Jakarta –
Some of us must have heard of this the San Andreas fault that divides California, United States of America. Scientists analyze that this fault can produce very large and dangerous earthquakes.
Come on, see information regarding the San Andreas fault which can add to your insight.
Get to know the San Andreas Fault
Quoting from the site Britannica, the San Andreas fault is a large crack in the earth’s crust located in the extreme northwest of North America. It is known, this crack stretches as far as 1,300 km from the northern end of the Gulf of California through Western California, United States and towards the Pacific Ocean near San Francisco.
The tectonic movements that occur along this fault are often associated with large earthquakes that occur on the surface. The earthquakes produced by this fault were the Great San Francisco earthquake in 1906, the 1989 earthquake and the strong earthquake that damaged the suburbs of Los Angeles and Northridge in 1994.
According to plate tectonic theory, it is known that the San Andreas fault represents a transformation boundary (strike slip) between two large plates in the earth’s crust. The two plates are the plates in the south and west of the North Pacific and the north and east of North America.
It is known that the North Pacific plate slides laterally past the North American plate in a northerly direction. Because of its location between two plates, the San Andreas fault is classified as a strike slip fault.
Since the beginning of the 20th century, it is known that the annual movement of plates reaches 4 to 6 cm. However, the movement of the plates from each other is about 1 cm per year during geological time. It is known that during the 1906 earthquake, the top of the fault moved 6.4 meters.
Sections of the San Andreas Fault
Quoting from Live Science, the San Andreas fault consists of three parts. The southernmost portion of the fault moves from the Salton Sea toward Parkfield and California. It turns out that this section has the capacity to generate large earthquakes.
The earthquake caused by this section occurred in 1857, namely the Fort Tejon earthquake with a magnitude of 7.9. It turned out that this earthquake caused the fault to shift up to 9 meters.
The northern part of the fault moves from the city of Hollister through the Bay Area and towards Cape Mendocino, California. This fault is most famous for causing the great San Francisco earthquake in 1906 with an estimated magnitude of 7.9.
Interestingly, the central part of the San Andreas fault, which lies between Parkfield and Hollister, does not produce earthquakes that are recorded as larger than magnitude 6.
Geosciences have excavated fractures and looked for signs of sedimentary layers of ancient earthquakes, but they have not found any major earthquakes in the last 2,000 years that have occurred in this area.
Genevieve Coffey, who is an earthquake geologist at GNS Science in New Zealand, revealed that although the central part of the San Andreas fault does not produce earthquakes, this section can function as a conduit for earthquakes originating from the northern and southern faults.
Threat of the San Andreas Fault
Written in the page IFL ScienceDirector of the Southern California Earthquake Center, Thomas Jordan in 2019 revealed that the San Andreas fault appears to be in a critical state and allows it to generate large earthquakes.
This is because the southern part of the San Andreas plate has not released its massive pressure since 1857. In fact, the fault which forms the border between the two plates must have kept the ever-increasing pressure from the two plates.
The prediction for the magnitude of the earthquake is that it will occur with a maximum strength of about M 8.0 along the system the San Andreas fault with an estimated 7% probability that the event could occur in southern California over the next 30 years.
During the same period it is possible that 75% of earthquakes will occur with a M 7.0. It is known that the energies released by M 7.0, 8.0 and 9.0 are very different. Events with M 9.0 released 32 times more energy than M 8.0 and 1,000 times more than M 7.0.
However, the earthquake with M 7.0 and M 8.0 has also resulted in considerable damage. Although buildings in California are designed to protect them from seismic earthquakes, there is still a risk of damage and they are not 100% safe.
Watch Video “Earthquakes Happen Frequently, Is It Really a Sign of the Apocalypse?“
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