A "deep creep" motion near San Andreas, the San Jacinto faults explain the unusual California earthquakes

Scientists have discovered a strange movement beneath the surface of the Earth, near the largest fault lines in California.

Geoscientists who have analyzed thousands of small earthquakes near the San Bernardino basin near the San Andreas and San Jacinto faults in California have discovered a strange and unexpected type of motion 10 km below the surface of the Earth.

Researchers believe that the movement, known as "deep creep", could be the source of unusual seismic formations recorded in the region over the past 36 years.

Jennifer Beyer and Michele Cooke, of the University of Massachusetts at Amherst, have developed a 3D model based on readings from thousands of small earthquakes in the hope that the new model can help experts better predict where and how when the next major earthquake could occur.

California is thought to be late for a particularly strong earthquake called the "Big One," which makes earthquake prediction important.

The data showed that many deep earthquakes have a different deformation style than other deformations in the region. The breaks showed a vertical movement instead of the expected horizontal slip.

The modeling revealed that vertical movement can be produced in the basin of the northern part of the San Jacinto Fault, which moves backwards instead of remaining stuck like the San Andreas Fault.

"This basin was an extension of these models, unlike the surrounding areas of waste," Cooke said in a press release issued by the University of Massachusetts at Amherst.

"The extension was limited inside the basin just like the configuration of abnormal earthquakes. This gave me an idea of ​​what maybe these faults were not blocked as they should be between large earthquakes, but at depths less than 10 km, they crawled.

Scientists generally use GPS to study creep in faults, but this does not work in this case because the San Jacinto and San Andreas faults are too close to each other. The researchers explained that this is why no one had seen the "deep creep" before; the traditional method used to detect it does not work.

In their article, which was published in the Geophysical Research Letter On August 30, the researchers explained that small earthquakes occurring between faults may have a different deformation style than large earthquakes generated along active faults.

According to Beyer and Cooke, this means that scientists should not rely on the information recorded by small earthquakes in the San Bernardino basin to predict the loading of San Jacinto and San Andreas faults nearby.