List of earthquakes in California

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Probabilistic seismic hazard map

Although the written history of California is not long, records of earthquakes exist that affected the Spanish missions that were constructed beginning in the late 18th century, those records ceased when the missions were secularized in 1834, and from that point until the California Gold Rush in the 1840s, records were sparse. Other sources for the occurrence of earthquakes usually came from ship captains and other explorers, for the period 1850–2004, there was about one potentially damaging event per year on average, though many of these did not cause loss of life or property damage. The earliest known earthquake was documented in 1769 by the Spanish explorers and Catholic missionaries of the Portolá expedition as they traveled northward from San Diego along the Santa Ana River near the present site of Los Angeles.[1][2]

The few damaging earthquakes that occurred in the American Midwest and the East Coast were well known (1755 Cape Ann, 1811–12 New Madrid, 1886 Charleston), and it became apparent to settlers that the earthquake hazard situation was much different in the West. While the 1812 Wrightwood, 1857 Fort Tejon, and 1872 Lone Pine shocks were only moderately destructive in mostly unpopulated areas, the 1868 Hayward event affected the thriving financial hub that is the San Francisco Bay Area, with damage from Santa Rosa in the north to Santa Cruz in the south. By this time, scientists were well aware of the threat, but seismology was still in its infancy. Reactions following destructive events in the late 19th and early 20th centuries included developers, press, and boosters minimizing and downplaying the risk out of fear that the ongoing economic boom would be negatively affected.[3][4]

California earthquakes (1769–2000)

According to seismologist Charles Richter, the 1906 San Francisco earthquake moved the United States Government into acknowledging the problem. Prior to that, no agency was specifically focused on researching earthquake activity, the United States Weather Bureau did record when they happened and several United States Geological Survey scientists had briefly disengaged from their regular duties of mapping mineral resources to write reports on the New Madrid and Charleston events, but no trained geologists were working on the problem until the Coast and Geodetic Survey was made responsible after 1906. The outlook improved when professor Andrew Lawson brought the state's first monitoring program online at the University of California, Berkeley in 1910 with seismologist Harry Wood, who was later instrumental in getting the Caltech Seismological Laboratory operational in the 1920s.[3][5]

Early developments at the Caltech lab in Pasadena included an earthquake observation network using their own custom built short period seismometers, the Richter magnitude scale, and an updated version of the Mercalli intensity scale. In 1933, the Long Beach earthquake occurred in a populated area and damaged or destroyed a large number of public school buildings in Long Beach and Los Angeles, some decades later, the 1971 San Fernando earthquake affected the San Fernando Valley north of Los Angeles. In both cases, the perception of those involved with policy making in California was changed, and state laws and building codes were modified (but not without much debate) to require commercial and residential properties to be built to withstand earthquakes. Higher standards were established for fire stations, hospitals, and schools and construction of dwellings was also restricted near known active faults.[4][5]

Tectonic setting[edit]

During the last 66 million years, nearly the entire west coast of North America was dominated by a subduction zone, with the Farallon Plate subducting beneath the North American Plate. Presently, the Juan de Fuca Plate (with its Explorer and Gorda satellite plates) and the Rivera and Cocos Plates are the only remnants of the once much larger Farallon Plate. The plate margin that remains in California is that of the strike-slip San Andreas Fault (SAF), the diffuse Pacific–North American plate boundary that extends east into the Basin and Range Province of eastern California and western Nevada (a seismically active area called Walker Lane) and southwest into the California Continental Borderland region off the central and southern coasts. This system of faults terminates in the north at the Mendocino Triple Junction, one of the most seismically active regions in the state, where earthquakes are occasionally the result of intraplate deformation within the Gorda Plate. It terminates in the south at the Salton Sea where displacement transitions to a series of spreading centers and transform faults, beginning with the Brawley Seismic Zone in the Imperial Valley.[6]

In the San Francisco Bay Area, the San Andreas system of faults spans offshore and into the East Bay area, with the bulk of the faults lying to the east of the main SAF. There is a 70% probability that one of these faults will generate a M6.7 or greater earthquake before 2030, including the Hayward Fault Zone, which has gone beyond its average return period of 130 years. While the SAF north of San Francisco is quiet, the central SAF segment near San Juan Bautista is where fault creep was first studied, and to the south is where the recurring Parkfield earthquakes occur. The secondary faults lie to the west of the main SAF at the extreme southern portion, including the active and young San Jacinto Fault Zone, which may be taking over as the primary boundary south of Cajon Pass. A paleoseismic investigation using Lidar revealed that more than 5 meters (16 ft) of slip has accumulated since the 1857 event on the southern SAF, which borders the Mojave Desert to the north and east of the Greater Los Angeles Area. Near the Transverse Ranges, reverse and thrust faults have produced damaging earthquakes in Santa Barbara and the San Fernando Valley.[6]

Earthquakes[edit]

