What are aftershocks most likely due to?

Aftershocks are most likely a result of slip around irregularities on the fault surface. When an initial earthquake occurs, the tectonic strain is released along the fault line, but the fault surface may not be perfectly smooth. Irregularities or rough spots on the fault can prevent it from slipping uniformly during the earthquake. As the ground stabilizes following the main shock, these irregularities may cause additional, smaller slips, leading to aftershocks.

This relationship is a key aspect of seismic activity; the aftershocks serve as a way for the fault system to adjust and release any remaining stress along the fault line. Over time, the intensity and frequency of aftershocks typically diminish as the system stabilizes. Other processes mentioned in the choices, such as the formation of new faults or volcanic activity, do not typically account for the immediate succession of smaller tremors that follow a large earthquake. Seismic gaps refer to areas along a fault where earthquakes have not occurred for a long time, often suggesting potential future seismic activity, but they do not directly cause aftershocks.