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Powerful Earthquakes in the 20th Century

Powerful Earthquakes in the 20th Century
 

Earthquakes happen throughout California on a regular basis.  The San Andreas and Hayward Faults are the most well-known, however there are more than one hundred different faults located throughout the state.  While most seismic activity is never felt by residents, thousands of tiny earthquakes are detected each year.  Much of the distinctive landscape in California is a result of the far-reaching set of faults that lie just under the surface of this great state.  Throughout the course of California’s recent recorded history (200+ years), a number of powerful earthquakes have been documented.  Each of the earthquakes listed below occurred in the 20th century and could be considered a “BIG ONE” in the history of California’s seismic activity.

  • The most destructive earthquake to hit California was the infamous 7.9 magnitude San Francisco earthquake that occurred in April 1906.  Many people perished in this earthquake and the resulting damage was extensive throughout the entire city of San Francisco.  Raging fires spread throughout the city as a result of the quake’s destructive force, increasing the devastation almost tenfold. It was estimated that over $500 million in damages occurred with this particular seismic activity.  In addition, this quake brought about a 296 mile rupture along the northern segment of the San Andreas Fault.

  • The city of Santa Barbara experienced $8 million in damage and 13 fatalities from a powerful offshore earthquake in June 1925.  The epicenter of this 6.3 magnitude shock occurred on an extension of the Mesa Fault in the Santa Barbara Channel.

  • The city of Long Beach suffered more than $40 million in damages and at least 115 deaths as a result of a major earthquake (estimated magnitude – 6.3) in March of 1933.  This earthquake eliminated any doubts and suspicions about the need for stronger, earthquake resistant buildings in California.  Most of the destruction occurred in heavily settled areas between Long Beach and the industrial areas south of Los Angeles.   Poorly planned building structures and unfavorable geological conditions were the primary causes for much of the major damage.  Many of the fatalities occurred as people ran out of buildings and were hit by flying and falling debris.

  • The Imperial Valley in southern California experienced a major earthquake (7.1 magnitude) in May, 1940.   This earthquake killed nine people and damaged 80 percent of the buildings in the area at a cost of nearly $6 million dollars.  Most of the commercial properties in the business areas were condemned, and a number of long-standing homes sustained serious damage.  The Imperial Valley quake brought about a 40 mile rupture along the Imperial Fault, which is part of the San Andreas Fault system.  This earthquake was the first strong test of public schools designed to be earthquake-resistant after the 1933 Long Beach earthquake.  Fifteen earthquake-resistant public schools in the area had no obvious damage.

  • In July, 1952, the towns of Tehacapi and Arvin were hit by a mighty earthquake along the White Wolf fault, measuring 7.7 on the Richter scale.  This earthquake, known as the Kern County earthquake, killed twelve people and caused injury to many more residents.  In addition, $60 million in property damage was caused by its powerful shaking.  The Kern County quake was the most powerful seismic activity to hit Southern California in the 20th century and the largest in the U.S. since San Francisco’s great quake in 1906.

  • On October 17, 1989, the Loma Prieta earthquake brought an end to several decades of tranquility in the Bay Area.  Just before the third game of the 1989 World Series was to begin that evening in San Francisco, a 6.9 magnitude earthquake rocked northern California from Monterey to San Francisco.  In just a few short moments, this earthquake collapsed highways and buildings, killing 63 people and causing more than $6 billion in property loss.

  • The 6.7 magnitude Northridge earthquake on January 17, 1994, produced the strongest ground motions ever instrumentally recorded in an urban setting in North America.  It displaced more than 20,000 people from their homes in a modern urban environment that was generally thought to be designed for better seismic resistance.  The overall destruction was extensive, portions of major freeways crumpled, and commercial office buildings and parking garages collapsed as a result of this particular seismic activity. Damage to wood-frame apartment structures was another widespread issue, particularly to buildings with “soft” first floor or lower-level parking areas.  There were 57 deaths and economic losses were estimated at $67 billion, making it one of the costliest natural disasters in U. S. history.

Can we predict when the next “BIG ONE” is coming?

Geologists predict that the next BIG, and possibly catastrophic, earthquake could occur within the next twenty to thirty years.  Earthquakes typically catch people off-guard, therefore commercial property owners should protect their property and their tenants now from the potential destruction that might happen during powerful seismic activity.  The California earthquake history listed above is just a short record of the earthquake activity that occurred in the last century.   With the details from these BIG ONES, along with other seismic activity, we know that fatality rates and property damage estimates will certainly increase as the population density rises throughout the state of California.

Don’t wait for the next powerful quake to address the weaknesses in your Bay Area building! The professional team at Saunders Commercial Seismic Retrofit can provide a thorough and multi-faceted inspection of any commercial building.  In addition, Saunders Seismic Commercial Retrofit is highly experienced in anchoring commercial properties and removing potential hazards to ensure the safety of building occupants, machinery and inventory.

If you have questions about earthquake retrofitting or want to know more about when is the best time to protect buildings in the Bay Area from earthquake damage, call the experts at Saunders Commercial Seismic Retrofit today!

 

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(408) 267-3876

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