1812 San Juan Capistrano earthquake

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1812 San Juan Capistrano earthquake
Relief map of California.png
Green pog.svg
San Buenaventura
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San Gabriel
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San Juan Capistrano
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San Diego
UTC  time1812-12-08 15:00:00
USGS-ANSS ComCat
Local dateDecember 8, 1812 (1812-12-08)
Local time07:00 [1]
Magnitude6.9 Mla [1]
7.5 Mw [2]
TypeUnknown
Areas affected Alta California
New Spain
Total damageModerate [3]
Max. intensity IX (Violent) [4] [5]
Casualties40 killed [1]

The 1812 San Juan Capistrano earthquake, also known simply as the Capistrano earthquake or the Wrightwood earthquake, [6] 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.

Contents

Several studies in the 1980s placed the shock along the southern Newport–Inglewood Fault near the zone of highest reported intensity. This fault is near the coast and the most significant damage at the missions, but later work at trench sites along the San Andreas Fault excluded it for this large to very large shock. Dynamic rupture modelling made possible another proposal in the 2010s involving a dual rupture scenario with both the San Andreas and San Jacinto Fault Zones. Each of these studies worked with limited data, and the effects of the shock and various fault rupture details led to Mercalli intensities of VII (Very strong) to IX (Violent) being proposed. Magnitudes from 6.9 Mla on the low end to 7.5 Mw on the high end were also presented.

Tectonic setting

The primary tectonic feature in California is the strike-slip San Andreas (SAF) system of faults that form part of the diffuse Pacific–North American plate boundary. This transform fault trends south-southeast through much of northern and central California, but turns more southeasterly at the southern end of the California Coast Ranges at a prominent restraining bend. Southeast of this bend the SAF borders the Mojave Desert then bisects the San Gabriel and San Bernardino Mountains at Cajon Pass, where the active San Jacinto Fault Zone diverges from the SAF. The San Jacinto Mountains and the Salton Sea lie between the two faults as they continue to the southeast towards the Mexico–United States border. The Newport–Inglewood Fault, a part of the San Andreas system that is positioned near the coast along the western extremity of the Los Angeles Basin, is a discontinuous strike-slip fault similar to the San Jacinto Fault. [7]

Earthquake

The Newport-Inglewood-Rose Canyon Fault Zone USGS - Newport-Inglewood-Rose Canyon fault zone.gif
The Newport-Inglewood-Rose Canyon Fault Zone
The San Andreas Fault USGS - San Andreas fault zone.gif
The San Andreas Fault
The San Jacinto Fault Zone USGS - San Jacinto Fault Zone.gif
The San Jacinto Fault Zone

Source fault

In the 1980s several seismologists attributed the source of the event to the southern Newport–Inglewood Fault due to its proximity to the zone of greatest damage at Mission San Juan Capistrano. The northern portion of the fault was excluded as a potential source due to a lack of damage at San Buenaventura. Other more distant sources have also been proposed, including the Mojave segment of the SAF to the north of San Juan Capistrano, substantiated by tree distress evidence preserved in tree rings along the fault zone and paleoseismic evidence in an investigative trench at Pallet Creek. Another scenario was proposed after a researcher noted the great distance between the SAF and the zone of damage near the coast. After a paleoseismic investigation and simulations, it was proposed that a joint rupture of both the SAF and the San Jacinto Fault Zone to the southeast more closely matched the damage pattern than a SAF-only rupture. [8] [9]

Newport–Inglewood Fault

In support of the southern Newport–Inglewood Fault as the source, Toppozada & Real 1981 presented a simple isoseismal map with one elongated ring oriented northwest–southeast roughly parallel to the coastline and centered on the fault. The single isoseismal (a line depicting an area of equal intensity) shows the intensity VII (Very strong) boundary for the event, which is an ellipse that includes Mission San Juan Capistrano, Mission San Gabriel Arcángel, and Mission San Fernando Rey de España at the extreme northwest end. From a modern-day perspective, this intensity level covers all of Orange County, most of southern Los Angeles County, and insignificant portions of San Bernardino, Riverside, and San Diego Counties. After analyzing the intensity data that were derived from the mission's minimal reports and by modeling ground conditions and known faults, Evernden & Thompson 1985 also singled out the southern Newport–Inglewood Fault as the source. [4] [10]

