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A Brief California Earthquake History

A Brief California Earthquake History
 

Residents in California are very aware that earthquakes occur on a regular basis, simply because the state has so many active faults.  The San Andreas and Hayward Faults are the most well-known, however there are actually more than one hundred active faults that lie underground throughout the entire state.  California has a unique landscape, and much of it is a result of the earth’s movement around these faults.  While California experiences many seismic tremors on a regular basis, many tremors are not even felt by residents; they are only picked up by very sensitive seismographs. Periodically, over the last three hundred fifty years, California has felt the violent shaking of more than a few powerful earthquakes – quakes that could be described as a “BIG ONE”.  Each of the California temblors bulleted below is believed to be a “BIG ONE” in the documented earthquake history along the West Coast.

  • Records show that the earliest recorded quake in California occurred in 1769.  Four forceful shocks were recorded, with the epicenter thought to be close to the San Andreas Fault, approximately 30 miles southeast of Los Angeles.  Scientific research has determined that this particular quake raised the shoreline in Orange County close to eleven feet at some points.
  • Many large trees came down and buildings were leveled as a result of a powerful earthquake near Fort Tejon in January, 1857.  The damage was insignificant as the area was minimally populated at that point in California history.   The powerful forces of this temblor actually ruptured 225 miles of the San Andreas Fault and it is currently the largest recorded seismic activity in California with a possible magnitude of 8.0.
  • In October 1868, another powerful earthquake killed many people in the area of Hayward and San Leandro.  It is the last powerful quake to happen in the Hayward Fault Zone area and almost every building in Hayward was damaged or destroyed. Until the 1906 San Francisco earthquake, this earthquake was called “the great earthquake”.
  • Historical records show that the most destructive earthquake to hit in California occurred on April 18, 1906.  This 7.9 magnitude earthquake happened in San Francisco and caused the death of more than 3000 people.  Damage was massive throughout the entire city as buildings crumbled to the ground and sadly, additional devastation was caused by rampant fires that were a direct result of the underground movement of the Earth.  A 296 mile rupture along the northern segment of the San Andreas Fault was caused by this particular temblor.
  • In May 1940, Imperial Valley, located in southern California, felt another powerful earthquake (7.1 magnitude).   The rocking and rolling of this seismic activity damaged at least 80% of the buildings in the area.  The business district was devastated and many properties there were condemned.
  • The most powerful earthquake of the 20th century to hit southern California occurred in July, 1952.  Both the towns of Arvin and Tehacapi took devastating hits from this temblor that occurred along the White Wolf fault.  This violent quake measured 7.7 on the Richter scale and caused an estimated $60 million in property damage.
  • On October 17, 1989, the Loma Prieta earthquake (6.9 on the Richter scale) rocked northern California from Monterey to San Francisco.  While the seismic activity lasted only a few moments, it was powerful enough to crumple highways and many commercial properties, causing property loss of more than $6 billion.
  • In the early morning hours of January 17, 1994, the Northridge earthquake rocked the San Fernando Valley.  Due to the damage caused by magnitude (6.7) of this quake, more than 20,000 people were displaced.  Personal and business economic losses were estimated to be approximately $20 billion.

Many scientists are expecting the next potentially catastrophic temblor could happen within the next ten to twenty years.  Even though residents, business owners and commercial property owners are generally aware that the possibility of a “BIG ONE” exists, earthquakes often catch people by surprise.  Because the possibility of major loss exists when the earth violently moves and shakes, California commercial property owners should make sure they have done everything possible to protect their property and their tenants before the next powerful earthquake occurs.  The California earthquake history bulleted above is just a short list of seismic activity that has occurred on the West Coast.   It is important to note that just the few details listed show that fatality rates and property damage estimates substantially increase as the population density increases.   Many commercial properties that were designed and built more than twenty years ago were not constructed to withstand the mighty forces of a mega-quake.

If you are a commercial property owner located in the densely populated metropolitan area of Los Angeles, consider reinforcing your building before the next “BIG ONE” strikes.  The experienced team at Saunders Commercial Seismic Retrofit is available to provide a complete multi-faceted inspection of your particular building and to complete any maintenance and renovations necessary to retrofit your property. If you have questions about strengthening your property with an earthquake retrofitting or want to schedule a thorough building inspection, today is the day to make a call to the professionals at Saunders Commercial Seismic Retrofit!

Southern California Office

(949) 646-0034

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