These two phenomenon need to be discussed separately.
The movement of two plate boundaries or more and the subsequent pressure that builds up following this movement is the major cause of earthquakes. An earthquake occurs as soon as the pressure eases off.
Whenever a plate boundary exists, earthquake is bound to happen because every plate moves in a particular direction which helps the buildup of pressure.
The movement of these plates is caused by convectional currents that cause the rising of hot air and the sinking of cool air.
The earth crust floats on the mantle, the magma in the mantle is made to move due to the action of the convectional current. The hot magma rises while the cooler magma sinks, and this leads to the movement of the earth crust because the earth crust floats on the same magma.
The process of an earthquake:
- When the crusts travel pass each other and a collision occurs in the process.
- Pressure builds up
- Pressure gets released
- The plates keep moving
- This release of the built-up of pressure and the movement of the plates are solely responsible for the earthquakes.
These are natural occurrences that happen when the magma contained in the mantle starts moving and escaping through the surface.
They can exclude the collision boundaries between different continental plates-convergent boundaries. They can also occur at hotspots or divergent plates boundary. Fold mountains and volcanoes are formed where there is a convergent boundary.
The process of an volcano eruption:
- Oceanic Plate sublets
- The crust dissolves into magma/molten rock
- Magma forms a volcano at the surface or in some cases island after its escape.
- Volcanic eruption occurs whenever the molten magma forcefully makes its way up the volcano.
Most earthquakes, but not all, have close relationships with volcanoes. For instance, most earthquakes happen along tectonic plate edges. This is the same place where most volcanoes are also located. However, earthquakes mostly happen as a result of interaction between the plates, rather than the movements of the magma.