San Andreas Fault

Influenced by the work of several dendrochronologists and a seismologist who examined trauma to trees near Wrightwood, Toppozada et al. 2002 came about in support of the SAF as the source. Jacoby, Sheppard, & Sieh 1988 gained a more thorough understanding of the most recent events and a potential rupture length of the SAF by investigating damage to trees, which been associated with intensity VIII (Severe) shaking within several kilometers of a source fault. Seventy trees were examined and nine of the trees along a 7.5 mi (12 km) section experienced some form of trauma beginning in 1813, including two with crown loss. All were within 66 ft (20 m) of the fault. Other sources for the damage were ruled out, including disease, lightning, wind, and fire. Severe shaking was also excluded because trees outside of this narrow zone would also have similar effects. The researchers' theory was that right-lateral displacement on the SAF had damaged their root systems. [2] [11]

San Andreas and San Jacinto Faults

By the 2010s, the shift of attention from the Newport–Inglewood Fault to the SAF was cemented, with numerous other paleoseismic investigations validating that slip along the SAF, possibly as far north as Elizabeth Lake, was responsible for the event. [12]

Damage

Several of the Roman Catholic missions in the area experienced heavy damage. The bell structure at Mission San Gabriel Arcángel collapsed and at Mission San Juan Capistrano the Great Stone Church was destroyed and forty Native Americans were killed as the earthquake happened during the first service. The service was being held on a Tuesday, for the Feast of the Immaculate Conception celebration, which is universally celebrated every December 8. [1] [13]

Intensity

Toppozada & Real 1981 shows the most conservative estimates for the intensity of the event, with Mission San Luis Rey and Mission San Diego both indicating that the shock was felt only, and no clarification of whether it was weak, light, or moderate. Well away from the proposed epicenter, the San Bernardino Valley may have experienced intensity VI (Strong) shaking, and a maximum intensity of VII was listed for Mission San Juan Capistrano, Mission San Gabriel Arcángel, and Mission San Fernando Rey de España. Mission San Buenaventura lay outside the ring, but is annotated with possibly also having experienced intensity VII effects. Stover & Coffman 1993 and the National Geophysical Data Center's Significant Earthquake Database both show a maximum intensity of VIII (Severe), but neither correlate intensity to location. The NGDC's Earthquake Intensity Database indicates that a maximum of IX (Violent) was experienced at San Gabriel and San Juan Capistrano. [5] [3]

Other events

Thirteen days later, the Ventura earthquake with an estimated magnitude of 7.1–7.5 struck. It generated a 3.4-meter tsunami around the Santa Barbara coast. The damage from that was moderate and significantly less deadly. That quake may have been triggered by the Wrightwood earthquake however, the location of its epicenter remains uncertain. [14]

See also

Related Research Articles

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">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.

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

The Rose Canyon Fault is a right-lateral strike-slip fault running in a north-south direction through San Diego County, California.

The 1940 El Centro earthquake occurred at 21:35 Pacific Standard Time on May 18 in the Imperial Valley in southeastern Southern California near the international border of the United States and Mexico. It had a moment magnitude of 6.9 and a maximum perceived intensity of X (Extreme) on the Mercalli intensity scale. It was the first major earthquake to be recorded by a strong-motion seismograph located next to a fault rupture. The earthquake was characterized as a typical moderate-sized destructive event with a complex energy release signature. It was the strongest recorded earthquake in the Imperial Valley, causing widespread damage to irrigation systems and killing nine people.

The 1948 Desert Hot Springs earthquake occurred on December 4 at 3:43 p.m. Pacific Standard Time with a moment magnitude of 6.4 and a maximum Mercalli intensity of VII. The shock was felt from the central coast of California in the north, and to Baja California in the south, and came at a time when earthquake research in southern California resumed following the Second World War. It was one of two events in the 20th century that have occurred near a complex region of the southern San Andreas Fault system where it traverses the San Gorgonio Pass and the northern Coachella Valley. Damage was not severe, but some serious injuries occurred, and aftershocks continued until 1957.

