From Wikipedia, the free encyclopedia

Fort Tejon earthquake

Date	January 9, 1857 (1857-01-09)
Magnitude	7.9 Mw
Depth	Less than 10 kilometres
Epicenter location	35°26′N 120°11′W / 35.43°N 120.19°W / 35.43; -120.19Coordinates: 35°26′N 120°11′W / 35.43°N 120.19°W / 35.43; -120.19[1]
Countries/ regions affected	USA
Casualties	2 killed[1]

The Fort Tejon earthquake occurred at about 8:20 AM (Pacific time) on January 9, 1857. It ruptured the San Andreas Fault for a length of about 225 miles (350 kilometers), between Parkfield and Wrightwood.^[1][2] The average slip along the fault was 4.5 meters (15 feet), and a maximum offset of 9 meters (30 feet) was recorded in the Carrizo Plain area.^[1] The amount of fault slip gives this earthquake a moment magnitude of 7.9, comparable to that of the 1906 San Francisco earthquake. Based on the (uncertain) distribution of foreshocks for this earthquake, it is assumed that the beginning of the fault rupture (the epicenter) was in the area between Parkfield and Cholame, about 60 miles northwest.^[1] Nevertheless, it is usually called the "Fort Tejon" earthquake because this was the location of the greatest damage, most of the area being unpopulated at the time.

Only two fatalities were recorded as a result of this earthquake, one was a woman who was killed by a collapsing adobe house at Reed's Ranch (Gorman), very close to the fault.^[1] Most of the buildings at Fort Tejon were badly damaged and several people were injured. Some buildings in Los Angeles were cracked but no major damage was reported. In Ventura the roof of Mission San Buenaventura fell in and the bell tower was damaged. Ground cracks from liquefaction of swampy ground were observed in Los Angeles and near Oxnard. The earthquake was felt as far south as the mouth of the Colorado River, as far north as Marysville and as far east as Las Vegas.^[2]

See also

• Earthquakes in California
• List of earthquakes in the United States

Notes

References

• Agnew DC, Sieh KE (1978). "A documentary study of the felt effects of the great California earthquake of 1857". Bulletin of the Seismological Society of America 68: 1717–1729.  
• Sieh KE (1978). "Slip along the San Andreas fault associated with the great 1857 earthquake". Bulletin of the Seismological Society of America 68: 1421–1448.  
• Sieh KE (1978). "Central California foreshocks of the great 1857 earthquake". Bulletin of the Seismological Society of America 68: 1731–1749.  

External links

• USGS Earthquake Hazards Program - 1857 Fort Tejon Earthquake
• Southern California Earthquake Data Center - 1857 Fort Tejon Earthquake
• Reports of the Great California Earthquake of 1857 - reprints contemporary accounts