea wave. A tsunami happens when there is an earthquake or a volcanic eruption under the sea. The energy from the earthquake transfers to the sea to make huge waves. Sea waves increase in height when they reach shallow water. So when a tsunami reaches a shallow coastal area, the area along the border between the land and the sea, the wave can reach a height of 50 metres. This huge wave causes flooding of coastal areas.