1857 Fort Tejon earthquake

The 1857 Fort Tejon earthquake occurred at about 8:20 a.m. (Pacific time) on January 9 in central and Southern California. One of the largest recorded earthquakes in the United States,[6] with an estimated moment magnitude of 7.9, it ruptured the southern part of the San Andreas Fault for a length of about 225 miles (350 kilometers), between Parkfield and Wrightwood.

Though the shock was centered near Parkfield, the event is referred to as the Fort Tejon earthquake, because that was the location of the greatest damage. Fort Tejon is just north of the junction of the San Andreas and Garlock Faults, where the Tehachapi, San Emigdio, and Sierra Pelona Transverse Ranges come together.

The earthquake is the most recent large event to occur along that portion of the San Andreas Fault, and is estimated to have had a maximum perceived intensity of IX (Violent) on the Modified Mercalli scale (MM) near Fort Tejon in the Tehachapi Mountains, and along the San Andreas Fault from Mil Potrero (near Pine Mountain Club) in the San Emigdio Mountains to Lake Hughes in the Sierra Pelona Mountains. Accounts of the events' effects varied widely, including the time of the main shock as well as foreshocks that occurred at several locations earlier in the morning.

1857 Fort Tejon earthquake
1857 Fort Tejon earthquake is located in California
Los Angeles
Los Angeles
Fort Tejon
Fort Tejon
1857 Fort Tejon earthquake
Local date January 9, 1857
Local time08:20
Duration1–3 minutes[1]
Magnitude7.9 Mw[1][2]
Depth< 10 kilometers
Epicenter35°42′N 120°18′W / 35.7°N 120.3°WCoordinates: 35°42′N 120°18′W / 35.7°N 120.3°W[1]
FaultSan Andreas Fault
Areas affectedCentral California
Southern California
United States
Total damageSevere[3]
Max. intensityIX (Violent)[4]
Casualties2 killed[5]

Tectonic setting

The 1857 earthquake ruptured about 350 kilometers (220 mi) of the southern part of the San Andreas Fault, the structure that accommodates most of the displacement along the transform boundary between the North American Plate and the Pacific Plate. The Pacific Plate is moving north relative to the Sierra Nevada-Great Valley Block of the North American Plate at about 38 millimeters (1.5 in) per year.[7] The displacement rate along the various sections that ruptured is 34 millimeters (1.3 in) per year along the Parkfield, Cholame, Carrizo and Big Bend sections and 27 millimeters (1.1 in) and 29 millimeters (1.1 in) per year along the Mojave north and Mojave south sections.[8] Paleoseismic studies have found evidence for many prehistoric earthquakes in the last 3,000 years on this part of the San Andreas Fault.[9]


The earthquake ruptured a substantial portion of the southern San Andreas fault, but not the entire length. Thomas H. Jordan, director of the Southern California Earthquake Center, stated that the slip likely stopped in the area near Cajon Pass, perhaps because the tectonic stresses on that part of the fault had been released several decades earlier during the 1812 Wrightwood earthquake.[10] The average slip along the fault was 4.5 meters (15 ft), and a maximum offset of 6 meters (20 ft) was recorded in the Carrizo Plain area in southeastern San Luis Obispo County.[11] [12] With an estimated magnitude of 7.9, this was the last "Big One" in Southern California. The extreme southernmost portion of the San Andreas fault, which terminates near Bombay Beach at the Salton Sea, last ruptured in 1680.[2]

Surface faulting may have extended beyond the boundaries of the regularly acknowledged slip length. Researchers recorded first and second-hand accounts of the ground crack, which was understood to be recent surface faulting and not just the topography of the existing rift. On the extreme northern end of the rupture zone, the surface cracking extended 80 kilometers (50 mi) north of Cholame into San Benito County. On the southern end, the population centers were not as close to the fault, and early observers were probably limited to the stretch of the fault between Fort Tejon and Elizabeth Lake, as that was close to the Stockton – Los Angeles Road, the primary inland north−south route then.[13]

