An aftershock is an earthquake that follows
the largest shock of an earthquake sequence. Aftershocks are smaller than
the main shock and within 1–2 fault lengths distance from the main shock
fault. Aftershocks can continue over a period of weeks, months, or years.
In general, the larger the main shock, the larger and more numerous the aftershocks,
and the longer they will continue.
|The Landers fault (red lines at left) and the Hector
Mine fault and its aftershocks (red lines and circles at right). The
Hector Mine earthquake was a magnitude 7.1, and it produced thousands
of aftershocks. Image credit: Egill Hauksson, Caltech
AND PLANETARY SCIENCE
Source: U.S. Geological