Even high above the Earth’s surface, in the ionosphere which constitutes the border between the atmosphere and space, the effects of earthquakes are significant. For the first time, an international research team has mapped in 3D how the ionospheric electron density fluctuations caused by an earthquake evolved. The results contribute to promoting understanding of the interaction between earthquakes and the space environment.
The joint research team analyzed high-altitude data generated immediately after the Noto Peninsula Earthquake, which occurred on January 1, 2024.
The study was conducted by researchers from Japan’s National Institute of Information and Communications Technology (NICT) and partners based on data from Japan’s ultra-dense GNSS (Global Navigation Satellite System) network. GNSS is a term covering the various satellite navigation systems such a USA’s GPS and others.
Vertical information included for the first time
With the proliferation of GNSS receiver networks, it has become possible to capture ionospheric variations near 300 km altitude in two-dimensional maps. In recent years, several impacts of earthquakes, volcanoes, and weather phenomena on the ionosphere have been revealed. However, conventional observation techniques using these 2D maps have not been able to provide vertical direction information of the ionosphere. As a result, there have been limitations in understanding the three-dimensional structure and the development process of disturbances in detail.
The visualizations show how a three-dimensional wavefront of ionospheric plasma formed around the epicenter of the earthquake. Further, they clarify the temporal changes.
The study is important for the understanding of the interaction between earthquakes and the space environment and will also contribute to enabling more precise ionospheric monitoring.
Data from more than 3,000 receivers
The researchers applied their newly developed 3D ionospheric tomography technique to the data from approximately 1,300 stations of the Geospatial Information Authority of Japan’s GEONET and more than 3,000 GNSS receivers from SoftBank Corp.
Besides researchers from NICT, colleagues from Nagoya University for Space-Earth Environmental Research, the University of Oslo Faculty of Mathematics and Natural Sciences (Norway), and the Kyoto University Institute for Integrated Cell-Material Sciences were part of the team.
Source: “High-Precision 3D Visualization of Ionospheric Variations After Earthquakes”, Topics, NICT.
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