Evidence of uprooted and displaced trees south of Elizabeth Lake indicates surface faulting along a mole track (an "array of en echelon primary Riedel shears with linking compressional rolls and minor thrusts")[14] that ran directly under three Jeffrey Pines. Two of the three trees examined were tilted in their lower extremity, while the upper portions remained relatively untilted. Tree ring dating confirmed that the trees had originated 10 and 25 years before 1857 and also that the rings began to grow twice as thick on the side in the direction of the tilt. This is a frequently noted compensation of tree tilt. Seismologist Kerry Sieh determined that fault slip and the associated ground disturbance was the source of the mole track and subsequent tree tilt.[13]


USGS isoseismal map - 1857 Fort Tejon earthquake
An isoseismal map for the main shock

Various accounts of the event indicate the presence of foreshocks between one and nine hours before the main event,[15] and based on the (uncertain) distribution of those shocks, it is assumed that the beginning of the fault rupture (the epicenter) was in the area between Parkfield and Cholame, about 97 kilometers (60 mi) northwest.[16]

The lack of standardized timekeeping during this period of California's history contributed to some of the inaccurate reports of when the pre-shocks occurred. Local solar time was being used in 1857 and San Francisco would have been the locality with the most accurate time kept as it was a center of commerce and other activity. Standard time was not followed until the 1880s, with the Pacific Time Zone being aligned with the 120th meridian. The differences in local times were substantial, with San Francisco at 122.43 W and San Diego at 117.10 W, the difference between the two would be around 22 minutes (4 minutes per degree).[17] At least one individual reported foreshock times that varied by as much as half an hour when speaking to two different newspapers.[18]

The firsthand reports were most abundant for the shocks felt at 1, 2, and 4 hours before the main shock which were later labeled the predawn, dawn, and sunrise shocks. The predawn event shook residents of San Francisco (MM II – III), San Jose (MM IV), and Santa Cruz (MM IV). The dawn shock was felt in those locales plus Fort Tejon and possibly the Carrizo Plain. The sunrise shock was felt in San Francisco (MM III), Monterey (MM IV), and Visalia (MM II – III). Sacramento and Los Angeles did not report any of these events.[19]

Several mid-twentieth-century earthquakes had similar felt reports to the dawn and sunrise shocks and with close inspection, Sieh theorizes that both events were local to coastal central California, probably between Point Conception and Monterey. Also, during that period, no central California earthquake with a magnitude of less than five had a felt area as large as the two foreshocks, while events larger than magnitude six have had "somewhat larger" felt areas, so it could be said that the foreshocks most likely were between magnitude five and six.[20]

Parkfield earthquakes occurred with exceptionally regular intervals (between 20 and 30 years) between 1857 and 1966.[21] Sieh studied four of these events (1901, 1922, 1934, and 1966) and found that they helped to determine the southeast boundary for the origination of the dawn foreshock. The coverage and intensities of felt reports for that earthquake show a solid resemblance to the Parkfield events.[20] Only one of the four Parkfield events was not felt further southeast than the dawn shock, so Sieh concluded that if the San Andreas was the source of the event, then it was reasonable to assume that the Parkfield to Cholame stretch of the fault was responsible for producing the dawn felt intensities,[22] though the San Andreas is not the only possible source for the dawn event. For example, the November 22, 1952, magnitude six Bryson earthquake "nearly duplicates" the felt reports.[23] That event may have occurred west of the San Andreas on the Nacimiento fault, though the highest felt reports were along the Rinconada fault around 56 kilometers (35 mi) southwest of the San Andreas.


Most of the adobe buildings at Fort Tejon were badly damaged and several people were injured there. More buildings were destroyed along a twenty-mile stretch between Fort Tejon and southeast to Elizabeth Lake, a sag pond that was formed directly on the San Andreas fault. Streams and springs experienced disturbances in San Diego and Santa Barbara Counties, while the Kern River, Kern Lake, and Los Angeles River all spilled over their banks. Farther north in Santa Clara County the flow of well water was affected. Ground cracks from liquefaction of swampy ground were observed near the Pueblo de Los Angeles and in the Oxnard Plain, and ground fissures were reported near the Los Angeles, Santa Ana, and Santa Clara Rivers.[1]

