Biggest Earthquake In Los Angeles: The Natural Disaster!

Earthquakes are not just scary events but can cause damage of severe magnitude.

Los Angeles is one of the most well known cities in California, and unfortunately, witness to some of the worst earthquakes. Researchers say that the probability of a big earthquake hitting Los Angeles is nearly 31 percent.

The last big earthquake to hit Los Angeles had a magnitude of 5.1 on the Richter Scale and took place in the year 2014. Overall, California has a long history of earthquakes, with the first such event being recorded in 1769.

Every year two to three earthquakes of significant measurements occur here. The last earthquake of such kind happened in 2019 and had a magnitude of 6.4, followed by another quake measuring 7.1. These quakes affected Los Angeles as well.

One of the primary reasons why Los Angeles is so prone to earthquakes is due to the presence of several faults in the city, two of which are the Northridge Blind Thrust Fault and the Sierra Madre Fault Zone.

Overall, even in California, a number of faults exist, including the well studied San Andreas Fault. The two most notable earthquakes to have occurred in Los Angeles were the San Fernando Earthquake and the Northridge Earthquake.

The recorded magnitude of both these quakes was similar, but their after effects were not the same.

The Northridge earthquake struck in the year 1994 and has become one of the most well documented disasters due to the complete collapse of the system it caused. However, the San Fernando earthquake, which happened way before the Northridge earthquake, also helped scientists better prepare against such calamities.

To learn more about the biggest earthquake in Los Angeles, keep reading! You can also check out the biggest acorn in the world and the biggest blizzard.

Surprising Facts About Big Earthquakes In Los Angeles

In recent times, the strongest earthquake to have affected Los Angeles was the one that occurred in 1971 in the San Fernando Valley. This earthquake reached a magnitude of XI in the Mercalli Intensity Scale.

It is also essential to note the Northridge Earthquake of 1994 had a magnitude of IX on the same scale.

However, on the Richter Scale, the former measured 6.6, while the latter came in at 6.7. Even though Los Angeles has suffered from a number of major earthquakes, nothing has ever compared to these two events.

In general, the cause of earthquakes is quite simple. The Earth's surface has cracks known as faults.

At times, the rocks beneath the surface of the Earth move, causing movements in quick succession along these faults, causing energy (seismic waves) to suddenly release and shake the ground, hence, resulting in an earthquake. A strong earthquake is generally characterized by considerably strong seismic waves.

What was surprising about the earthquake that occurred in the San Fernando Valley was its cause. While most earthquakes in California are due to strike slip faults, where two plates move next to each other in opposite directions, the San Fernando earthquake was the result of a thrust fault.

In thrust faults, older rocks tend to move on top of younger rocks resulting in a quake. So, the largest earthquake to have occurred in Los Angeles already had unique features about itself.

On the other hand, the Northridge earthquake struck the Los Angeles area due to a blind thrust earthquake. Blind thrust earthquakes are difficult to ascertain as such quakes occur along with the type of thrust fault that does not show up on geological mapping due to being invisible on the surface of the Earth.

This major earthquake led geologists to identify and name the fault line along which the quake took place. The name of this fault line was given as Northridge Blind Thrust Fault.

Interestingly, while the United States Geological Survey initially thought that the quake took place in Northridge, a well-known region within the San Fernando Valley, they later realized the actual center of the quake was a place called Reseda, also located in the same area. However, the name 1994 Northridge earthquake struck.

Uncanny Facts About Big Earthquakes In Los Angeles

While both these earthquakes were centered within Los Angeles of Southern California, their effects were felt far and wide in almost every direction. Let us now learn about how these earthquakes affected much of California.

The San Fernando earthquake occurred during the early hours of February 9, 1971. Having a moment magnitude of 6.6, it lasted for 12 seconds.

The most damage occurred in the north of the San Fernando Valley. In addition to that, a shaking of high magnitude occurred at the foothill region of the San Gabriel Mountains.

This quake had a depth of 5.6 mi (9 km) and spread to the states of Arizona and Nevada, in addition to being felt throughout much of California. However, what was even more shocking was the aftershock from this San Fernando earthquake.

Over the next 30 days, the United States Geological Survey recorded aftershocks that had a magnitude of four or sometimes even higher. There were more than 200 incidents of such aftershocks.

In general, aftershocks occur after earthquakes as the faults keep transferring energy in a series. Therefore, naturally, a bigger earthquake amounts to bigger aftershocks that are more in number.

Coming to the Northridge earthquake that occurred on January 17, 1994, the entire quake lasted for 10-20 seconds and had a depth of 11.3 mi (18.2 km). This quake was more prominently felt in the West San Fernando Valley of Southern California.

Apart from the Valley, much of the Greater Los Angeles Area was affected. These areas included Simi Valley, Hollywood, Santa Monica, and Santa Clarita.

Even San Diego and Las Vegas were affected. Anaheim, a city in Orange County of Southern California, also sustained damages due to the earthquake.

One of the reasons why the Northridge region of Southern California is highly susceptible to severe earthquakes is because of the nature of its faults. While these faults move slowly when compared to the San Andreas Fault, another one of the active faults of California, they do tend to produce more earthquakes.

Destructive Facts About Big Earthquakes In Los Angeles

Needless to say, each of these earthquakes left behind a massive trail of disaster that took months or even years to undo.

While both these quakes had a similar magnitude on the Richter Scale, the Northridge earthquake did cause more damage than the San Fernando earthquake.

According to information shared by the United States Geological Survey, this was primarily due to the fact that the Northridge earthquake hit the San Fernando Valley, which had a greater population, while the San Fernando earthquake occurred mainly in the region of the San Gabriel mountains, a remote location with less people.

The aftermath of this devastating San Fernando earthquake in Southern California was highly concerning. One of the most troublesome issues to have occurred following this quake was the heavy damages sustained by some of the hospitals and medical care centers.

The Veterans Hospital and Olive View Medical Center both had significant damages to their buildings.

In addition to this, while some freeways fully collapsed, there was a partial collapse in others.

Fortunately, the school buildings of the affected areas sustained little damage, as their building codes were upgraded following the earthquake at Long Beach in 1933. All this and more property damage in different areas led to the death of 65 people, in addition to the financial loss of 505 million dollars.

The Northridge Earthquake is often tagged as one the costliest disasters to have occurred in the United States. This is because the financial losses sustained due to this earthquake were humongous, accounting for an estimated 20 billion dollars in terms of damages and around 49 billion dollars in terms of total financial loss.

The toll on human life was also immense. While there were 57 recorded deaths, 9,000 people sustained injuries, and over 100,000 people became homeless due to the mass destruction of buildings.

Even much of the transportation in the area came to a halt as a lot of the freeways were completely or nearly destroyed.

There were also fire hazards due to ruptured gas lines. Needless to say, Southern California had never witnessed a calamity of this level.

However, the Northridge earthquake did lead to scientists and researchers adopting better levels of preparedness for such an earthquake in the future. Being one of the most studied earthquakes in not only Southern California but the whole of North America, this earthquake also let researchers get a better idea about how blind thrust earthquakes work.

Additionally, researchers got to identify the notorious Northridge Blind Thrust Fault, which caused this earthquake of an astronomical magnitude and study its differences with the San Andreas fault.

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