1812 Ventura earthquake

Last updated
1812 Ventura earthquake
Ruins of Mission La Purisima Concepcion, ca.1885-1904 (CHS-1803).jpg
Relief map of California.png
Green pog.svg
San Buenaventura
Green pog.svg
San Gabriel
Green pog.svg
San Juan Capistrano
Green pog.svg
San Diego
Bullseye1.png
USGS-ANSS ComCat
Local dateDecember 21, 1812
Local time11:00 PST (UTC-07:00)
Magnitude Mw 7.1
Epicenter Santa Barbara Channel or Wrightwood
34°12′N119°54′W / 34.2°N 119.9°W / 34.2; -119.9
Areas affected Alta California, New Spain Present day Santa Barbara and Ventura County
Max. intensity MMI X (Extreme) [1]
Tsunami3.4 m (11 ft)
ForeshocksYes
AftershocksYes
Casualties2 dead

The 1812 Ventura earthquake (also known as the Santa Barbara earthquake) occurred on the morning of December 21 at 11:00 Pacific Standard Time (PST). The Mw 7.1 earthquake, with a Modified Mercalli intensity scale rating of X (Extreme), along with its resulting tsunami, caused considerable damage to present-day Santa Barbara and Ventura County, California, which was at the time a territory of the Spanish Empire. [2] [3] One person was killed as a result of the earthquake while another from the aftershock. The earthquake occurred just as the region was recovering from another event on December 8. Both events are thought to have been related.

Contents

Geological setting

The San Andreas is the "master fault" of California, it is the main plate boundary in the San Andreas Fault System, consisting of other major active faults. This zone of interaction between the Pacific and North American Plates have resulted in hundreds of faults crisscrossing California. There are several strike-slip, reverse and thrust faults hidden under the Santa Barbara Channel that could produce devastating earthquakes and tsunamis, including a thrust fault that runs along the base of the Santa Monica Mountains. [4] These faults are a result of the "Big Bend" in the San Andreas Fault when it meets with the Garlock Fault, exerting compression in the crust, forcing thrust and reverse faults to push crustal blocks upwards.

Earthquake origins

Studies have placed the source of this earthquake on two faults. The location and source have not been agreed on, with some researchers providing the epicenter north of Wrightwood or in the Santa Barbara Channel. Toppozada and others in 1981 proposed a location 10–20 km (6.2–12.4 mi) southwest of the 1925 Santa Barbara earthquake. Details of a possible tsunami would suggest a thrust-mechanism for the earthquake; similar to the 1978 Santa Barbara earthquake (>M5) which had a left-lateral and north-dipping thrust mechanism. [5] Coulomb stress scenarios were developed using models for the December 8 earthquake along the San Andreas Fault and indicate there was an increase in stress on faults which geometries may be the source of the December 21 shock. This indicate the latter shock was likely triggered by the December 8 earthquake. [6]

San Andreas Fault

The San Andreas Fault in California. USGS - San Andreas fault zone.gif
The San Andreas Fault in California.

Based on tree-ring sampling, forests may have suffered some type of trauma, and were experiencing slow growth in 1812. Missing rings and crowns were discovered at around the same time. [7] These trees took several years or decades to fully recover and return to their normal stage. These affected trees were found only in close proximity to the San Andreas Fault; in an event of a strong earthquake, trees at a considerable distance should also display evidence of trauma. A plausible cause might be that during slippage, the roots of these trees were severed, thus reducing the intake of nutrients and water required for growth. The seismic shaking may also knock off branches and parts of the trees. [7]

It is believed that the San Juan Capistrano earthquake on December 8 triggered a second rupture on the San Andreas Fault on December 21. [8] The rupture on December 21 initiated in the south, and progressed northwards to Fort Tejon. Both events ruptured a total length of 170 km on the fault. [8] The northern end of the rupture is still uncertain because of the overlapping southern rupture end of the 1857 Fort Tejon earthquake, 44 years later. [8] [9]

However, if the earthquake was sourced from the San Andreas Fault, the aftershocks should not be felt around the coastal regions of California. The documented aftershocks were felt locally, and there were reports of "odd disturbances" in the sea. Another challenge to the San Andreas hypothesis source is the lack of damage at Santa Barbara during the much more powerful 1857 earthquake. The section involved in the 1857 earthquake was closer to Santa Barbara and Ventura but were not felt severely like in the 1812 earthquake. [7] [9] Claims of a tsunami and odd disturbances in the sea, can be attributed to an earthquake-triggered landslide. [10] [11]

