The San Andreas fault is one of the most feared regions for its seismic activity. Although there has not been a major movement in recent years, seismologists believe that it could happen at any time.
The planet has a very complex configuration, it is not only a land mass covered by the sea in some regions, but it has a layered structure, each of which has an important function. As if it were a living being, the Earth has its own ways of releasing energy and thus continues to restructure itself over the eons.
What is a geological fault?
The main layers that make up the Earth are first, its core, which is then covered by the mantle, and finally, the Earth’s crust. Each of these layers is in turn subdivided, and one of the regions closest to the crust is the lithosphere, which is where the tectonic plates live.
The lithosphere is where the mantle and the Earth’s crust meet, so it is composed of solid material that clumps together in the form of tectonic plates. As we know, these are constantly moving under our feet, causing earthquakes.
But some of these movements may be so abrupt or simply that the tension in certain places is such that it ends up breaking the lithosphere. This rupture is called a geological fault, which, in simpler words, is when the Earth’s crust cracks, causing the elevation or sinking of sections of land and generating a boundary between two tectonic plates.
The San Andreas fault
There are faults of different types and sizes; however, one of the most important ones is the San Andreas fault, for being one of the largest of its kind. It crosses from north to south the state of California, United States, and extends towards Baja California in Mexico. It delimits the North American plate from the Pacific tectonic plate.
In total, it extends for 799 miles and is divided into three sections: north, central, and south, with the northern region being the most famous for the 1906 earthquake that had an estimated magnitude of 7.9 and devastated San Francisco. The fault begins in the town of Hollister and runs through at least eight major cities in California and Baja California. San Francisco, Daly City, Palo Alto, Palmdale, Desert Hot Spring, Palm Spring, and Mexicali, the latter in Mexico, are among the cities that tower above the San Andreas fault.
What would happen if the fault collapses?
More than 38 million people live near the fault, so a major earthquake would greatly affect large cities. The fault has already gone through major activity. 160 years ago, the northern part ruptured during the 1857 earthquake that raised the ground to 9 meters. Later in 1906, another earthquake occurred in the central section, which ended in the lives of 3,000 people in the city of San Francisco.
However, the one that currently worries seismologists the most is the southern region, which has not been active for about 300 years and has been accumulating stress for a long time, so they believe it could cause an earthquake at any time. Especially, because, according to research, the periodicity of earthquakes in this region is every 150 years.
According to researchers from the US Geological Survey, who developed a computer model to simulate an earthquake in the southern part of the fault, the next major event could have a magnitude of 7.8. The movement would initiate a rupture near the Salton Sea in California, which would then shoot northward along the entire length of the fault to touch Los Angeles.
The number of victims would amount to more than 50,000 people affected by the movement, hence the great importance of construction regulations and action measures in the event of a disaster of this nature. However, it is not known when such an event could occur, but seismologists are certain that the fault will collapse at some point in history.
Story originally published in Spanish in Ecoosfera
