List of earthquakes in California

Probabilistic seismic hazard map

The earliest known earthquake in the U.S. state of California 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. Ship captains and other explorers also documented earthquakes. As Spanish missions were constructed beginning in the late 18th century, earthquakes records were kept. After the missions were secularized in 1834, records were sparse until the California Gold Rush in the 1840s. From 1850–2004, there was about one potentially damaging event per year on average, though many of these did not cause serious consequences or loss of life.[1][2]

Since the three damaging earthquakes that occurred in the American Midwest and the United States East Coast (1755 Cape Ann, 1811–12 New Madrid, 1886 Charleston) were well known, it became apparent to settlers that the earthquake hazard was different in California. While the 1812 San Juan Capistrano, 1857 Fort Tejon, and 1872 Owens Valley shocks were in mostly unpopulated areas and only moderately destructive, the 1868 Hayward event affected the thriving financial hub of 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. Following destructive earthquakes in the late 19th and early 20th centuries, real estate developers, press, and boosters minimized and downplayed the risk of earthquakes 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 after 1906 when the United States Coast and Geodetic Survey was made responsible. 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 in Pasadena operational in the 1920s.[3][5]

Early developments at the Caltech lab included an earthquake observation network using their own custom-built short-period seismometers, the Richter magnitude scale, and the Modified Mercalli intensity scale (an updated version of the Mercalli intensity scale). In 1933, the Long Beach earthquake occurred in a populated area and damaged or destroyed many public school buildings in Long Beach and Los Angeles. Some decades later, the San Fernando earthquake affected the San Fernando Valley north of Los Angeles with heavy damage to several hospitals. In both cases, the perception of California policy makers changed, and state laws and building codes were modified (with 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 active faults.[4][5]

## Tectonic setting[edit]

See also: Los Angeles Basin, Mendocino Fracture Zone, and Salton Trough

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 6.7 Mw or greater earthquake before 2030, including the Hayward Fault Zone, which has gone beyond its average return period of 130 years (155 years ago as of January 2024)[7]. While the SAF is quiet north of San Francisco , the central SAF segment near San Juan Bautista is where aseismic creep was first studied, and to the south is where the recurring Parkfield earthquakes occur. The secondary faults lay 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 16 feet (5 m) 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]