San Cayetano Fault

The San Cayetano Fault in Southern California USGS - San Cayetano fault.gif
The San Cayetano Fault in Southern California

Located northwest of Los Angeles, the 40 km (25 mi) long San Cayetano Fault is a north dipping reverse fault that extends from Ventura to the Sespe Mountains. The fault comprises two segments separated by a right stepover near Fillmore. The eastern segment, known as the Modelo lobe, is expressed at the surface along the southern margin of the mountains west of Fillmore. Its surface rupture diminishes to the east of Piru. The western segment's surface expression is located considrably above the mountain base because the segment lies atop the south-dipping Sisar Blind Thrust Fault and a north-dipping blind thrust. The compression rate along the Ventura area is estimated at 6–7 mm (0.24–0.28 in) per year; accommodated by the San Cayetano and Oak Ridge faults. [12]

An epicenter proposed in the Santa Barbara Channel was based on reports of the large tsunami that flooded coastal communities. [7] A study along the San Cayetano Fault in Ventura County revealed evidence of a fresh slip dating between 1660 and 1813 and has been interpreted as a powerful earthquake that was generated by the fault. Trenching by Dolan and Rockwell revealed slip of 4.3 m (14 ft) along the surface rupture of this earthquake. The event may correspond to the earthquake of December 21 or one occurring just before the historical period. [12] Two large slip events were found at the trench dating back to the past 350 years along the fault. The magnitude of these events was estimated to be greater than Mw  7.0 and likely ruptured the entire length of the fault. [13]

Impact and aftermath

The first earthquake which may have been a foreshock, occurred at around 10:00–10:15 a.m.. At Mission La Purisima, padres, soldiers, and Native Indians ran out of the mission's buildings. [14] They were still outside when the mainshock struck fifteen minutes later. This time, the shaking intensity was much more violent. Bells of the mission church started ringing and the adobe walls began to fracture and collapse. At the mission, a large fissure carved through the slopes of a hill erupted mud and water. [15]

Ruins of the chapel at Mission La Purisima. Interior of the chapel of Mission La Purisima Concepcion, in ruins, ca.1904 (CHS-2259).jpg
Ruins of the chapel at Mission La Purisima.

Damage was reported at Mission Santa Ines, Mission Santa Barbara, Santa Barbara Presidio, Mission San Buenaventura (Ventura), and Mission San Fernando as well. [16] One person was killed by a falling boulder at Agua Caliente. At the various missions, many houses, churches, chapels, and other structures totally collapsed. [15] [17] Three adobe buildings were destroyed by the advancing tsunami. At Mission San Buenaventura and Mission Santa Barbara, the destruction was great, and a native man died when a building collapsed on him during an aftershock. [15]

The low death toll for this large earthquake was attributed to a foreshock which occurred 15 minutes before the mainshock. The foreshock had driven many people out of buildings that would collapse later. [18]

Devastation from this earthquake was comparable to the 1906 San Francisco and 1857 Fort Tejon earthquakes, but over a much smaller area. Frightened Chumash people on Santa Cruz and Santa Rosa islands fled to the mainland in their canoes and relocated there. [19] [20] For fears of another tsunami and aftershocks persisting, the missions were abandoned until April 1813. [10]

Tsunami

Over 60 km (37 mi) of the Santa Barbara shore was affected by the tsunami. At Refugio, the tsunami run-up was about 4 m (13 ft). Along the Santa Barbara and Ventura coast, the run-up height was about 2 m (6 ft 7 in). The captain of the Thomas Newland, a ship in Refugio Bay during the earthquake, watched as the sea receded and later returned in a wave that lifted the ship and dumped it at Refugio Canyon. The waves carried the ship back to sea. [21] [10] Run-up heights of 3–4 m (9.8–13.1 ft) were recorded at Gaviota, although eyewitness said the tsunami may have been up to 15.2 m (50 ft) high. [22] [23] The tsunami was also recorded at San Francisco and a ~4 m (13 ft) run-up may have occurred at Kona, Hawaii. [24]

See also

Related Research Articles

<span class="mw-page-title-main">Southern California</span> American geographic and cultural region

Southern California is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area as well as the Inland Empire. The region generally contains ten of California's 58 counties: Imperial, Kern, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, San Luis Obispo, and Ventura counties.

