Plate Tectonics Questions Medium
Earthquakes occur due to the movement and interaction of tectonic plates, which make up the Earth's outer shell. The Earth's crust is divided into several large and small plates that float on the semi-fluid layer beneath, known as the asthenosphere. These plates are constantly moving, albeit very slowly, due to the convective currents in the underlying mantle.
When two tectonic plates interact, they can either move apart (divergent boundary), move towards each other (convergent boundary), or slide past each other horizontally (transform boundary). Most earthquakes occur at plate boundaries, particularly along the convergent and transform boundaries.
At convergent boundaries, where two plates collide, one plate is usually forced beneath the other in a process called subduction. As the subducting plate sinks into the mantle, it generates intense pressure and friction, causing the rocks to deform and accumulate stress. Eventually, the stress becomes too great, and the accumulated energy is released in the form of seismic waves, resulting in an earthquake.
At transform boundaries, where two plates slide past each other horizontally, the rocks on either side of the fault line become locked due to friction. As the plates continue to move, stress builds up along the fault line until it exceeds the strength of the rocks, causing them to slip suddenly. This sudden release of energy generates seismic waves, leading to an earthquake.
Earthquakes can also occur within plates, away from plate boundaries, although they are less frequent. These are known as intraplate earthquakes and are often associated with ancient faults or weak zones within the Earth's crust.
In summary, earthquakes occur due to the release of accumulated stress and energy along plate boundaries or within plates, resulting from the movement and interaction of tectonic plates.