What is the term for the shock or movement that occurs after the main earthquake?

The term for the shock or movement that occurs after the main earthquake is "aftershock." Aftershocks are smaller seismic events that follow the initial quake and are a natural part of the earthquake process. These phenomena occur due to the continued adjustment of the Earth’s crust as it settles after the main event.

In contrast to the main shock of an earthquake, aftershocks can vary in strength, sometimes occurring days, weeks, or even months after the primary earthquake. They can be significant enough to cause additional damage, which is why it's important for communities to be prepared for these secondary events.

The other terms, while related to seismic activity, refer to different concepts. The epicenter refers to the point on the Earth's surface directly above where the earthquake originates. Tremors are generally lower-intensity vibrations that can occur at any time, not specifically linked to the aftermath of a major quake. Aftermath describes the consequences and damage that occur following a disaster, without specifically referencing the seismic activity itself.