One of the most recent earthquakes that is forever etched into Los Angelino’s collective memory was the 1994 Northridge earthquake that claimed the lives of nearly 60 people, while injuring 9,000. [viii] The earthquake did extensive damage and registered at a 6.7 magnitude on the Richter scale. Lower and first floor structures in multiple buildings completely collapsed, crushing those unfortunate enough to be trapped inside, due to some of the strongest ground motions ever recorded in an urban setting in North America.
Just a few years earlier, in 1989 the Loma Prieta Earthquake in San Francisco took the lives of 63 people and injured thousands more. It has been touted as the World Series earthquake, because it occurred during the World Series. The damage it created racked up to more than $6 Billion in property damage, after seismologists (earthquake scientists) measured it at 7.1 magnitude on the Richter scale, the largest earthquake to occur on the San Andreas since the 1906 S.F. quake. This also proved to be one of the most expensive natural disasters in US history. [ix]
The largest documented earthquake in California history was the 7.9M Fort Tejon quake in San Luis Obispo County, which occurred January 9, 1857 along the San Andreas from near Parkfield almost to Wrightwood, a distance of close to 200 miles. Often compared to the devastating 1906 San Francisco earthquake, the Fort Tejon quake actually caused larger average and maximum ground movements than the more famous 1906 quake. Horizontal displacement along the fault was as much as 29.5 feet (9 meters). [x]
No list of major earthquakes in California history would be complete without mentioning the “Great Quake of 1906” in San Francisco. Thousands of people (somewhere in the ballpark of 3,000-6,000 people) lost their lives during this nearly 300-mile long rupture that occurred along the San Andreas Fault Line. Additionally, 80% of the city was destroyed by the earthquake and accompanying fire, leaving hundreds of thousands homeless, which makes this comparable to a modern-day Hurricane Katrina with respect to damage.
Legend of “The Big One”
Seismologists have been studying earthquakes in California ever since Karl Grove Gilbert began studying them after the Owens Valley earthquake in 1872. [xi] He discovered faults were a primary feature in causing earthquakes, rather than the farcical notion major underground explosions were the primary culprit. For decades, they were fascinated by what made them so common, and they become obsessed with learning more about what would make them occur. Then in 1906, a “Big One” hit San Francisco, causing massive amounts of damage and destruction. Lives were literally torn apart, and families and business owners were forced to find new ways of continuing in the aftermath.
So, what was the main cause of this so-called Big One, and what made it different than other earthquakes at the time? As we explored previously, the San Andreas Fault line runs all the way through California. The Big One in 1906 released a lot of pressure from the San Andreas, which meant it had a very powerful ability to move, causing massive damage. Additionally, through the study of this, scientists realized the buildup of underground pressure is what causes earthquakes to occur, rather than previous thoughts on the subject. As they began exploring this more, they realized earthquakes along the San Andreas aren’t one-off events. Instead, the pressure under this massive stretch of land is always living on borrowed time.