Earthquakes In San Diego?

- Per the maps below, the San Diego area has a low probability of a major earthquake compared to California regions to the north of us.

- In the last 200 years in San Diego, there have been no major earthquakes, and five earthquakes that caused minor damage.

San Diego Natural History Museum - Good summary of earthquake information.- http://www.sdnhm.org/research/paleontology/sdfaults.html

In modern times the strongest recorded quake (seismographs were not developed until 1934) in coastal San Diego County was the M5.3 temblor that occurred on 13 July 1986 on the Coronado Bank Fault, 25 miles offshore of Solana Beach.

San Diego Tribune - http://www.signonsandiego.com/news/metro/20080729-1505-bn29quakesid.html

This is a list of some earthquakes that were centered or felt in San Diego County.

Nov. 22, 1800: The first recorded earthquake struck the San Diego region. The quake, believed to have a 6.5 magnitude, occurred on the Rose Canyon fault offshore from Oceanside. It cracked adobe walls at the missions of San Diego de Alcala and San Juan Capistrano.

May 25, 1803: An earthquake damaged the San Diego Mission church.

May 27, 1862: A 6.0 earthquake hit the San Diego region centered on the Rose Canyon or Coronado band faults. The quake cracked adobe buildings in Old Town and damaged the Point Loma lighthouse.

March 10 1933: The Long Beach earthquake, estimated magnitude 6.4, killed 120 or more in Southern California. No deaths or damage reported in San Diego.

Feb. 9, 1956: A magnitude 6.8 earthquake centered east of Ensenada rocked San Diego. It was the strongest shock felt in the area since 1940. Minor damage, but no injuries were reported in the county.

July 13, 1986: The strongest earthquake known to strike San Diego County hit, registering 5.4. It was centered off the coast of Oceanside on the Coronado Bank fault.
In modern times the strongest recorded quake (seismographs were not developed until 1934) in coastal San Diego County was the M5.3 temblor that occurred on 13 July 1986.

June 12, 2005: A magnitude 5.6 earthquake centered six miles southeast of Anza, a town about nine miles north of the San Diego County line, shook Southern California and cracked the wall and foundation of a North County fire station.

County of San Diego - http://www.co.san-diego.ca.us/oes/disaster_preparedness/oes_jl_earthquakes.html

"Every year approximately 500 earthquakes occur in the state of California that are large enough to be felt. San Diego County, in comparison to other southern California areas, has sparse seismicity. However, since 1984, earthquake activity in San Diego County has doubled over that of the preceding 50 years.

Ongoing field and laboratory studies suggest the largest credible earthquake predicted for the coastal and metropolitan areas is a M7.2 on the Rose Canyon Fault and a M7.6 from either the Elsinore Fault or the San Jacinto Fault in the north and east county areas. In addition, studies suggest the following maximum likely magnitudes for local faults: La Nacion (M6.2 to 6.6), Coronado Bank (M6.0 to 7.7), San Diego Trough (M6.1 to 7.7), San Clemente (M6.6 to 7.7)."

USGS - http://earthquake.usgs.gov/research/hazmaps/haz101/faq/psha04.php :

Using the data available at our web site for Chico, California, and for San Diego, California, one can get an idea of the approximate probability of strong, damaging ground motion at each location. Inspecting peak ground acceleration maps for ground motions having 10 percent probability of being exceeded in 50 years and ground motions having 2 percent probability of being exceeded in 50 years, we would find approximately that around San Diego, the ground motion that has 10 percent probability of being exceeded in 50 years is about equal to the ground motion around Chico that has 2 percent probability of being exceeded in 50 years. That ground motion is 30 percent g.

From one of the answers at the Frequently-Asked Questions page at our site,
What is "% g"?  What is the relation to building damage?

We find that an approximate threshold for shaking that causes damage is 10 percent g. So, 30 percent g is very strong shaking indeed and has about 1 chance in 10 of occurring in San Diego in 50 years. In 20 years this would be about 1 chance in 25. In Chico, this level of shaking has about 1 chance in 50 of occurring in 50 years or about 1 chance in 125 in 20 years. This may be a reasonable number to use for the likelihood of the occurrence of a big, nearby earthquake.

However, you know, earthquake shaking doesn't kill people; falling buildings kill people. Earthquake shaking double this level was experienced in Santa Cruz at the time of the Loma Prieta earthquake (world series earthquake) and in well-built homes no one was killed. In California, because of the level of seismic engineering, the likelihood of widespread or long-lasting disorder after an earthquake is pretty low, so maybe earthquake probability should not be a prime consideration in deciding where to move."

Maps per USGS - http://earthquake.usgs.gov/

Recent earthquakes in the San Diego area:  http://quake.usgs.gov/recenteqs/Maps/117-33.htm

Earthquake Insurance:

http://www.signonsandiego.com/uniontrib/20050922/news_1b22quake.html

"The CEA holds 66 percent of the earthquake insurance market in California." (California Earthquake Authority).  "The Legislature created the semipublic agency after the Northridge quake left many homeowners in legal tussles with insurance companies unwilling to cover the damage to their properties."

"Earthquake insurance rates are not based on a home's value, but rather on the cost of rebuilding. So while the CEA sells policies to homeowners through participating private insurers, the insurance companies are responsible for any payout the authority can't handle after a major disaster."

http://moneycentral.msn.com/content/Insurance/Insureyourhome/P59648.asp

http://unitedpolicyholders.org/buyingtips/tip_buy_eq.html

Revised 3/28/09

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