A few days before large earthquakes in California, detectable changes in the Earth's magnetic field can be noticed.
According to a report published in the journal JCR Solid Earth, scientists may detect a large shift in the magnetic field two to three days before an earthquake.
This was calculated using data from 19 earthquakes in California.
Earthquakes Along San Andreas Linked With Shifts in Earth's Magnetic Field
Dan Schneider, director of Stellar Solutions' QuakeFinder, an earthquake research division, and co-author of the article, told EOS: "We are not asserting that this signal appears before every earthquake, but it is fascinating," as per Newsweek.
Earthquakes are triggered by the abrupt movement of tectonic plates against one another, releasing massive quantities of energy as seismic waves through the Earth.
Earthquakes may be extremely devastating, resulting in numerous casualties due to collapsed structures.
Knowing when an earthquake is likely to strike would be extremely useful since it would give some time for evacuations from particularly vulnerable places.
However, there has been no accurate technique to anticipate when or where an earthquake will occur, other than the fact that they are more common near tectonic fault lines.
The authors used rigorous machine learning techniques and statistics to explore many earthquakes and a vast amount of data, rather than selectively picking and choosing, according to Roland Burgmann, an earth and planetary Science professor at the University of California, Berkeley, in an interview with Newsweek.
Having some notice of an impending earthquake is especially important in California, which is located on the San Andreas fault line that connects the Pacific and North American tectonic plates.
"Depending on the nature of the warning, it might potentially save hundreds, if not thousands of lives," said David D. Oglesby, a geophysics professor at the University of California, Riverside.
"A very large earthquake on the San Andreas in Southern California, for example, could be devastating, causing possibly over a thousand immediate deaths, isolating the Los Angeles Area from the rest of the country, and having long-term effects nationwide."
A warning two to three days in advance would allow ample time to implement numerous safety measures.
Of course, thorough preparation of people and infrastructure ahead of time is critical for a warning to be successful; extremely detailed preparations for what to do in advance, with a system to carry them out, would be required.
While these magnetic field fluctuations represent a huge step forward, Burgmann cautioned that they are not a reliable prediction of an impending earthquake.
Barbara Romanowicz, a professor of the Graduate School at the University of California, Berkeley, agreed that there could be some magnetically detectable changes in rock properties before an earthquake, but even if some of the observations are valid, this does not mean that they can be used to predict earthquakes.
She told Newsweek that for it to be effective, it would have to be trustworthy, which means being able to distinguish the precursory signal among myriads of other causes for "magnetic changes" that have nothing to do with earthquakes.
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What exactly is the San Andreas Fault?
The Pacific Plate and the North American Plate are separated by the San Andreas Fault. From Cape Mendocino to the Mexican border, it divides California in half, as per Geology.com.
The Pacific Plate includes San Diego, Los Angeles, and Big Sur.
The North American Plate includes San Francisco, Sacramento, and the Sierra Nevada.
Moreover, despite the city's famed 1906 earthquake, the San Andreas Fault does not run through it.
Communities like Desert Hot Springs, San Bernardino, Wrightwood, Palmdale, Gorman, Frazier Park, Daly City, Point Reyes Station, and Bodega Bay, on the other hand, are directly on the fault and hence vulnerable.
The San Andreas Fault is classified as a transform fault. Consider placing two slices of pizza on the table and moving them past each other along a shared straight edge.
Pepperoni crumbles from one side across the border onto the anchovy side. The fault is the same way, and the geology and landforms along the massive rift are exceedingly intricate.
The plates are gradually migrating past one another at a rate of a couple of inches each year, roughly the same as your fingernails grow.
However, this is not a steady motion; rather, it is an average motion. For years, the plates will be stuck together, with no movement as they push against one other.
The built-up strain suddenly cracks the rock along the fault, and the plates drop a few feet at once.
The cracking rock creates waves in all directions, and it is these waves that we experience as earthquakes.
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