The massive volcanic eruption in Tonga last year was so powerful it disrupted satellites on the other side of the planet. The researchers warn that a similar event could again cause dangerous interference in the future, unless we learn to better predict seismic activity.
The eruption of the Hunga Tonga-Hunga Haʻapai volcano in January 2022 was the the most explosive of the 21st centurycreating tsunamis 90 meters high and throwing ash 57 kilometers into the sky. Atsuki Shinbori at Nagoya University and his colleagues have now shown that it also disrupts satellite communications thousands of miles away.
GPS satellites have long been known to be vulnerable to an effect called equatorial plasma bubbles (EPB). These are areas of low pressure that form and rise like bubbles in the atmosphere. During the day, the sun’s rays ionize the highest part of the atmosphere – a layer called the F region, located between 150 and 800 kilometers above the Earth’s surface. This increases the density of the ionosphere, more at the equator than elsewhere due to the intensity of the sun.
When night falls, these ions recombine and can form EPBs which affect the transmission of radio waves through the atmosphere, which carry GPS signals. Scientists have already discovered that EPBs can also be formed by winds, and researchers have long speculated that they are also formed by volcanic activity.
“We couldn’t definitely link them in the past. Nowadays, many different observational data have become available with the spread of the Internet, so we can perform integrated data analysis,” says Shinbori.
Scientists Noticeable degradation of GPS signals during the Tonga eruption. Shinbori and his colleagues have now analyzed the data to prove a correlation. They used data from the EPB Arase sensing satellite, the Himawari-8 satellite that monitors atmospheric pressure waves, and ground-based ionospheric observations. They found evidence of EPBs in low-latitude equatorial Asia after the arrival of pressure waves generated by the volcanic eruption. Shinbori says better forecasting of volcanic activity is key to mitigating the effects of satellite disruption.