The next California earthquake could be faster than sound and more destructive sciences

A research team from the University of Southern California has warned of a rare and dangerous type of earthquake that could strike California at any time, known as “hypervelocity earthquakes.”

This is a type of earthquake in which the rupture wave moves along the fault at a speed exceeding the speed of the seismic waves themselves, just as happens when an airplane breaks the sound barrier and releases a “bang” into the sky.

Faster than sound

When an earthquake occurs, the entire rock does not break in one moment, but rather a small point begins to move, then the movement gradually spreads along the fault, that is, the separator between two blocks of the earth’s crust. This spread is what is called a rupture wave, and it resembles a small spark that quickly makes its way along the fault line, releasing the energy that we feel in the form of vibrations.

When we say that a high-speed earthquake is “faster than sound,” we do not mean that it is faster than sound in the air. The speed of sound in the air is approximately 340 meters per second, while in rocks, seismic waves travel much faster (it may reach 3000-5000 meters per second).

But what is meant in this context is that the rupture wave is faster than the seismic waves themselves inside the rocks, and this is what makes the vibrations more severe and dangerous because the energy gathers in a “single front,” like a shock wave, in a way that is exactly like crossing the sound barrier in the air.

across the rocks

Earthquake energy is usually transmitted in the form of shock waves that race through rocks and soil, reaching the Earth’s surface, causing the destruction we know. But in high-speed earthquakes, the rupture wave travels faster than the occasional seismic wave, creating something similar to a “seismic shock” that suddenly strikes a wide area, doubling the intensity of the vibrations.

Researchers warn, according to paper A research opinion presented in the journal Seismological Research Letters states that many building and seismic engineering systems in California are not yet designed to confront this type of earthquake, because most current engineering models assume that the earthquake propagates at a constant speed that is less than the speed of the seismic waves.

But if some California faults, such as the famous San Andreas Fault, shift into a high-velocity pattern, the directional forces and lateral vibrations may be more severe than some vital structures, such as bridges, dams, and power plants, can withstand.

Almost certain possibilities

Although scientists cannot predict the date of the next earthquake, statistics indicate that an earthquake with a magnitude of 7 or more will almost certainly occur in California in the coming decades.

Therefore, researchers call for intensifying monitoring of active faults through more accurate networks of measuring devices, in addition to developing digital simulation models that can represent the behavior of high-speed earthquakes.

The study also recommends updating building codes to take into account these unconventional scenarios, so that infrastructure is designed to withstand sudden, directional acceleration waves, not just regular vibrations.