Asperities on a Strike-slip Fault

Does a fault break all at once?

Oblique view of a right-lateral strike-slip fault with multiple asperities. When one asperity slips, there is an added load on the adjoining asperities. In a large earthquake there is a cascading effect as each zone that slips loads the next zone, which then slips, and so forth, sometime for hundreds of miles, in a process that can continue for 5 or more minutes. An asperity is an area on a fault that is stuck or locked. Scientists study areas along long fault zones that have not had earthquakes in a long time in order to determine where the next earthquake may occur; as long faults move, all areas of it will, at some point, become "unstuck" causing an earthquake relative to the the size of the asperity that finally breaks.


Keypoints:

  • An asperity is an area on a fault that is stuck or locked.
  • An area along an active fault that has not had an earthquake in a long time might be vulnerable to a large earthquake.
  • In a large earthquake there is a cascading effect as each zone that slips loads the next zone.
  • The earthquake rupture often begins at an asperity

Total Time: 28s
Level: Novice

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