## Notable earthquakes[edit]

Date  | Name  | Area  | Mag. | MMI | Deaths  | Injuries  | Total damage  | Notes

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2022-12-20 | Humboldt County  | North Coast | 6.4 Mw |  VIII  | 2  | 17  |  |
2019-07-05 | Ridgecrest  | Eastern | 7.1 Mw |  IX  |  | 5  | $5.3bn  | Doublet
2019-07-04 | Ridgecrest  | Eastern | 6.4 Mw |  VIII  | 1  | 20  | $5.3bn  | Doublet
2014-08-24 | South Napa  | North Bay | 6.0 Mw |  VIII  | 1  | ~200  | $362M–$1bn  |
2014-03-28 | La Habra  | LA Area | 5.1 Mw |  VII  |  | Few  | $10.8M  | [8]
2010-04-04 | Baja California  | Baja California | 7.2 Mw |  VII  | 2–4  | 100–233  | $1.15bn  |
2010-01-09 | Eureka  | North Coast | 6.5 Mw |  VI  |  | 35  | $21.8–43M  |
2008-07-29 | Chino Hills  | LA Area | 5.4 Mw |  VI  |  | 8  | Limited  |
2007-10-30 | Alum Rock  | Bay Area | 5.6 Mw |  VI  |  |  | Limited  |
2003-12-22 | San Simeon  | Central Coast | 6.6 Mw |  VIII  | 2  | 40  | $250–300M  |
2000-09-03 | Yountville  | North Bay | 5.0 Mw |  VII  |  | 41  | $10–50M  |
1999-10-16 | Hector Mine  | Eastern | 7.1 Mw |  VII  |  | 4–5  | Limited  |
1994-01-17 | Northridge  | LA Area | 6.7 Mw |  IX  | 57  | 8,700+  | $13–40bn  |
1992-06-28 | Big Bear  | Inland Empire | 6.5 Mw |  VIII  |  | 63  | More than $60M  | Triggered
1992-06-28 | Landers  | Inland Empire | 7.3 Mw |  IX  | 3  | 400+  | $92M  |
1992-04-26 | Cape Mendocino  | North Coast | 6.6 Mw |  VIII  |  |  | Some  | Triggered
1992-04-26 | Cape Mendocino  | North Coast | 6.5 Mw |  VIII  |  |  | Some  | Triggered
1992-04-25 | Cape Mendocino  | North Coast | 7.2 Mw |  IX  |  | 98–356  | $48–75M  | Tsunami
1992-04-22 | Joshua Tree  | Inland Empire | 6.3 Ms |  VII  |  | 32  | Light–moderate  | [8]
1991-06-28 | Sierra Madre  | LA Area | 5.6 Mw |  VII  | 2  | 100–107  | $34–40M  |
1990-02-28 | Upland  | LA Area | 5.7 Mw |  VII  |  | 30  | $12.7M  |
1989-10-17 | Loma Prieta  | Santa Cruz Mts | 6.9 Mw |  IX  | 63  | 3,757  | $5.6–6bn  | Tsunami
1989-08-08 | Loma Prieta  | Santa Cruz Mts | 5.4 ML |  VII  | 1  |  | Minor  |
1987-11-24 | Elmore Ranch  | Imperial Valley | 6.5 Mw |  VIII  | 2  | 90+  |  | Triggered [9]
1987-11-23 | Superstition Hills  | Imperial Valley | 6.1 Mw |  VIII  |  |  | $3M  | [9]
1987-10-01 | Whittier  | LA Area | 5.9 Mw |  VIII  | 8  | 200  | $213–358M  |
1986-07-21 | Chalfant Valley  | Eastern | 6.2 Mw |  VI  |  | 2  | $2.7M  | Sequence
1986-07-13  | Oceanside  | South Coast | 5.8 Mw |  VI  |  | 1  | $700k  | [10]
1986-07-08 | N. Palm Springs  | Inland Empire | 6.0 Mw |  VII  |  | 29–40  | $4.5–6M  |
1984-04-24 | Morgan Hill  | South Bay | 6.2 Mw |  VIII  |  | 21–27  | $7.5–8M  |
1983-05-02 | Coalinga  | Central Valley | 6.2 Mw |  VIII  |  | 94  | $10M  |
1981-04-26 | Westmorland  | Imperial Valley | 5.9 Mw |  VII  |  |  | $1–3M  | [11]
1980-11-08 | Eureka  | North Coast | 7.3 Mw |  VII  |  | 6  | $2–2.75M  |
1980-05-25  | Mammoth Lakes  | Eastern | 6.2 Mw |  VII  |  | 9  | $1.5M  | Swarm[12]
1980-01-26 | Livermore  | East Bay | 5.4 Mw |  VII  |  |  |  | Doublet [13]
1980-01-24 | Livermore  | East Bay | 5.8 Mw |  VII  |  |  | $11.5M  | Doublet [14]
1979-10-15 | Imperial Valley  | Imperial Valley | 6.4 Mw |  IX  |  | 91  | $30M  |
1979-08-06 | Coyote Lake  | South Bay | 5.7 Mw |  VII  |  | 16  | $500k  |
1978-08-13 | Santa Barbara  | Central Coast | 5.8 Mw |  VII  |  | 65  | $12M  | [15]
1975-08-01  | Butte County  | Butte County | 5.7 ML |  VIII  |  | 10  | $3M  | [8]
1973-02-21 | Point Mugu  | South Coast | 5.8 Mw |  VII  |  | Several  | $1M  |
1971-02-09 | San Fernando  | LA Area | 6.6 Mw |  XI  | 58–65  | 200–2,000  | $505–553M  |
1969-10-01 | Santa Rosa  | North Bay | 5.7 Mw |  VIII  |  |  |  | Doublet
1969-10-01 | Santa Rosa  | North Bay | 5.6 Mw |  VII  | 1  |  | $8.35M  | Doublet
1968-04-08 | Borrego Mtn  | Imperial Valley | 6.5 Mw |  VII  |  |  | Some  | Rockslides [16]
1957-03-22 | San Francisco  | Bay Area | 5.7 Mw |  VII  | 1  | 40  | $1M  |
1954-12-21  | Eureka  | North Coast | 6.5 ML |  VII  | 1  | Several  | $2.1M  | [17]
1952-08-22 | Kern County  | Central Valley | 5.8 Mw |  VIII  | 2  | Several  | $10M  |
1952-07-21 | Kern County  | Central Valley | 7.3 Mw |  XI  | 12  | Hundreds  | $60M  |
1948-12-04 | Desert Hot Springs  | Inland Empire | 6.4 Mw |  VII  |  | Several  | Minor  |
1941-11-14  | Torrance–Gardena  | LA Area | 5.4 Ms |  VIII  |  |  | $1.1M  | [18]
1941-06-30  | Santa Barbara  | Central Coast | 5.9 Mw |  VIII  |  |  | $100k  | [19]
1940-05-18 | El Centro  | Imperial Valley | 6.9 Mw |  X  | 9  | 20  | $6M  |
1933-03-10 | Long Beach  | South Coast | 6.4 Mw |  VIII  | 115–120  |  | $40M  |
1932-06-06 | Eureka  | North Coast | 6.4 Mw |  VIII  | 1  | 3  | Severe  |
1927-11-04 | Lompoc  | Central Coast | 7.3 Mw |  |  |  | Moderate  | Tsunami [20]
1925-06-29 | Santa Barbara  | Central Coast | 6.8 Mw |  IX  | 13  |  | $8M  |
1923-01-22  | Humboldt County  | North Coast | 7.2 Ms |  |  |  | Severe  | Tsunami [21]
1920-06-21  | Inglewood  | LA Area | 4.9 ML |  VIII  |  |  | More than $100k  | [22]
1918-04-21 | San Jacinto  | Inland Empire | 6.7 Mw |  IX  | 1  | Several  | $200k  |
1915-06-22 | Imperial Valley  | Imperial Valley | 5.5 Mw |  VIII  | 6  |  | $900k  | Doublet [23]
1906-04-18 | San Francisco  | Northern–Central | 7.9 Mw |  XI  | 700–3,000+  |  |  | Conflagration / tsunami
1899-12-25 | San Jacinto  | Inland Empire | 6.7 Mw |  IX  | 6  |  | $50k or more  | [24]
1898-03-30 | Mare Island  | North Bay | 5.8–6.4 Mw |  VIII–IX  |  |  | $350k  |
1892-04-21 | Vacaville–Winters  | Central Valley | 6.2 MLa |  IX  |  |  |  | Doublet
1892-04-19 | Vacaville–Winters  | North Bay | 6.4 MLa |  IX  | 1  |  | $225–250k  | Doublet
1892-02-23 | Laguna Salada  | Baja California | 7.1–7.2 Mw |  VIII  |  |  | Moderate  |
1873-11-23  | Crescent City  | North Coast | 6.7 MLa |  VIII  |  |  | Some  | Ground cracks [25]
1872-03-26 | Owens Valley  | Eastern | 7.4–7.9 Mw |  X  | 27  | 56  | $250k  |
1868-10-21 | Hayward  | Bay Area | 6.3–6.7 Mw |  IX  | 30  |  | $350k  |
1865-10-08  | Santa Cruz Mts  | Santa Cruz Mts | 6.3 MLa |  VIII  |  |  | $500k  | [26]
1857-01-09 | Fort Tejon  | Central–Southern | 7.9 Mw |  IX  | 2  |  | Severe  |
1838-06-?? | San Andreas  | Bay Area | 6.8–7.2 Mw |  VIII  |  |  | Minor  |
1812-12-21 | Ventura  | Central Coast | 7.1 MLa |  VIII  | 1  |  |  | Tsunami [27]
1812-12-08 | San Juan Capistrano  | South Coast | 6.9–7.5  |  VII–IX  | 40  |  | Moderate  |
Stover & Coffman 1993 uses various seismic scales. M`la` 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 essay 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.
k= thousand, M = million, bn = billion

