The study, ‘Spectral Characteristics of Ionospheric Disturbances Over the Southwestern Pacific From the 15 January 2022 Tonga Eruption and Tsunami,’ explores how evidence from the ionosphere explains why the tsunami grew larger and travelled faster than tsunami forecasts predicted. Due to tsunamis being an extremely rare natural disaster, current tsunami warning systems are far from optimised and rely on a limited number of tide gauges and ocean sensors. In order to advance forecasting, the study focused on using GPS signals travelling through the upper atmosphere to track events on the ground. For example, a large earthquake or volcanic eruption generates pressure waves in the atmosphere. As they pass through the zone known as the ionosphere – around 50 to 400 miles altitude and where electrons and ions float freely – particles are disturbed. GPS satellites sending coordinates down to Earth transmit a slightly modified radio signal that monitors the disturbance.