Central and southern California were thinly populated at the time and this likely helped limit the damage from the earthquake, but the lack of people present also reduced the number of perspectives to use in determining intensity estimates. Areas with the highest population density like San Francisco, Stockton, and Los Angeles provided enough information about the effects of the earthquake to provide the best estimates of intensity. At downtown Los Angeles, with a maximum perceived intensity of VI, some homes and buildings were cracked, but no major damage was reported. In Ventura (MM VII) the roof of Mission San Buenaventura collapsed and the bell tower was damaged, and farther north, the front wall of the old adobe Mission Santa Cruz chapel collapsed. One of the two deaths reported included a woman who was killed by a collapsing adobe house in nearby Gorman, and an elderly man may have collapsed and died in the Los Angeles area as a result of the earthquake.[16][24][25]


The mainshock was followed by a series of aftershocks that continued for at least 3.75 years, although the total number of large aftershocks was less than would be expected for an earthquake of this size. The four largest aftershocks all had magnitudes greater than 6, although there are large uncertainties in both location and magnitude due to the limited number of data points available. On the night of January 9 there was a large aftershock with an estimated magnitude of about 6.25, with a possible epicenter near the Garlock Fault. The largest aftershock occurred on the afternoon of January 16 with an estimated magnitude of about 6.7, with a possible offshore location,[26] and high felt intensities in Southern California communities. Santa Barbara and San Bernardino reported an MM intensity of V and Los Angeles reported V and VI.[17] Two significant events occurred in the San Bernardino area on December 15–16, 1858, with the latter having an estimated magnitude of about 6. The last recorded major aftershock occurred on April 16, 1860, with an estimated magnitude of about 6.3, with an epicenter close to the Parkfield section of the San Andreas Fault.[26]

Future threat

Scientists and public service officials have speculated on the threat of another very large earthquake occurring in southern California and what type and scale of damage might result. The portion of the fault that ruptured in 1857 has settled into a period of dormancy and this has given rise to suggestions that future slip along that zone may be characterized by a very large 1857-type event followed by another period of inactivity.[27] The communities of Frazier Park, Palmdale, and Wrightwood are all located very close to the San Andreas fault, though much of the Los Angeles area could be affected even at a greater distance from the rupture area if a similar event were to reoccur there. Swaminathan Krishnan, assistant professor of civil engineering and geophysics at the California Institute of Technology, said that if a similar rupture from Parkfield to Wrightwood were to happen again, it would severely affect the Los Angeles area, with the San Fernando Valley being particularly hard hit.[28]

The Los Angeles Aqueduct and California Aqueduct, two of the principal water transfer infrastructure systems supplying Greater Los Angeles, both cross the San Andreas fault within the main damage zone of the Fort Tejon earthquake, in the Tehachapi and Sierra Pelona Mountains.