## See also[edit]

* Alquist Priolo Special Studies Zone Act
* California earthquake forecast
* Field Act
* Geography of California
* Geology and geological history of California
* Southern California Earthquake Center
* Timeline of the Portolá expedition

## References[edit]

1. ^ Toppozada, T. R.; Branum, D. (2004), "California earthquake history", Annals of Geophysics, 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", Physics Today, Princeton University Press, 61 (1): 51–61, Bibcode:2008PhT....61a..60H, doi:10.1063/1.2835157, 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. ^ "Magnitude 4.2 earthquake strikes Southern California". 2024-01-25. Retrieved 2024-01-25.
8. ^ a b c National Geophysical Data Center / World Data Service (NGDC/WDS) (1972), Significant Earthquake Database (Data Set), National Geophysical Data Center, NOAA, doi:10.7289/V5TD9V7K
9. ^ a b Stover & Coffman 1993, pp. 98, 179, 180
10. ^ Stover & Coffman 1993, pp. 97, 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. ^ Stover & Coffman 1993, pp. 76, 121
24. ^ Stover & Coffman 1993, pp. 74, 113
25. ^ Stover & Coffman 1993, pp. 73, 108
26. ^ Stover & Coffman 1993, pp. 73, 104
27. ^ Stover & Coffman 1993, pp. 72, 100