Date Area M MMI Deaths Injuries Total damage / notes
2014-08-24 North Bay 6.0 Mw VIII 1 ~200 $362 million–$1 billion
2014-03-28 Los Angeles Area 5.1 Mw VI Few $10.8 million [7]
2010-04-04 Baja California 7.2 Mw VII 2–4 100–233 $1.15 billion
2010-01-09 North Coast 6.5 Mw VI 35 $21.8–43 million
2008-07-29 Los Angeles Area 5.5 Mw VI 8 Limited
2007-10-30 South Bay 5.6 Mw VI Minor
2003-12-22 Central Coast 6.6 Mw VIII 2 40 $250–300 million
2000-09-03 North Bay 5.0 Mw VII 41 $10–50 million
1999-10-16 Eastern 7.1 Mw VII 4–5 Limited
1994-12-26 North Coast 5.5 Mw VII $2.1–5 million [7]
1994-01-17 Los Angeles Area 6.7 Mw IX 57 8,700+ $13–$40 billion
1992-06-28 Inland Empire 6.5 Mw VIII Some Moderate / triggered
1992-06-28 Inland Empire 7.3 Mw IX 3 400+ $92 million
1992-04-26 North Coast 6.6 Mw VIII Damage / triggered
1992-04-26 North Coast 6.5 Mw VIII Damage / triggered
1992-04-25 North Coast 7.2 Mw IX 98–356 $48.3–75 million / tsunami
1992-04-22 Inland Empire 6.3 Ms VII 32 Light–moderate [7]
1991-08-17 North Coast 6.2 Ms VII Slight damage / landslides [7]
1991-06-28 Los Angeles Area 5.6 Mw VII 1 100–107 $33.5–40 million
1990-02-28 Los Angeles Area 5.7 Mw VII 30 $12.7 million
1989-10-17 Santa Cruz Mountains 6.9 Mw IX 63 3,757 $5.6–6 billion / tsunami
1989-08-08 Santa Cruz Mountains 5.4 ML VII 1 Minor
1987-11-24 Imperial Valley 6.5 Mw VII Triggered [8]
1987-11-23 Imperial Valley 6.1 Mw VI $3 million [8]
1987-10-01 Los Angeles Area 5.9 Mw VIII 8 200 $213–358 million
1986-07-21 Eastern 6.2 Mw VI 2 $2.7 million / sequence
1986-07-13 South Coast 5.8 Mw VI 1 $700,000 [9]
1986-07-08 Inland Empire 6.0 Mw VII 29–40 $4.5–6 million
1984-04-24 South Bay 6.2 Mw VIII 21–27 $7.5–8 million
1986-03-31 South Bay 5.6 Mw VI 6 Minor [10]
1983-05-02 Central Valley 6.2 Mw VIII 94 $10 million
1981-04-26 Imperial Valley 5.9 Mw VII $1–3 million [11]
1980-11-08 North Coast 7.3 Mw VII 6 $2–2.75 million
1980-05-25 Eastern 6.2 Mw VII 9 $1.5 million / swarm [12]
1980-01-26 East Bay 5.4 Mw VII Doublet [13]
1980-01-24 East Bay 5.8 Mw VII $11.5 million / doublet [14]
1979-10-15 Imperial Valley 6.4 Mw IX 91 $30 million
1979-08-06 South Bay 5.7 Mw VII 16 $500,000
1978-08-13 Central Coast 5.8 Mw VII 65 $12 million [15]
1975-08-01 Butte County 5.7 ML VIII 10 $3 million [7]
1973-02-21 South Coast 5.8 Mw VII Several $1 million
1971-02-09 Los Angeles Area 6.5–6.7 Mw XI 58–65 200–2,000 $505–553 million
1969-10-01 North Bay 5.7 Mw VIII Doublet
1969-10-01 North Bay 5.6 Mw VII 1 $8.35 million / doublet
1968-04-08 Imperial Valley 6.5 Mw VII Damage / rockslides [16]
1957-03-22 Bay Area 5.7 Mw VII 1 40 $1 million
1954-12-21 North Coast 6.5 ML VII 1 Several $2.1 million [17]
1952-08-22 Central Valley 5.8 Mw VIII 2 Several $10 million
1952-07-21 Central Valley 7.3 Mw XI 12 Hundreds $60 million
1948-12-04 Inland Empire 6.3 ML VII Several Minor
1941-11-14 Los Angeles Area 5.4 Ms VIII $1.1 million [18]
1941-06-30 Central Coast 5.9 Mw VIII $100,000 [19]
1940-05-18 Imperial Valley 6.9 Mw X 9 20 $6 million
1933-03-10 South Coast 6.4 Mw VIII 115–120 $40 million
1932-06-06 North Coast 6.4 Mw VIII 1 3 Severe
1927-11-04 Central Coast 7.3 Mw VIII Moderate / tsunami [20]
1925-06-29 Central Coast 6.8 Mw IX 13 $8 million
1923-01-22 North Coast 7.2 Ms VIII Severe / tsunami [21]
1920-06-21 Los Angeles Area 4.9 ML VIII More than $100,000 [22]
1918-04-21 Inland Empire 6.7 Mw IX 1 Several $200,000
1915-06-22 Imperial Valley 5.5 Mw VIII Additional damage / doublet [23]
1915-06-22 Imperial Valley 5.5 Mw VIII 6 $900,000 / doublet [23]
1906-04-18 Imperial Valley 6.3 Mw VIII Damage / triggered [24][25]
1906-04-18 NorthernCentral 7.8 Mw XI 3000 Conflagration / tsunami
1899-12-25 Inland Empire 6.7 Mw IX 6 $50,000 or more [26]
1898-03-30 North Bay 5.8–6.4 Mw VIII–IX $350,000 / moderate
1892-04-21 Central Valley 6.2 MLa IX Doublet
1892-04-19 North Bay 6.4 MLa IX 1 $225,000–250,000 / doublet
1892-02-23 Baja California 7.1–7.2 Mw VIII Moderate
1873-11-23 North Coast 6.7 MLa VIII Damage / ground cracks [27]
1872-03-26 Eastern 7.4–7.9 Mw X 27 56 $250,000
1868-10-21 Bay Area 6.3–6.7 Mw IX 30 $350,000
1865-10-08 Santa Cruz Mountains 6.3 MLa VIII $500,000 [28]
1857-01-09 CentralSouthern 7.9 Mw IX 2 Severe
1838-06 Bay Area 6.8–7.2 Mw VIII Minor
1812-12-21 Central Coast 7.1 MLa VIII 1 Tsunami [29]
1812-12-08 Inland Empire 6.9 ML VIII 40 Moderate
Stover & Coffman 1993 uses various seismic scales. MLa is a local magnitude that is equivalent to ML (Richter magnitude scale) and is used for events that occurred prior to the instrumental period. It is based on the area of perceptibility (as presented on isoseismal maps). Mw = moment magnitude scale and Ms = surface wave magnitude. The inclusion criteria for adding events are based on WikiProject Earthquakes' notability guideline that was developed for stand alone articles, the principles described are also applicable to lists. In summary, only damaging, injurious, or deadly events should be recorded.