See also


  1. ^ a b c d Stover, C. W.; Coffman, J. L. (1993), Seismicity of the United States, 1568–1989 (Revised), U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, pp. 72, 101, 102
  2. ^ a b Jordan, Thomas (January 9, 2007). "Overdue and unprepared for the Big One". Los Angeles Times. Retrieved December 16, 2012.
  3. ^ National Geophysical Data Center / World Data Service (NGDC/WDS) (1972), Significant Earthquake Database (Data Set), National Geophysical Data Center, NOAA, doi:10.7289/V5TD9V7K
  4. ^ Agnew & Sieh 1978, p. 1722
  5. ^ Agnew & Sieh 1978, p. 1723
  6. ^ "Significant Earthquakes and Faults". California Institute of Technology. Retrieved March 6, 2018.
  7. ^ Bürgmann, R.; Hilley G., Ferretti A. & Novali F. (2006). "Resolving vertical tectonics in the San Francisco Bay Area from permanent scatterer InSAR and GPS analysis" (PDF). Geology. 34 (3): 221–224. Bibcode:2006Geo....34..221B. doi:10.1130/G22064.1.
  8. ^ Wills, C. J.; Weldon II R. J. & Bryant W. A. (2008). "Appendix A: California Fault Parameters for the National Seismic Hazard Maps and Working Group on California Earthquake Probabilities 2007" (PDF). Open File Report 2007-1437. United States Geological Survey. pp. 5–19.
  9. ^ Scharer, K. M.; Biasi G. P., Weldon II R. J. & Fumal T. E. (2010). "Quasi-periodic recurrence of large earthquakes on the southern San Andreas fault". Geology. 38 (6): 555–558. Bibcode:2010Geo....38..555S. doi:10.1130/G30746.1.
  10. ^ Rong-Gong Lin II (October 8, 2010). "San Andreas fault capable of magnitude 8.1 earthquake over 340-mile swath of California, researchers say". Los Angeles Times. Retrieved April 1, 2012.
  11. ^ Zielke, O.; Arrowsmith, J. R.; Grant, L.; Akciz, S. O. (2012), "Slip in the 1857 and Earlier Large Earthquakes Along the Carrizo Plain, San Andreas Fault", Science, 327 (5969): 1119–1122, doi:10.1126/science.1182781] (inactive 2019-03-14), PMID 20093436
  12. ^ Zielke, O.; Arrowsmith, J. R.; Grant, L.; Akciz, S. O. (2012), "High‐Resolution Topography‐Derived Offsets along the 1857 Fort Tejon Earthquake Rupture Trace, San Andreas Fault", Bulletin of the Seismological Society of America, 102 (3): 1135–1154, doi:10.1785/0120110230
  13. ^ a b Sieh 1978a, p. 1424
  14. ^ Sibson R.H. (2003). "Thickness of the Seismic Slip Zone" (PDF). Bulletin of the Seismological Society of America. 93 (3): 1169–1178. Bibcode:2003BuSSA..93.1169S. doi:10.1785/0120020061.
  15. ^ Sieh 1978b, p. 1731
  16. ^ a b "Fort Tejon Earthquake". Southern California Earthquake Center. Archived from the original on October 18, 2013. Retrieved March 25, 2012.
  17. ^ a b Sieh 1978b, p. 1733
  18. ^ Sieh 1978b, pp. 1731–1735
  19. ^ Sieh 1978b, pp. 1735–1737
  20. ^ a b Sieh 1978b, p. 1737
  21. ^ Kerr, R. A. (September 28, 2004), "The Parkfield Earthquake, Finally", Science, American Association for the Advancement of Science
  22. ^ Sieh 1978b, pp. 1737, 1739, 1741–42
  23. ^ Sieh 1978b, p. 1742
  24. ^ Agnew & Sieh 1978, pp. 1721–1723
  25. ^ Kimbro, Edna E. "Construction Chronology of the Site of Holy Cross Church: Ex-Mission Santa Cruz became Holy Cross". Santa Cruz Public Libraries. Retrieved December 16, 2012.
  26. ^ a b Meltzner & Wald 1999, pp. 1117
  27. ^ Sieh 1978a, p. 1421
  28. ^ Bernstein, Sharon (January 10, 2007). "Past offers lessons on future Big One – Scientists begin a study of quake readiness by raising awareness of a massive temblor in 1857". Los Angeles Times. Retrieved March 28, 2012.


External links

1857 earthquake

1857 earthquake may refer to:

1857 Basilicata earthquake (Italy)

1857 Fort Tejon earthquake (California, US)

1857 Parkfield earthquake, see collective article Parkfield earthquake (California, US)

Casa de la Guerra

The Casa de la Guerra was the residence of the fifth commandant of the Presidio de Santa Barbara, José de la Guerra y Noriega from 1828 until his death in 1858. Descendants of José lived in the home until 1943. The site is currently owned and operated by the Santa Barbara Trust for Historic Preservation as a historic house museum. The address is 15 East De la Guerra Street, Santa Barbara, California.

The time when José lived in the casa it was known to locals as the casa grande (big house), as the thirteen room structure dwarfed the surrounding one room adobes. In the casa grande period, José added the altito structure. The altito structure no longer stands, but acted as José's office and was where he stored his money.

The 1857 Fort Tejon earthquake did significant damage to the residence, and due to José's declining health, his son Pablo spearheaded renovations. Pablo's renovations reflected the change in style in the Santa Barbara area, modifying the home to give it a Victorian appearance. The most significant changes in this time were the removal of the adobe columns in favor of wooden columns and the addition of wooden siding to the house.

The Casa is a Santa Barbara City Landmark, a California Historical Landmark. It is listed on the National Register of Historic Places together with Paseo de la Guerra as "El Paseo and Casa de la Guerra".

The house is being restored and furnished to appear as it might have between 1828 and 1858. The Casa de la Guerra interior is open to visitors Saturdays and Sundays, although the exterior may be explored any time.

