The Fort Tejon earthquake of 1857: The largest known quake in Southern California’s history

California is no stranger to earthquakes. The state experiences an average of 37,000 earthquakes a year, with the earliest known quake being documented in 1769. Despite this, the 1906 San Francisco earthquake was the event that forced the U.S. government to acknowledge the issue. Over the years, California has experienced a number of significant earthquakes, each of which has had a profound impact on the state’s seismic safety codes.

The Fort Tejon Earthquake of 1857

The Fort Tejon earthquake, which occurred on January 9, 1857, is the largest known quake in Southern California’s history. This 7.9 magnitude earthquake ruptured the San Andreas fault for a length of approximately 225 miles between Parkfield and Wrightwood. Despite the severity of the quake, only two deaths were reported due to the collapse of some structures. Parts of the historic Mission San Buenaventura were also damaged and a series of aftershocks were felt for four years.

The Long Beach Earthquake of 1933

The 1933 Long Beach quake, which had a magnitude of 6.4, is one of the most significant earthquakes in world history. It occurred at 5:55 PM on March 10, 1933, causing 120 deaths and an estimated $50 million in property damage. The quake brought attention to the need for building codes that would make structure safer in the event of another earthquake. This led to the passing of the Field Act and the Riley Act, which required buildings to follow safety protocols for earthquakes.

The Sylmar Earthquake of 1971

The Sylmar Earthquake occurred on February 9, 1971 at 6:00 AM with a 6.7 magnitude. The quake affected the San Fernando fault zone and lasted for 12 seconds, resulting in 65 deaths and more than half a billion dollars of property damage. The Olive View Hospital collapse during the quake killed three patients and a hospital worker. This event also highlighted the need for stricter building codes, leading to the passing of the Alquist-Priolo Bill, which required the mapping of active fault zones.

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The Whittier Narrows Earthquake of 1987

The Whittier Narrows earthquake, which had a magnitude of 5.9, occurred on October 1, 1987 at 7:42 AM. The quake caused 123 homes and 1,347 apartments to be destroyed and 513 homes and 2,040 apartments to be damaged. It was also a wakeup call to seismologists and policymakers, leading to the discovery of blind thrust faults.

The Northridge Earthquake of 1994

On January 17, 1994, the Martin Luther King Jr. Day, the heavily populated area of Northridge, California experienced a strong 6.7 magnitude earthquake at 4:30 AM. This earthquake only lasted for 15 seconds, but it caused an estimated $50 billion in damage. 57 people were killed and 9000 were injured. The earthquake also exposed the misconception that steel structures were completely earthquake resistant.


Earthquakes are a way of life in California, and the state has experienced a number of significant earthquakes in its long history. Each of these earthquakes has had a profound impact on the state’s seismic safety codes and has led to the passing of new laws that have improved the safety of buildings in the event of an earthquake. While it’s impossible to predict when the next big earthquake will hit the state, California is better prepared than ever to deal with the aftermath.

How many earthquakes does California experience on average each year?

California experiences an average of 37,000 earthquakes a year.


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