In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousands of instrumentally detectable aftershocks, which steadily decrease in magnitude and frequency according to a consistent pattern. In some earthquakes the main rupture happens in two or more steps, resulting in multiple main shocks. These are known as doublet earthquakes, and in general can be distinguished from aftershocks in having similar magnitudes and nearly identical seismic waveforms.

<span class="mw-page-title-main">Parkfield earthquake</span> Series of earthquakes in California, US

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, between 1857 and 1966. The most recent significant earthquake to occur here happened on September 28, 2004.

The 1857 Fort Tejon earthquake occurred at about 8:20 a.m. on January 9 in central and Southern California. One of the largest recorded earthquakes in the United States, 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, between Parkfield and Wrightwood.

<span class="mw-page-title-main">White Wolf Fault</span> Californian 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 fault with a left lateral (sinistral) component.

<span class="mw-page-title-main">2002 Denali earthquake</span> 7.9 magnitude; November 3, 2002

The 2002 Denali earthquake occurred at 22:12:41 UTC November 3 with an epicenter 66 km ESE of Denali National Park, Alaska, United States. This 7.9 Mw earthquake was the largest recorded in the United States in 37 years. The shock was the strongest ever recorded in the interior of Alaska. Due to the remote location, there were no fatalities and only one injury.

<span class="mw-page-title-main">San Jacinto Fault Zone</span> Southern Californian fault zone

The San Jacinto Fault Zone (SJFZ) is a major strike-slip fault zone that runs through San Bernardino, Riverside, San Diego, and Imperial Counties in Southern California. The SJFZ is a component of the larger San Andreas transform system and is considered to be the most seismically active fault zone in the area. Together they relieve the majority of the stress between the Pacific and North American tectonic plates.

The 1992 Cape Mendocino earthquakes occurred along the Lost Coast of Northern California on April 25 and 26. The three largest events were the M7.2 thrust mainshock that struck near the unincorporated community of Petrolia midday on April 25 and two primary strike-slip aftershocks measuring 6.5 and 6.6 that followed early the next morning. The sequence encompassed both interplate and intraplate activity that was associated with the Mendocino Triple Junction, a complex system of three major faults that converge near Cape Mendocino. The total number of aftershocks that followed the events exceeded 2,000.

<span class="mw-page-title-main">San Cayetano Fault</span> Seismic fault in California

The San Cayetano Fault is an east-west trending thrust fault in Ventura County, Southern California. It stretches for 45 kilometers (28 mi), north of the city of Ventura, near the Topatopa Mountains, Piru, Fillmore, Santa Paula, Sulphur Springs, and Ojai.

The 1812 San Juan Capistrano earthquake, also known simply as the Capistrano earthquake or the Wrightwood earthquake, occurred on December 8 at 15:00 UTC in Alta California. At the time, this was a colonial territory of the Spanish Empire. Damage occurred at several of the missions in the region of Pueblo de Los Ángeles, including Mission San Gabriel Arcángel and Mission San Juan Capistrano, where 40 parishioners were killed during the collapse of a church at an early morning service. Tree ring and paleoseismic evidence show that there is a strong likelihood that the earthquake originated along the Mojave segment of the San Andreas Fault near Wrightwood, but other faults have been suggested as the cause.

The 1925 Santa Barbara earthquake hit the area of Santa Barbara, California on June 29, with a moment magnitude between 6.5 and 6.8 and a maximum Mercalli Intensity of IX (Violent). It resulted in 13 deaths and destroyed the historic center of the city, with damage estimated at $8 million.

The 1838 San Andreas earthquake is believed to be a rupture along the northern part of the San Andreas Fault in June 1838. It affected approximately 100 km of the fault, from the San Francisco Peninsula to the Santa Cruz Mountains. It was a strong earthquake, with an estimated moment magnitude of 6.8 to 7.2, making it one of the largest known earthquakes in California. The region was lightly populated at the time, although structural damage was reported in San Francisco, Oakland, and Monterey. It is unknown whether there were fatalities. Based on geological sampling, the fault created approximately 1.5 meters of slip.

The 1898 Mare Island earthquake occurred in Northern California on March 30 at 23:43 local time with a moment magnitude of 5.8–6.4 and a maximum Mercalli intensity of VIII–IX (Severe–Violent). Its area of perceptibility included much of northern and central California and western Nevada. Damage amounted to $350,000 and was most pronounced on Mare Island, a peninsula in northern San Francisco Bay. While relatively strong effects there were attributed to vulnerable buildings, moderate effects elsewhere in the San Francisco Bay Area consisted of damaged or partially collapsed structures, and there were media reports of a small tsunami and mostly mild aftershocks that followed.