Fort Tejon

Fort Tejon in California is a former United States Army outpost which was intermittently active from June 24, 1854, until September 11, 1864. It is located in the Grapevine Canyon (La Cañada de las Uvas) between the San Emigdio Mountains and Tehachapi Mountains. It is in the area of Tejon Pass along Interstate 5 in Kern County, California, the main route through the mountain ranges separating the Central Valley from the Los Angeles Basin and Southern California. The fort's location protected the San Joaquin Valley from the south and west.

Frazier Mountain

Frazier Mountain is a broad, pine-forested peak in the Transverse Ranges System, within the Los Padres National Forest in northeastern Ventura County, California. At 8,017 feet (2,444 m), Frazier Mnt. is the sixteenth-highest mountain in the Transverse Ranges of Southern California.

Kern River

The Kern River, originally Rio de San Felipe, later La Porciuncula, is a river in the U.S. state of California, approximately 165 miles (270 km) long. It drains an area of the southern Sierra Nevada mountains northeast of Bakersfield. Fed by snowmelt near Mount Whitney, the river passes through scenic canyons in the mountains and is a popular destination for whitewater rafting and kayaking. It is the only major river in the Sierra Nevada mountain range that drains in a southerly direction.

The Kern River formerly emptied into the now dry Buena Vista Lake and Kern Lake via the Kern River Slough, and Kern Lake in turn emptied into Buena Vista Lake via the Connecting Slough at the southern end of the Central Valley. Buena Vista Lake, when overflowing, first backed up into Kern Lake and then upon rising higher drained into Tulare Lake via Buena Vista Slough and a changing series of sloughs of the Kern River. The lakes were part of a partially endorheic basin that sometimes overflowed into the San Joaquin River. This basin also included the Kaweah and Tule Rivers, as well as southern distributaries of the Kings that all flowed into Tulare Lake.

Since the late 19th century the Kern has been almost entirely diverted for irrigation, recharging aquifers and the California Aqueduct, although some water empties into Lake Webb and Lake Evans, two small lakes in a portion of the former Buena Vista Lakebed. The lakes were created in 1973 for recreational use. The lakes hold 6,800 acre⋅ft (8,400 dam3) combined. Crops are grown in the rest of the former lakebed. In extremely wet years the river will reach the Tulare Lake basin through a series of sloughs and flood channels.

Despite its remote source, nearly all of the river is publicly accessible. The Kern River is particularly popular for wilderness hiking and whitewater rafting. The Upper Kern River is paralleled by trails to within a half-mile of its source (which lies at 13,600 feet (4,100 m)). Even with the presence of Lake Isabella, the river is perennial down to the lower Tulare Basin. Its swift flow at low elevation makes the river below the reservoir an extremely popular location for rafting.

Lake of the Woods, California

Lake of the Woods is an unincorporated area and census-designated place (CDP) in southwestern Kern County, California. As of the 2010 census the population was 917.The community is in Cuddy Canyon in the San Emigdio Mountains, along the Ventura and Kern County line. It is within the Los Padres National Forest.

The name "Lake of the Woods" was bestowed by pioneer Mrs. Florence Cuddy, when the community was established in 1925. The reservoir for which it was named has been dry since 1962, when its dam burst.

Lebec, California

Lebec is an unincorporated area and census-designated place in southwestern Kern County, California. As of the 2010 census, the population was 1,468.

List of earthquakes in the United States

The following is a list of notable earthquakes and/or tsunamis which had their epicenter in areas that are now part of the United States with the latter affecting areas of the United States. Those in italics were not part of the United States when the event occurred.

Earthquake swarms which affected the United States:

1962–71 Denver earthquake swarm

Enola earthquake swarm

2008 Reno earthquakes

Guy-Greenbrier earthquake swarm

2009–present Oklahoma earthquake swarmsEarthquakes which affected the United States but whose epicenters were outside the United States borders:

1925 Charlevoix–Kamouraska earthquake – magnitude 6.2 earthquake, no injuries or fatalities anywhere

2010 Baja California earthquake (Mexico near S California) – magnitude 7.2 earthquake, 4 fatalities and 100 injuries, none in the United StatesEarthquakes which did not affect the United States directly, but caused tsunamis which did:

