Editing Geography of California (section)

==Geology==
{{Main|Geology of California}}

===Faults, volcanoes, and tsunamis===
[[Earthquake]]s occur due to [[fault (geology)|faults]] that run the length of the Pacific coast, the largest being the [[San Andreas Fault]].  Major historical earthquakes include, with the magnitudes listed:
* [[1906 San Francisco earthquake]] (magnitude 7.8–8.2)
* [[1971 San Fernando earthquake]] (magnitude 6.6)
* [[1989 Loma Prieta earthquake]] (magnitude 6.9–7.1)
* [[1994 Northridge earthquake]] (magnitude 6.7)

Coastal cities are vulnerable to [[tsunami]]s from locally generated earthquakes as well as those elsewhere in the Pacific [[Ring of Fire]]. The [[Great Chilean earthquake]] tsunami (1960) killed one person and caused $500,000 to $1,000,000 of damage in [[Los Angeles]], damaged harbors in many coastal cities, and flooded streets in [[Crescent City, California|Crescent City]].<ref>[https://web.archive.org/web/20110427033753/http://wcatwc.arh.noaa.gov/web_tsus/19600522/damage.htm May 22, 1960 Tsunami<!-- Bot generated title -->]</ref> Waves from the Alaskan [[1964 Alaska earthquake|Good Friday earthquake]] of 1964 killed twelve people in Crescent City and caused damage as far south as Los Angeles. USGS has released the UCERF [[California earthquake forecast]] which models earthquake occurrence in California.

California is also home to several [[volcano]]es, including [[Lassen Peak]], which erupted in 1914 and 1921, and [[Mount Shasta]].

===Tectonics===
California, when only partially explored by the Spanish, was once thought to be an island, as when the southern [[Baja California peninsula]] is approached from the [[Gulf of California]] the land appears to the west. It is expected, through the motions of [[plate tectonics]] that the sea floor spreading now acting in the Gulf of California (also known as the Sea of Cortez) will eventually extend through Southern California and along the San Andreas fault to below [[San Francisco]], finally forming a long island in less than 150 million years. (For comparison, this is also the approximate age of the [[Atlantic Ocean]].) Predictions suggest that this island will eventually collide with [[Alaska]] after an additional 100 million years.