The 1991 Sierra Madre earthquake occurred on June 28 at 07:43:55 local time with a moment magnitude of 5.6 and a maximum Mercalli intensity of VII. The thrust earthquake resulted in two deaths, around 100 injuries, and damage estimated at $33.5–40 million. The event occurred beneath the San Gabriel Mountains on the Clamshell–Sawpit Fault, which is a part of the Sierra Madre–Cucamonga Fault System. Instruments captured the event at a number of strong motion stations in Southern California.

The 1986 North Palm Springs earthquake occurred on July 8 at 02:20:44 local time with a moment magnitude of 6.0 and a maximum Mercalli Intensity of VII. The shock occurred in a complex setting along the San Andreas Fault Zone where it bisects San Gorgonio Mountain and San Jacinto Peak at the San Gorgonio Pass and was the first in a series of three earthquakes that affected southern California and the northern Owens Valley in July 1986. Numerous strong motion instruments recorded the event, one of which showed relatively high accelerations. Between 29 and 40 people were injured, and financial losses were estimated to be in the range of $4.5–6 million.

The 1892 Vacaville–Winters earthquakes occurred in northern California as a large doublet on April 19 and April 21. Measured on a seismic scale that is based on an isoseismal map or the event's felt area, the 6.4 Mla and 6.2 Mla  events were assigned a maximum Mercalli intensity of IX (Violent), and affected the North Bay and Central Valley areas. The total damage was estimated to be between $225,000 and 250,000 and one person was killed. No evidence of fault movement on the surface of the ground was observed as a result of either of the strong shocks. Both occurred in the domain of the San Andreas strike-slip system of faults, but their focal mechanism is uncertain.

<span class="mw-page-title-main">1918 San Jacinto earthquake</span> Earthquake in Southern California

The 1918 San Jacinto earthquake occurred in extreme eastern San Diego County in Southern California on April 21 at 14:32:29 local time. The shock had a moment magnitude of 6.7 and a maximum Mercalli intensity of IX (Violent). Several injuries and one death occurred with total losses estimated to be $200,000.

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.

<span class="mw-page-title-main">Sierra Madre Fault Zone</span> Seismic fault in Southern California

Situated at the boundary to the San Gabriel Valley and San Fernando Valley, the Sierra Madre Fault Zone runs along the southern edge of the San Gabriel Mountains for a total of 95 kilometers (59 mi), where the northwesternmost 19 km (12 mi) comprises the San Fernando Fault. A 1980s paleoseismic study that included a trench investigation and mapping revealed that a major earthquake had most likely not occurred to the east of the San Fernando rupture area for at least the last several thousand, and possibly the last 11,000 years.

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">1812 Ventura earthquake</span> Magnitude 7.1 earthquake in Alta California

The 1812 Ventura earthquake occurred on the morning of December 21 at 11:00 Pacific Standard Time (PST). The 7.1–7.5 magnitude 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. 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 the 8th of December the same year. Both events are thought to have been related.

The 1968 Borrego Mountain earthquake occurred on April 8, at 18:28 PST, near the unincorporated community of Ocotillo Wells in San Diego County. The moment magnitude (Mw ) 6.6 strike-slip earthquake struck with a focal depth of 11.1 km (6.9 mi). Damage was relatively moderate, and the mainshock was assigned a maximum Modified Mercalli intensity (MMI) of VII. Shaking was felt in Nevada, and Arizona. It was the largest earthquake to strike California since 1952, and its display of afterslip became the subject of scientific interest.

The 1872 Amik (Antakya) earthquake occurred on April 3 with an epicenter within the Amik Valley in the Ottoman Empire. Earthquake had an estimated magnitude of Mw  7.0–7.2 or Ms  7.2 and maximum MSK 64 rating of XI (Catastrophic). Turkey and Syria were devastated by this earthquake, and the region lost at least 1,800 residents.

