One Effect Many Causes

An earthquake is the shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth's lithosphere that creates seismic waves.Earthquakes develop simply when the underground rocks (plate tectonics) unexpectedly break along fault lines. Earthquakes are measured using observations from seismometers. Earthquakes are, thus, caused by tectonic plate movements, volcanic activity or underground explosions.Plate tectonic movements cause the majority of the earthquakes. The movements occur because the plates float on the hotter and denser rock of the mantle. Consequently, these plates are usually in constant movement – past or from each other within the earth’s crust. Apart from tectonic plate movements, volcanic activity can significantly cause massive earthquakes. Earthquakes normally accompany escaping magma as it rises to the crust during a volcanic eruption. This is mainly due to the sudden displacement and shaking of underground rocks. Seismic waves (wave shocks) similar to the ones causing earthquakes can be generated by underground explosions. These explosions can be as a result of underground mining or during the construction of railroads, subways, or underground tunnels. However, some of the seismic waves produced by these activities are not as strong as those produced by real earthquakes.