Natural disasters can be terrifying, and their unpredictability can cost countless lives. Which is why many around the world work hard to prevent, or at least prepare for, those exceptional events.
And that's where a team of researchers from Hendrix College in Conway, Arkansas, come in. They've developed a new early-warning system that can potentially predict different natural disasters by using infrasound – sound waves below what the human ear can hear. Their results are discussed in the Journal of Applied Physics.
The system is still very much in the preliminary phase, but it was able to forecast a tornado appearing half an hour before the funnel hit the ground. That's significantly better than what's usually possible with current instruments, which can only manage around 10 minutes.
It can also provide crucial data about earthquakes, which could lead to better constructions, and can measure volcanic eruptions and hurricanes happening in remote areas that might affect air traffic.
“The detection of infrasound 30 minutes before a tornado is on the ground, in conjunction with Doppler radar, could prove very useful as an early warning system,” said team leader Robert Dunn in a statement. “And the ability to detect the rotational components of earthquake-generated seismic waves may help reduce the damage from earthquakes… because building codes often neglect the effects of ground rotation.”
The system is made of a ringed laser interferometer, where a laser beam is split into two parts, that can detect sources of infrasound that are both atmospheric and geological.
Laser interferometers may not be a household name, but you might have heard of them before in the context of the discovery of gravitational waves. The technology in this research is very similar, but instead of having lasers shot over kilometers, the whole set-up can fit in a large room.
In the ring interferometer, a laser is shot in a cavity where a plasma tube projects it in a clockwise and anti-clockwise direction. It is then recombined into a single light source. That’s where the interference part of the interferometer comes in.
Infrasound can enter the cavity and perturb the laser, creating a different interference pattern, and that pattern can be used to make predictions or establish the properties of natural disasters. It’s clearly early days, but the potential impact of this technology could be huge.