What phenomenon is described by the term "earthquake"?

The term "earthquake" specifically refers to the sudden shaking or trembling of the ground, which occurs as a result of the release of energy in the Earth's crust. This energy can be caused by the movement of tectonic plates, which often leads to the buildup of stress in the Earth's crust until it is released in the form of seismic waves. This shaking is what people typically experience during an earthquake and is measured by instruments such as seismometers.

While the shifting of tectonic plates underlies many earthquakes, the definition more accurately captures the immediate sensation of movement experienced by people. The other options do not describe the phenomenon of an earthquake; changing weather patterns pertain to meteorological conditions, while volcanic eruptions involve the expulsion of magma and gases from a volcano rather than ground shaking caused by tectonic activity.