Two pieces of Earth's crust grind each other more and more tightly, preparing to 'explode'

New US research shows that the San Andreas Fault - created by two pieces of Earth's crust colliding - poses a far greater threat than we know about it.

According to the Daily Mail, the San Andreas Fault is known for its two stationary and slow-moving parts. Static parts are said to be dangerous parts because they are grinding against each other and slowly building up energy, which can cause giant earthquakes in the future. The slow-moving part, where two tectonic plates find their way to slide over each other, usually releases energy through small vibrations that are less dangerous.

Andreas Fault with the red part being the stationary part, the yellow part being the dynamic part

But new analysis shows that the slow-moving part is also potentially catastrophic.

This slow-moving section lies at the center of an 800-mile-long fault, and the two tectonic plates are now sliding past each other at a steady rate of 26 millimeters per year.

A team led by earthquake geologist Genevieve Coffey from GNS Science in New Zealand took rock samples 2 miles below the surface of this "peaceful" region of motion and found that within just a few hundred years, there have been large earthquakes here, not millions of years ago as previously calculated.

Among them, there are earthquakes up to 7 magnitude. This data is reflected in chemical analyzes that help measure the heat of rocks during past earthquakes.

As such, the bad news is that California may have to get ready for the "Big One," a hypothetical earthquake caused not only by the two stationary parts at the North and South poles, but by all three.

Before that, in 1906, a catastrophic 7.9 magnitude earthquake struck San Francisco, nearly leveling the city in the area north of this fault.

Tectonic plates are the pieces of the Earth's crust. The Earth is estimated to have 15-20 such pieces of crust, constantly sliding over each other. Plate tectonics is vital for the planet to maintain a stable atmosphere and climate that sustain life, but it also causes disturbing geological upheavals such as earthquakes.