[san an-drey-uh
s] 
| an active strike-slip fault in W United States, extending from San Francisco to S California and forming the on-land portion of the western margin of the North American Plate. |
| San An·dre·as Fault (sān ān-drā'əs) A major zone of fractures in the earth's crust extending along the coastline of California from the northwest part of the state to the Gulf of California. Movement of the tectonic plates along the fault has caused numerous tremors, including the devastating San Francisco earthquake of 1906. |
A major geologic fault located in California. It runs from San Francisco to near San Diego and has been the source of serious earthquakes. (See also under “Earth Sciences.”)
A fault in California where the North American and the Pacific tectonic plates meet and slide past each other. (See earthquake and plate tectonics.)
Note: A major earthquake along this fault has been predicted for many years. Because California is densely populated, such an event might have very serious consequences.