Rapid facts about the San Andreas Fault
How many faults are there at San Andreas? Approximately 746 miles (1,200 kilometers)
What was the biggest earthquake at the San Andreas Fault? The 1906 San Francisco earthquake.
When was the San Andreas fault discovered? 1895
The San Andreas Fault is California’s longest and most famous fault. In this fracture zone, two plates of the Earth’s crust move towards each other. It extends from the Salton Sea in Southern California to the coast off Mendocino in Northern California. On the inland side of the fault, North American plates move southeast. The Pacific Board creeps northwest towards the coast.
San Andreas can create a large destructive earthquake. Earthquakes are measured in magnitude on a scale starting from zero. On this scale, each integer represents an earthquake of 10 times the previous earthquake. Most earthquakes at magnitude 2.5 are not felt, but earthquakes of 2.5-5.4 magnitude usually cause some shaking, but not much damage. Earthquakes with a magnitude of 5.5 have caused damage to the building, with earthquakes above 7.0 being considered the main.
In 1906, the northern part of the fault shaking San Francisco and the Bay Area in a 7.9 magnitude earthquake. This caused a catastrophic fire in the city, killing more than 3,000 people. In 1857, the southern part of the fault shaking, creating a tremor that was thought to be equally large. Only two people died because California had a small population at the time. Geologists warn that San Andreas will cause another major earthquake. When is the only problem?
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5 Fast Facts About the San Andreas Fault
Over the past 3 million years, the San Andreas Fault has traveled an average of 2 inches (56 mm) per year. If that rate continues, Los Angeles and San Francisco will become neighbors in 15 million years. The San Andreas Fault was discovered 11 years before the 1906 earthquake by Andrew Lawson, a geologist who worked at the University of California, Berkeley.
Everything you need to know about the San Andreas fault
What kind of obstacles are the San Andreas faults?
The San Andreas Fault is a “unslip fault on the right side.” This is a complicated way to say that if you are standing on the North American plate side of a fault facing the Pacific Ocean, the Pacific plate side of the fault moves slowly to the right. In San Andreas, the two plates are like blocks that pass each other and sometimes get stuck on the way. When they stagnate – immediately! – The result is a sudden earthquake.
The failure is divided into three segments. The southern segment begins northeast of San Diego at Bombay Beach, California, and continues north to Parkfield, California, near the central state. Earthquakes in this segment will threaten the populous city of Los Angeles.
The central section of San Andreas is known as the “creeping section.” It spreads between the city of Parkfield in California and Hollister in Central California. Here, the obstacle either “creeps up” or moves slowly without causing shaking. Although there have been no major earthquakes in this section of recorded history, scientists believe there may have been an earthquake at some point in the last 3 million years.
Finally, the northern part of San Andreas extends from Hollister to a special place called the “Triple Junction” off the coast of Mendocino. Triple junctions are where North American tectonic plates, Pacific plates, and submarine Gouda plates meet. At this junction, the way plates pass each other on the San Andreas fault changes to a different kind of geology known as subduction zones. In the subduction zone, the Pacific plate slides beneath the North American plate rather than beside it.
How many faults are there at San Andreas?
The San Andreas Fault is approximately 746 miles (1,200 km) long and approximately 10 miles (16 km) deep. San Andreas is a huge drawback that can also be seen from space, but when you zoom in, you’ll see a network of many obstacles from San Andreas.
As such, the entire region is more commonly known as the San Andreas Fault Zone. The area includes faults like the Hayward Fault that runs through the East Bay Area. These secondary faults can cause their own serious earthquakes. For example, in 1868, the Hayward fault was brought to life in a magnitude 6.8 earthquake that killed 30 people. A similar earthquake today will affect the Bay Area, where millions of people live.
How did San Andreas Disorder form?
In the past, tectonic plates beneath the Pacific Ocean directly collided with tectonic plates carrying the North American continent. Below the continental plate is a pattern called a pigeon or subduction. Meanwhile, in the middle of the ocean there was a place where molten lava, or magma, rose from inside the Earth to form a brand new crust.
Where the new crust formed was not far from the subduction zone where the crust was pushed back to Earth. About 30 million years ago, these two spots came together. Where the new crust formed was pushed just below North America!
This was a major change in how geology works in everything in western North America. A new ocean plate touched North America. It moved in a slightly different direction and did not jump just below the continent. The sinking ended and a new strike slip disorder (San Andreas) was formed.
How dangerous is the San Andreas fault?
The San Andreas Fault passes through many more populous areas, including Los Angeles and the San Francisco Bay Area. Scientists consider it a very dangerous flaw, as it can cause damage earthquakes.
Geologists estimate that Southern San Andreas can produce earthquakes up to 8.3 magnitude. To their knowledge, the obstacles have never produced a larger earthquake than the 1857 or 1906 earthquake. Both were probably around 7.9 magnitudes.
But it’s a lot of destructive. 63 people were killed in the 1989 magnitude 6.9 Loma Prieta earthquake that struck the Bay Area. And remember that the magnitude of the earthquake increases by 10 for each integer, so the magnitude of 8.3 is more than 25 times larger than the trembling of the Roma Prieta.
If a magnitude 7.8 earthquake hits South San Andreas, geologists expect it to cause 1,800 deaths, 50,000 injuries and $200 billion in damages.
Can scientists predict the next major earthquake on the San Andreas fault?
Scientists cannot predict when the next San Andreas earthquake or earthquake will occur. However, they can get ideas of future risks by looking at the frequency of earthquakes in the past. In the southern part of San Andreas, some sections appear to have good shaking every 100 years, while others can take up to 300 years between major shivers. The Fort Tehong area, approximately 70 miles (113 km) north of Los Angeles, typically shows great tremors every 100 to 150 years. It was in 1857 when it last hit a major earthquake, so the area is considered to be delayed.
The average time of an earthquake depends on the fault or fault section. They are not always the same. They can change over years or decades. Additionally, dangerous earthquakes can occur at faults on the sides that scientists don’t know about. The magnitude 6.7 Northridge earthquake that struck Los Angeles in 1994 was previously a disruption. The obstacle was not part of San Andreas, but it was a nearby fault affected by San Andreas’ movement.
A US geological survey that tracks faults and measures earthquakes calculated that by 2043 there was a 72% chance of a 6.7 earthquake in the San Francisco Bay area. In the Los Angeles area, there is a 60% chance of shaking over 6.7 over that time frame.
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