The 1899 San Jacinto earthquake occurred on Christmas morning at 04:25 local time in Southern California. The estimated moment magnitude 6.7 earthquake had an epicenter located 10 miles southeast of San Jacinto. The earthquake had a maximum Mercalli intensity of IX (Violent). Severe damage occurred, amounting to US$50,000, as well as six fatalities.

The 1915 Imperial Valley earthquakes were two destructive shocks centered near El Centro, California on June 22. The earthquakes measured Ms 6.25 and occurred nearly one hour apart at 19:59 and 20:57 PST. Both shocks were assigned VIII (Severe) on the Modified Mercalli intensity scale. Heavy damage occurred in the areas of Mexicali and El Centro, amounting to $900,000. At least six people were killed in the earthquakes.

<span class="mw-page-title-main">1902 Shamakhi earthquake</span>

The 1902 Shamakhi earthquake occurred on 13 February with a surface-wave magnitude of 6.9 and a maximum felt Modified Mercalli intensity of IX (Violent). Up to 2,000 people died and thousands more were injured in the Shemakha uezd within the Baku Governorate of the Russian Empire. About 7,439 buildings were damaged or destroyed in the city and surrounding villages. Shamakhi had been devastated by earlier earthquakes in 1806, 1859 and 1872. It is one of the most destructive earthquakes in Azerbaijan.

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. 1 2 3 4 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, 100
  2. 1 2 Jacoby, Jr., G. C.; Sheppard, P. R.; Sieh, K. E. (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
  3. 1 2 National Geophysical Data Center / World Data Service (NGDC/WDS) (1972), "Significant Earthquake Information", NCEI/WDS Global Significant Earthquake Database (Data Set), NOAA, National Centers for Environmental Information, doi:10.7289/V5TD9V7K
  4. 1 2 Toppozada, T. R.; Real, C. R. (1981), Preparation of isoseismal maps and summaries of reported effects for pre-1900 California earthquakes (print), Open-File Report 81-262, United States Geological Survey, pp. 16, 33, 134–136
  5. 1 2 NGDC, Earthquake Intensity Database: 1638–1985, National Geophysical Data Center
  6. ↑ City of Huntington Beach - City of Huntington Beach Miscellaneous Historical Data
  7. ↑ Yeats, R. (2012), Active Faults of the World, Cambridge University Press, pp. 19, 80–83, 96–107, ISBN   978-0521190855
  8. ↑ Wilcox, K. (April 5, 2016), "Research reveals a dual fault threat", Civil Engineering, American Society of Civil Engineers, archived from the original on July 2, 2017
  9. ↑ Ellsworth, W. L. (1990). "Earthquake history, 1769–1989". The San Andreas Fault System, California – USGS Professional Paper 1515. United States Geological Survey. p. 157. ISBN   978-0607716269.
  10. ↑ Evernden, J. F.; Thompson, J. M. (1985), "Predicting Seismic Intensities" (PDF), Evaluating Earthquake Hazards in the Los Angeles Region—An Earth-Science Perspective, U.S. Geological Survey Professional Paper 1360, United States Geological Survey, pp. 178–180
  11. ↑ Toppozada, T. R.; Branum, D. M.; Reichle, M. S.; Hallstrom, C. L. (2002), "San Andreas Fault Zone, California: M≥5.5 Earthquake History" (PDF), Bulletin of the Seismological Society of America, 92 (7): 2574–2578, Bibcode:2002BuSSA..92.2555T, doi:10.1785/0120000614
  12. ↑ Lozos, J. C. (2016), "A case for historic joint rupture of the San Andreas and San Jacinto faults", Science Advances , 2 (3): 196–199, Bibcode:2016SciA....2E0621L, doi:10.1126/sciadv.1500621, PMC   4803493 , PMID   27034977
  13. ↑ Bolt, B. (2005), Earthquakes: 2006 Centennial Update – The 1906 Big One (Fifth ed.), W. H. Freeman and Company, pp. 33, 326, ISBN   978-0716775485
  14. ↑ "The December 21, 1812 Earthquake". SCEDC. Retrieved January 29, 2021.
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