Sources

* 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

## Further reading[edit]

* Rodda, P. U.; Leviton, A. E. (1983), "Nineteenth Century Earthquake Investigations in California", Earth Sciences History, 2 (1): 48–56, Bibcode:1983ESHis...2...48R, doi:10.17704/eshi.2.1.576065779g862057, JSTOR 24135726
* Wood, H. O. (1916), "The earthquake problem in the western United States", Bulletin of the Seismological Society of America, 6 (4): 197–217, Bibcode:1916BuSSA...6..197W, doi:10.1785/BSSA0060040197, S2CID 130712233

## External links[edit]

Wikimedia Commons has media related to Earthquakes in California.

Look up earthquake in Wiktionary, the free dictionary.

* Information by Region-California – USGS
* Southern California Earthquake Data Center
* Putting Down Roots in Earthquake Country – Earthquake Country Alliance
* Broadband Seismic Data Collection Center – University of California, San Diego
* What Will Happen After The 'Big One' Hits SoCal? – KCET
* Little-known quake, tsunami hazards lurk offshore of Southern California – American Geophysical Union
* California’s other drought: A major earthquake is overdue – The Conversation
* New California bill aims to create a public inventory of collapse-risk buildings – Temblor, Inc.

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Earthquakes in California

Very Large
(7.0–7.9)|

* 1812 San Juan Capistrano (6.9–7.5)
* 1812 Ventura (7.1–7.5)
* 1838 San Andreas (6.8–7.2)
* 1857 Fort Tejon (7.9)
* 1872 Owens Valley (7.4–7.9)
* 1892 Laguna Salada (7.1–7.2)
* 1906 San Francisco (7.8)
* 1915 Baja California (7.0)
* 1927 Lompoc (7.3)
* 1952 Kern County (7.3)
* 1980 Eureka (7.3)
* 1992 Cape Mendocino (7.2)
* 1992 Landers (7.3)
* 1999 Hector Mine (7.1)
* 2010 Baja California (7.2)
* 2019 Ridgecrest (7.1)

Large
(6.0–6.9)|

* 1868 Hayward (6.3–6.7)
* 1892 Vacaville–Winters (6.4, 6.2)
* 1898 Mare Island (5.8–6.4)
* 1899 San Jacinto (6.7)
* 1915 Imperial Valley (6.3 & 6.3)
* 1918 San Jacinto (6.7)
* 1925 Santa Barbara (6.8)
* 1932 Eureka (6.4)
* 1933 Long Beach (6.4)
* 1940 El Centro (6.9)
* 1948 Desert Hot Springs (6.4)
* 1968 Borrego Mountain (6.6)
* 1971 San Fernando (6.5–6.7)
* 1979 Imperial Valley (6.4)
* 1983 Coalinga (6.2)
* 1984 Morgan Hill (6.2)
* 1986 North Palm Springs (6.0)
* 1986 Chalfant Valley (6.2)
* 1987 Superstition Hills (6.2, 6.6)
* 1989 Loma Prieta (6.9)
* 1992 Joshua Tree (6.2)
* 1992 Big Bear (6.5)
* 1994 Northridge (6.7)
* 2003 San Simeon (6.6)
* 2010 Eureka (6.5)
* 2014 South Napa (6.0)
* 2019 Ridgecrest (6.4)
* 2022 Ferndale (6.4)

Moderate
(5.0–5.9)|

* 1957 San Francisco (5.7)
* 1969 Santa Rosa (5.6, 5.7)
* 1973 Point Mugu (5.8)
* 1979 Coyote Lake (5.7)
* 1980 Livermore (5.8)
* 1981 Westmorland (5.9)
* 1987 Whittier Narrows (5.9)
* 1990 Upland (5.7)
* 1991 Sierra Madre (5.6)
* 2000 Yountville (5.0)
* 2007 Alum Rock (5.6)
* 2008 Chino Hills (5.4)
* 2014 La Habra (5.1)

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