See also[edit]

References[edit]

  1. ^ Toppozada, T. R.; Branum, D. (2004), "California earthquake history", Annals of Geophysics, Istituto Nazionale Geofisica e Vulcanologia, 47 (2–3): 509–512 
  2. ^ Ellsworth, W. L. (1990), "Earthquake history, 1769–1989", The San Andreas Fault System, California – USGS Professional Paper 1515, United States Geological Survey, pp. 156, 157, ISBN 978-0607716269 
  3. ^ a b Hough, S. E. (2007), Richter's Scale: Measure of an Earthquake, Measure of a Man, Princeton University Press, pp. 51–61, ISBN 978-0691128078 
  4. ^ a b Geschwind, C. (2001). California Earthquakes: Science, Risk, and the Politics of Hazard Mitigation. Johns Hopkins University Press. pp. 3–22, 105–114, 165, 181. ISBN 978-0801865961. 
  5. ^ a b Goodstein, J. R. (2006), Millikan's School: A History of the California Institute of Technology, W. W. Norton & Company, pp. 125–152, ISBN 978-0393329988 
  6. ^ a b Yeats, R. (2012), Active Faults of the World, Cambridge University Press, pp. 19, 80–83, 89–94, 96–114, ISBN 978-0521190855 
  7. ^ a b c d e National Geophysical Data Center / World Data Service (NGDC/WDS), Significant Earthquake Database, National Geophysical Data Center, NOAA, doi:10.7289/V5TD9V7K 
  8. ^ a b Stover & Coffman 1993, pp. 98, 179, 180
  9. ^ Stover & Coffman 1993, pp. 97, 177
  10. ^ Stover & Coffman 1993, pp. 97, 176, 177
  11. ^ Stover & Coffman 1993, pp. 96, 168, 169
  12. ^ Stover & Coffman 1993, pp. 95, 168
  13. ^ Stover & Coffman 1993, pp. 95, 166, 167
  14. ^ Stover & Coffman 1993, pp. 94, 166, 167
  15. ^ Stover & Coffman 1993, pp. 94, 163
  16. ^ Stover & Coffman 1993, pp. 91, 154
  17. ^ Stover & Coffman 1993, pp. 88, 148
  18. ^ Stover & Coffman 1993, pp. 82, 137
  19. ^ Stover & Coffman 1993, pp. 82, 136
  20. ^ Stover & Coffman 1993, pp. 77, 128
  21. ^ Stover & Coffman 1993, pp. 77, 125
  22. ^ Stover & Coffman 1993, pp. 76, 124
  23. ^ a b Stover & Coffman 1993, pp. 76, 121
  24. ^ Stover & Coffman 1993, pp. 75, 105
  25. ^ Meltzner, A. J.; Wald, D. J. (2003), "Aftershocks and Triggered Events of the Great 1906 California Earthquake", Bulletin of the Seismological Society of America, Seismological Society of America, 93 (5): 2,160, 2,164, 2,166, 2,169, 2,170, doi:10.1785/0120020033 
  26. ^ Stover & Coffman 1993, pp. 74, 113
  27. ^ Stover & Coffman 1993, pp. 73, 108
  28. ^ Stover & Coffman 1993, pp. 73, 104
  29. ^ Stover & Coffman 1993, pp. 72, 100

Sources

External links[edit]