What Causes Earthquakes?

Earthquakes are a natural phenomenon that occur when the tectonic plates beneath the Earth’s surface shift and release energy. This energy creates seismic waves, which travel through the Earth and can be felt as tremors and vibrations on the surface. The point at which the tectonic plates meet and energy is released is known as the focus of an earthquake.

One of the main causes of earthquakes is the friction between tectonic plates as they move and shift against each other. This friction builds up over time, creating pressure and stress within the Earth’s crust. When this stress becomes too great, the tectonic plates will suddenly slip and release energy in the form of an earthquake.

Seismic waves are another important factor in causing earthquakes. These waves are created when the energy from an earthquake is released and travels through the Earth’s crust. The energy from seismic waves can be felt far from the focus of an earthquake and can cause significant damage to buildings, roads, and other infrastructure.

In addition to tectonic activity, earthquakes can also be caused by other factors such as volcanic activity, landslides, and man-made events such as underground explosions. Understanding the causes of earthquakes is crucial for predicting, protecting, and preparing for future earthquakes. The type of tectonic plate movement that causes an earthquake can determine its intensity and impact.

For example, a conservative plate boundary involves two plates that are moving past each other. This type of movement creates a lot of friction and pressure, which can result in destructive earthquakes. A destructive plate boundary involves two plates that are moving towards each other. When one plate is forced beneath the other, it can create a significant amount of pressure and lead to earthquakes. Conversely, a constructive plate boundary involves two plates that are moving apart from each other. While these types of movements can still create seismic waves, they typically result in less intense earthquakes.

The focus of an earthquake is the exact point within the Earth’s crust where energy is released. This is different from the epicentre, which is the point on the surface directly above the focus. The focus of an earthquake can be located at different depths within the Earth’s crust, and this can also affect the intensity and impact of the earthquake.

Understanding the causes of earthquakes and the different types of tectonic plate movement is an important first step in preparing for future earthquakes. In the next sections, we will explore the effects of earthquakes and how we can predict, protect, and prepare for them using case studies from Christchurch and Haiti.