In this article, we are discussing what cause earthquake. The main reasons such as natural causes and man-made cause are discussed in detail.
Having awareness of the earthquake is very important for engineers in different fields as the damage is not limited to civil construction works. It would cause severe to everything in the areas where they occur. However, taking preventive measures using expert knowledge would minimize or avoids the possible mages due to an earthquake.
There could be several reasons to earthquake to occur. It may be a natural or man induced reasons for earthquake as we identify the earthquake as the movement or shaking of the ground in the manner, we feel uncomfortable. Depending on the degree or the magnitude, the damage would be different.
What Cause Earthquake | Types of Earthquakes
As we discussed previously, the shaking of the ground can be identified as an earthquake. The following type of earthquake can be identified depending on the nature of occurrence.
- Induced Earthquake
- Collapse Earthquakes
- Volcanic Earthquakes
- Tectonic Earthquakes
Let’s discuss each type of earthquake to understand what cause earthquake.
Induced Earthquake
Humana activates cause the induced earthquakes. Stresses and strains induced by the human activity are commonly expressed as earthquakes and tremors.
Some of the causes of forming earthquakes are as follows.
- Inject fluid into earth deeper levels; Injection of the industrial by product such as carbon dioxide and wastewater produced in the oil and gas production. The Wikipedia article induced seismicity could be referred for further information on the formation of earthquakes and tremors.
- Extract fluid from the earth; Ground water extraction could cause induced earthquakes
- Mining
- Dam construction
- Tunnel Construction
Collapse Earthquakes
The majority of collapse earthquakes, which are often smaller, occur close to underground mines. The pressure that builds up inside the rocks causes collapse earthquakes. More shocks are caused by this type of earthquake, which causes the roof of the mine to fall. Little towns or cities close to underground mines frequently experience these types of earthquakes.
Volcanic Earthquakes
Volcanic earthquakes are on that big in magnitude when compared to the tectonic earthquakes.
Volcanic tremors happen beneath the eruption’s epicenter and occurs mostly close to the earth surface.
Tectonic Earthquakes
The type of earthquakes mostly occurs in the world due the relative movement between the plates.
There are seven plates in the world namely African plate, Antarctic plate, Eurasia plate, Indu-Australian plate, North American plate, Pacific plate and South American plate.
The relative movement of the generate the seismic waves as indicate in the following figure and they travel through the ground in the vertical and the horizontal directions.
A sudden slip on a fault results in an earthquake. Although the tectonic plates are constantly moving slowly, the friction between plates causes them stuck at the edges. An earthquake occurs when the stress on the edge exceeds the friction, releasing energy in waves that flow through the earth’s crust and produce the shaking we experience in the vertical and horizontal directions.
It creates the movement of the ground. Sometimes there is permanent deformation in the ground after an earthquake.
Design of structures to resist the earthquake is very important specially for the earthquakes caused by the movement plates as they generate very high ground accelerations that cause severe damage to the structures leading to loss of many lives.
The following articles could be referred for further information to understand what cause earthquake and important facts to be considered in structural design.
- UBC 1997 Seismic Design
- UBC 1997 Seismic Design Example
- Seismic Design [Things to be known]
- Seismic Design Principles – Factors to be Considered
- Seismic Detailing of Beams and Columns
- Seismic Earth Pressure Coefficient
Reference: Internet and books, and images are from internet