<span class="mw-page-title-main">2013 Craig, Alaska earthquake</span> Earthquake in Alaska and British Columbia

The 2013 Craig, Alaska earthquake struck on January 5, at 12:58 am (UTC–7) near the city of Craig and Hydaburg, on Prince of Wales Island. The Mw 7.5 earthquake came nearly three months after an Mw  7.8 quake struck Haida Gwaii on October 28, in 2012. The quake prompted a regional tsunami warning to British Columbia and Alaska, but it was later cancelled. Due to the remote location of the quake, there were no reports of casualties or damage.

<span class="mw-page-title-main">2021 Chignik earthquake</span> 7th largest earthquake in the US

An earthquake occurred off the coast of the Alaska Peninsula on July 28, 2021, at 10:15 p.m. local time. The large megathrust earthquake had a moment magnitude of 8.2 according to the United States Geological Survey (USGS). A tsunami warning was issued by the National Oceanic and Atmospheric Administration (NOAA) but later cancelled. The mainshock was followed by a number of aftershocks, including three that were of magnitude 5.9, 6.1 and 6.9 respectively.

The 2021 South Sandwich Islands earthquakes were a pair of powerful earthquakes, followed by many strong aftershocks which struck along the South Sandwich Trench in August 2021. The quakes measured 7.5 and 8.1 on the moment magnitude scale, according to the United States Geological Survey. The mainshock is tied with another event in 1929 as the largest earthquake ever recorded in the South Atlantic region, and is tied with the 2021 Kermadec Islands earthquake as the second largest earthquake of 2021.

Ruth Harris is a scientist at the United States Geological Survey known for her research on large earthquakes, especially on how they begin, end, and cause the ground to shake. In 2019, Harris was elected a fellow of the American Geophysical Union who cited her "for outstanding contributions to earthquake rupture dynamics, stress transfer, and triggering".

The 1979 Saint Elias earthquake occurred near noon local time on 28 February. It measured Mw 7.4–7.6. Though the maximum recorded Modified Mercalli intensity was VII, damage was minimal and there were no casualties due to the remoteness of the faulting. The epicenter lies near the Alaskan border between the United States and Canada.

The 1992 Joshua Tree earthquake occurred at 9:50:25 p.m. PDT on April 22 in Southern California. The magnitude 6.2 earthquake struck under the Little San Bernardino Mountains, near the town of Joshua Tree, California. Though no deaths were reported, the earthquake caused 32 injuries. A maximum Mercalli intensity of VII was observed in Joshua Tree and caused light to moderate damage. The event preceded the Landers and Big Bear earthquakes by two months but is now recognized as the beginning of a series of major earthquakes that culminated in two events on June 28, 1992.

