Fort Tejon earthquake
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| Date | January 9, 1857 |
|---|---|
| Magnitude | 7.9 Mw |
| Depth: | Less than 10 kilometres |
| Epicenter location: | [1] |
| Countries/ regions affected |
 USA |
| Casualties: | 2 killed[2] |
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 350 kilometers (225 miles), between Parkfield and San Bernardino. Displacement along the fault was as much as 9 meters (30 feet) in the Carrizo Plain but less along the Palmdale section of the fault, closest to Los Angeles. 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. 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 from a collapsing adobe house at Reed's Ranch (Gorman), very close to the fault. 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 collapsed. 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.
[edit] 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
[edit] References
- ^ Southern California Earthquake Center SCEDC Fort Tejon Earthquake (1857)
- ^ Southern California Earthquake Center SCEDC Fort Tejon Earthquake (1857)
- 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.
