What are the main causes of earthquakes?

Earthquakes are caused by a sudden release of stress along faults in the earth’s crust. The tectonic plates are always slowly moving, but they get stuck at their edges due to friction. When the stress on the edge overcomes the friction, there is an earthquake. The resulting waves of seismic energy propagate through the ground and over its surface, causing the shaking we perceive as earthquakes. The main causes of earthquakes are:

• Plate tectonics: They account for most earthquakes worldwide and usually occur at the boundaries of tectonic plates.
• Induced quakes: They are caused by human activity, like tunnel construction, filling reservoirs and implementing geothermal or fracking projects.
• Volcanic quakes: They are associated with active volcanism.
• Collapse quakes: They can be triggered by such phenomena as cave-ins, mostly in karst areas or close to mining facilities, as a result of subsidence.

Further Reading:

• Earthquake – Body Waves, Causes & Types 
• Geography Notes

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