References

  1. ↑ Jerry L. Coffman; Carl A. Von Hake; Carl W. Stover (1973), Earthquake History of the United States (Report), Publication, Boulder, CO: U.S. Department of Commerce, National Oceanic and Atmospheric Administration; U.S. Department of the Interior, Geological Survey
  2. ↑ "The December 21, 1812 Earthquake". Southern California Earthquake Data Center. 31 January 2013. Retrieved 23 November 2020.
  3. ↑ National Geophysical Data Center (1972). "Significant Earthquake Information". National Geophysical Data Center / World Data Service (NGDC/WDS): NCEI/WDS Global Significant Earthquake Database. NOAA National Centers for Environmental Information. doi:10.7289/V5TD9V7K . Retrieved 24 November 2020.
  4. ↑ Fisher, Michael A.; Sorlien, Christopher C.; Sliter, Ray W. (1 January 2009). "Potential earthquake faults offshore Southern California, from the eastern Santa Barbara Channel south to Dana Point". In Lee, H.J.; Normark, W.R. (eds.). Earth Science in the Urban Ocean: The Southern California Continental Borderland. Geological Society of America Special Papers. Vol. 454. Geological Society of America. doi:10.1130/2009.2454(4.4). ISBN   9780813724546 – via GeoScienceWorld.
  5. ↑ Deng, Jishu; Sykes, Lynn R. (1996). "Triggering of 1812 Santa Barbara Earthquake by a Great San Andreas Shock Implications for future seismic hazards in southern California". Geophysical Research Letters. 23 (10): 1155–1158. Bibcode:1996GeoRL..23.1155D. doi:10.1029/96GL00738.
  6. ↑ Deng, Jishu; Sykes, Lynn R. (1996). Triggering of 1812 Santa Barbara Earthquake by a Great San Andreas Shock: Implications for future seismic hazards in southern California. Geophysical Research Letters, 23(10), 1155–1158. doi : 10.1029/96gl00738
  7. 1 2 3 4 Gordon C. Jacoby Jr.; Paul R. Sheppard; Kerry E. Sieh (8 July 1988). "Irregular Recurrence of Large Earthquakes Along the San Andreas Fault: Evidence from Trees" (PDF). Science. 241 (4862): 196–199. Bibcode:1988Sci...241..196J. doi:10.1126/science.241.4862.196. PMID   17841050. S2CID   28944224.
  8. 1 2 3 Toppozada, Tousson; Branum, David (2004). "California earthquake history". Annals of Geophysics. 47.
  9. 1 2 T. R. Toppozada; D. M. Branum; M. S. Reichle; C. L. Hallstrom (October 2002). "San Andreas Fault Zone, California: M>=5.5 Earthquake History" (PDF). Bulletin of the Seismological Society of America. 92 (7): 2555–2601. Bibcode:2002BuSSA..92.2555T. doi:10.1785/0120000614.
  10. 1 2 3 Rasmussen, Cecilia (9 January 2005). "1812 California Tsunami Carried a Ship Inland". Los Angeles Times. Retrieved 23 November 2020.
  11. ↑ Lloyd, Jonathan (23 January 2018). "List: Historic Tsunamis on California's Coast". NBC Los Angeles. Retrieved 23 November 2020.
  12. 1 2 Dolan, James F.; Rockwell, Thomas K. (1 December 2001). "Paleoseismologic Evidence for a Very Large (Mw >7), Post-A.D. 1660 Surface Rupture on the Eastern San Cayetano Fault, Ventura County, California: Was This the Elusive Source of the Damaging 21 December 1812 Earthquake?". Bulletin of the Seismological Society of America . 91 (6): 1417–1432. Bibcode:2001BuSSA..91.1417D. doi:10.1785/0120000602. ISSN   1943-3573. Wikidata   Q97924725.
  13. ↑ Dolan, James F. Paleoseismology and Seismic Hazards of the San Cayetano Fault Zone (PDF) (Report). Department of Earth Sciences, University of Southern California.
  14. ↑ "The 1812 Santa Barbara Earthquake: In Brief". UCSB. Retrieved 23 November 2020.
  15. 1 2 3 "large ground crack". UCSB. Retrieved 23 November 2020.
  16. ↑ Devich, Mike (21 Dec 2012). "1812 quake destroyed original mission". Lompoc Record. Retrieved 14 December 2020.
  17. ↑ "21 December 1812 M7.1". UCSB. Retrieved 23 November 2020.
  18. ↑ Carl W Stover, Jerry L Coffman (1993). "Seismicity of the United States, 1568-1989 (revised)". U.S. Government Printing Office.
  19. ↑ Meyers, Talya (2 August 2017). "Potential Earthquake Worries in Santa Barbara Channel". Santa Barbara Independent. Retrieved 23 November 2020.
  20. ↑ "The Great 1812 Santa Barbara Earthquake and Tsunami". WatchOutCity. 28 November 2019. Retrieved 20 December 2020.
  21. ↑ "The 1812 Santa Barbara Earthquake: Tsunami!". UCSB. Retrieved 23 November 2020.
  22. ↑ Legg, Mark R.; Borrero, Jose C.; Synolakis, Costas E. (2004). "Tsunami Hazards Associated with the Catalina Fault in Southern California" (PDF). Earthquake Spectra. 20 (3): 917–950. Bibcode:2004EarSp..20..917L. doi:10.1193/1.1773592. S2CID   110051107.
  23. ↑ "Tsunami Event Information". NOAA NCEI. Retrieved 24 November 2020.
  24. ↑ Borrero, Jose C.; Dolan, James F.; Synolakis, Costas Emmanuel (2001). "Tsunamis within the Eastern Santa Barbara Channel". Geophysical Research Letters. 28 (4): 643–646. Bibcode:2001GeoRL..28..643B. doi: 10.1029/2000GL011980 . S2CID   129929406.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.