In a world first, a fleet of giant balloons fitted with a network of seismic sensors has recorded a powerful earthquake from the stratosphere.

Hot air balloons fly over mountains in anticipation of infrasound waves caused by earthquakes. In the figure, these waves are shown as gray dots. Credit: CNES/Rafael Garcia

The event is of particular interest to the scientific community because such a technique could one day be used on Venus, where the hot and dense atmosphere prevents current technology from registering the planet’s tectonic vibrations.

Balloons floating in the stratosphere and special sensors record the infrasound emitted into the atmosphere during earthquakes. The balloons, which are about 11 meters in diameter and weigh 30 kilograms, can accommodate up to four such devices.

Stratostats – a novelty in the field of seismology. However, a flotilla of such aircraft recently recorded a 7.3-magnitude earthquake in Indonesia.

“We are very happy because the earthquake was recorded not by one balloon, but by several simultaneously,” says Rafael García, lead author of the new study and a planetary scientist at the Higher Institute of Aeronautics and Space at the University of Toulouse. .

The above earthquake was recorded on December 14, 2021 by four Stratol-2 balloons launched by IASE. The instruments recorded the infrasound emitted at a distance of more than 3,000 km (1,860 mi) from an altitude of about 20 km (12 mi).

The data obtained helped the researchers to accurately estimate the amplitude, ground motions, source parameters and behavior of the seismic waves.

Next stop: Venus

Although the balloons have only been tested in Earth’s atmosphere so far, scientists consider the study a major leap forward in understanding the tectonic processes in the bowels of Venus.

“Studying strong earthquakes with stratospheric balloons is kind of a competition,” Garcia says. “But it’s good competition because at the end of the day, we’re trying to express the same idea.”

“Our interest in Venus is because we don’t know much about its interior,” Garcia says. “We don’t know how it works internally, and on Earth, seismology is one of the best tools for understanding these processes.”