What are the primary effects of earthquakes?

The primary effects of earthquakes include ground shaking, surface rupture, and damage to buildings and infrastructure.

When an earthquake occurs, the most immediate and noticeable effect is ground shaking. This shaking is caused by the sudden release of energy in the Earth's crust, which generates seismic waves. The intensity of the shaking can vary greatly depending on the earthquake's magnitude, depth, and distance from the epicentre. Ground shaking can lead to the collapse of buildings, bridges, and other structures, posing a significant risk to human life and property.

Surface rupture is another primary effect of earthquakes. This happens when the ground along a fault line breaks and shifts during an earthquake. Surface rupture can create visible cracks and fissures in the Earth's surface, which can disrupt roads, railways, and pipelines. In some cases, the ground displacement can be several metres, making it difficult to repair the affected infrastructure quickly.

Damage to buildings and infrastructure is a major concern during earthquakes. Structures that are not designed to withstand seismic forces are particularly vulnerable. Older buildings, especially those made of unreinforced masonry, are at higher risk of collapsing. Modern buildings, however, are often constructed with earthquake-resistant designs, such as flexible materials and shock absorbers, to minimise damage. Despite these precautions, even well-designed buildings can suffer significant damage in a powerful earthquake.

In addition to these primary effects, earthquakes can also trigger secondary hazards such as landslides, tsunamis, and fires. Landslides can occur when the shaking destabilises slopes, causing large amounts of rock and soil to slide downhill. Tsunamis are giant sea waves generated by underwater earthquakes, which can inundate coastal areas and cause widespread destruction. Fires can break out due to ruptured gas lines or electrical faults caused by the shaking, further compounding the damage.

Understanding these primary effects is crucial for preparing for and mitigating the impacts of earthquakes, ensuring that communities can respond effectively when they occur.