The Hunga Tonga eruption has been venting lava for several days and delivered a powerful blast on January 15 that was recorded by seismic stations worldwide. It triggered a massive tsunami that struck multiple islands and alarmed many regions. The extraordinary shock wave sent disturbances across the globe, highlighting how crucial rapid and accurate warnings are for natural disasters.
In a tsunami, every second matters. Yet early warning systems are still inadequate in many places. Over the past century, sixty-something tsunamis have claimed tens of thousands of lives, underscoring the deadly risk these events pose compared with other natural hazards.
As climate change intensifies, these events are expected to occur more frequently. UNESCO emphasizes that being prepared to face such phenomena can be a matter of life and death.
Early warning systems for tsunamis rely on networks of seismometers and sea level gauges that stream data in real time to national and regional warning centers.
The Spanish system includes a national tsunami warning framework built on the National Seismic Network SINAM, Puertos del Estado’s REDMAR tide gauge network, the oceanography institute’s detection systems, and other public administration marine monitoring networks.
Satellite network errors
Even with an established network, gaps remain. Scientists continue to search for ways to enhance early warning of these disasters.
The Tonga eruption offers insights, as atmospheric pressure changes caused by shock waves can affect the ionosphere and disrupt GPS satellite networks.
With this information, a team from Nagoya University in Japan proposed a formula to help design better early warning systems for similar events in the future.
This research appears in Earth, Planets and Space. During a tsunami, atmospheric deformations and oscillations can alter ionospheric electrons, a layer found roughly 80 to 400 kilometers above the Earth.
The researchers examined malfunctions in satellite and radar networks during the Pacific surge. Shock waves traveled as far as Australia and Japan, causing disturbances in the ionosphere that produced strong electric fields and telecom faults.
altered electrons
Remarkably, the ionospheric electrons began changing long before the initial shock wave formed.
Specifically, an electromagnetic disturbance is described as creating ionospheric disorder three hours before the eruption’s seismic tsunami event in Japan, according to Atsuki Shinbori, a coauthor of the study.
In fact, even though Japan and Australia lie in different hemispheres, ionospheric changes occurred almost simultaneously.
The speed difference is crucial. The study notes that electromagnetic waves move at about 1,000 kilometers per second, while the air pressure shock travels at roughly 315 meters per second.
These findings point toward practical applications. Statistical analysis of ionospheric disturbances during volcanic eruptions, combined with seismic data, could help estimate the height and magnitude of tsunamis. Shinbori describes ionospheric disturbances as a new step forward in tsunami forecasting.
Reference report: Earth, Planets and Space, 2022.