Describe the primary and secondary effects of an earthquake. (4 marks)

An earthquake is a natural phenomenon that occurs when there is sudden movement along a fault in the earth’s crust. The primary effects of an earthquake are the immediate and direct consequences of the shaking and ground rupture caused by the seismic waves. The secondary effects are the indirect consequences that occur after the earthquake has stopped.

Primary Effects:

1. Ground shaking: The shaking caused by the earthquake can cause significant damage to buildings, infrastructure, and other structures. It can also trigger landslides, rockfalls, and avalanches.
2. Ground rupture: The movement along a fault can cause the ground to rupture, resulting in cracks and fissures on the surface.
3. Tsunami: In some cases, large earthquakes that occur beneath the ocean can cause a tsunami, a series of ocean waves that can travel long distances and cause significant damage.
4. Human casualties: The primary effects of an earthquake can result in injuries and deaths to humans and animals in the affected areas.

Secondary Effects:

1. Aftershocks: After the initial earthquake, smaller earthquakes called aftershocks can occur, which can cause further damage to structures that were already weakened.
2. Fires: Earthquakes can damage gas lines and electrical wiring, which can lead to fires that can cause additional damage and casualties.
3. Liquefaction: The shaking of the ground can cause soil to lose strength and become more fluid-like, resulting in the sinking or shifting of buildings and infrastructure.
4. Economic impact: Earthquakes can cause significant economic losses due to damage to infrastructure, buildings, and loss of productivity.