1960 Valdivia earthquake and tsunami – magnitude 9.5 earthquake, between 2200–6000 fatalities, including 61 in Hilo, HI

2006 Kuril Islands earthquake and tsunami – magnitude 8.3 earthquake, no injuries or fatalities anywhere

2009 Samoa earthquake and tsunami – magnitude 8.0 earthquake with an epicenter 120 miles (190 km) southwest of American Samoa generated tsunami waves up to 16 feet (5 m), killing 34 people in American Samoa and causing extensive damage

2010 Chile earthquake and tsunami – magnitude 8.8 earthquake, ~525 fatalities and unknown number of injuries, none in the United States

2011 Tohoku earthquake and tsunami – magnitude 9.0 earthquake, 15,850–28,000 fatalities and 6,011 injured, one fatality and unknown number of injuries in the United States

2012 Haida Gwaii earthquake – magnitude 7.8 earthquake with an epicenter on Moresby Island in British Columbia, the second largest Canadian earthquake ever recorded by a seismometer, over 100,000 people were evacuated to higher ground in the state of Hawai'i

Mission San Buenaventura

Mission San Buenaventura is a Spanish mission founded by the Franciscans in present-day Ventura, California. Founded on March 31, 1782, it was the ninth Spanish mission established in California and the last to be established by Father Junípero Serra. The mission was named after Saint Bonaventure, a 13th century Franciscan saint and Doctor of the Church. The mission is located in the historic downtown of Ventura.

Mission San Buenaventura was planned to be founded in 1770, but the founding was delayed because of the low availability of the military escorts needed to establish the mission. In 1793, the first church burned down. Today, only a small section of the entire mission complex still stands; the cemetery to the left of the church is covered by a school. It took the neophytes 16 years to build the new church, which still functions as a parish church of the Archdiocese of Los Angeles.

Mission Santa Cruz

Mission Santa Cruz (La Misión de la Exaltación de la Santa Cruz, which translates as The Mission of the Exaltation of the Holy Cross) was a Spanish mission founded by the Franciscan order in present-day Santa Cruz, California. The mission was founded in 1791 and named for the feast of the Exaltation of the Cross, adopting the name given to a nearby creek by the missionary priest Juan Crespi, who accompanied the explorer Gaspar de Portolá when he camped on the banks of the San Lorenzo River on October 17, 1769.As with the other California missions, Mission Santa Cruz served as a site for ecclesiastical conversion of natives, first the Amah Mutsun people, the original inhabitants of the region renamed the “Ohlone” by the Spaniards, and later the Yokuts from the east. The settlement was the site of the first autopsy in Alta California.The current Holy Cross Church was built on the site of the original mission church in 1889, and it remains an active parish of the Diocese of Monterey. A section of stone foundation wall from one of the mission buildings and a few old headstones from the mission cemetery can be found directly behind the present Holy Cross Church. A reduced-scale "replica" chapel was built near the mission site in the 1930s and functions as a chapel of Holy Cross Church. Today's Plaza Park occupies the same location as the original plaza, at the center of the former mission complex. The complex at one time included as many as 32 buildings. The only surviving mission building, a dormitory for native acolytes, has been restored to its original appearance and functions as a museum of the Santa Cruz Mission State Historic Park.

Neenach, California

Neenach ( NEE-nak) is an agricultural settlement in northwestern Los Angeles County, California, with a population of about 800. It is facing a massive change with the proposed construction of a 23,000-home planned community to its north called Centennial.

Parkfield, California

Parkfield (formerly Russelsville) is an unincorporated community in Monterey County, California. It is located on Little Cholame Creek 21 miles (34 km) east of Bradley, at an elevation of 1,529 feet (466 m). As of 2007 road signs announce the population as 18.

Parkfield is located at 35°53′59″N 120°25′58″W in the Temblor Range between the San Joaquin Valley and the Central Coast, at an elevation of 1,529 feet (466 m) above sea level. Mining and Homesteading used to be a prosperous activity in this community, but the mines were exhausted below economic recovery levels and the industry moved elsewhere. Today, it is a small town of about 18 people, most of whom are ranchers and farmers. There is a small tourism industry in the town based on equine-related events, hunting, a bluegrass music festival, and Parkfield's unique earthquake history (see the geology section below). The Parkfield motto is, "Be here when it happens."

A post office operated at Parkfield from 1884 to 1954. The town's original name of Russelsville was rejected by the post office and Parkfield was chosen from the town's park-like setting among oak trees.The ZIP Code is 93451, and the community is inside area code 805.

Parkfield earthquake

Parkfield earthquake is a name given to various large earthquakes that occurred in the vicinity of the town of Parkfield, California, United States. The San Andreas fault runs through this town, and six successive magnitude 6 earthquakes occurred on the fault at unusually regular intervals, between 12 and 32 years apart (with an average of every 22 years), between 1857 and 1966. The most recent significant earthquake to occur here happened on September 28, 2004.

Earthquakes may occur regularly here because the location is about midway on a fault segment between a locked segment to the south (last major earthquake 1857) and a creeping segment to the north where two tectonic plates are continuously moving without major earthquakes.

Rancho Castac

This is an article about a former California rancho. For a community of a similar name in the same general area, see Castaic, California.

Rancho Castac or Rancho Castec was a 22,178-acre (89.75 km2) Mexican land grant in present-day Kern and Los Angeles counties, California, made by Governor Manuel Micheltorena to Jose Maria Covarrubias in 1843. The rancho in the Tehachapi Mountains lay between Castac Lake on the south and the present Grapevine on the north and included what is now the community of Lebec. The rancho is now a part of the Tejon Ranch.

The word Castac is derived from Kashtiq, the Chumash-language name that the Chumash people gave to the area nearby.

The title to Rancho Castac was granted by Governor Micheltorena in 1843 to schoolteacher and government official José María Covarrubias.

With the cession of California to the United States after the Mexican-American War, the 1848 Treaty of Guadalupe Hidalgo provided that existing land grants would be honored. As required by the Land Act of 1851, a claim for Rancho Castac was filed with the U.S. Public Land Commission in 1853, and the grant was patented to Covarrubias in 1866.In 1860, Samuel A. Bishop purchased the rancho, and in 1864 he settled in Fort Tejon. Bishop sold the land to Robert Symington Baker, who in 1866 resold it to Edward Beale. The latter, who had been the Superintendent of Indian Affairs in California, later acquired three other Mexican and grants — (Rancho Los Alamos y Agua Caliente, Rancho El Tejon and Rancho La Liebre) — to create the present Tejon Ranch.

Santa Gertrudis Asistencia

The Santa Gertrudis Asistencia, also known as the Santa Gertrudis Chapel, was an asistencia ("sub-mission") to the Mission San Buenaventura, part of the system of Spanish missions in Las Californias—Alta California. Built at an unknown date between 1792 and 1809, it was located approximately five miles from the main mission, inland and upstream along the Ventura River. The site was buried in 1968 by the construction of California State Route 33. Prior to the freeway's construction, archaeologists excavated and studied the site. A number of foundation stones were moved and used to create the Santa Gertrudis Asistencia Monument which was designated in 1970 as Ventura County Historic Landmark No. 11.

Tehachapi, California

Tehachapi is a city in Kern County, California, in the Tehachapi Mountains, at an elevation of 3,970 feet (1,210 m) between the San Joaquin Valley and the Mojave Desert.

Tehachapi is 35 miles (56 km) east-southeast of Bakersfield, and 20 miles (32 km) west of Mojave. According to the United States Census Bureau, the city has a total area of 10.0 square miles (26 km2) and a population of 14,414.

Tehachapi Mountains

The Tehachapi Mountains are a mountain range in the Transverse Ranges system of California in the Western United States. The range extends for approximately 40 miles (64 km) in southern Kern County and northwestern Los Angeles County.

Wheeler Ridge, California

Wheeler Ridge is an unincorporated community in the southwestern San Joaquin Valley, within Kern County, California. It is at the junction of the valley floor and the Wheeler Ridge landform of the Tehachapi Mountains.

White Wolf Fault

The White Wolf Fault is a fault in southern California, located along the northwestern transition of the Tejon Hills and Tehachapi Mountains with the San Joaquin Valley. It is north of the intersection of the San Andreas Fault and the Garlock Fault, and roughly parallel with the latter. It is classed as a reverse (vertical motion) fault with a left lateral (sinistral) component.

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