23 de January de 2025
In May 2024, the most powerful solar storm in 35 years left a remarkable imprint on seismic data collected across the globe. A new study led by Jordi Díaz Cusi, a seismologist at Geosciences Barcelona from the Spanish National Research Council (GEO3BCN-CSIC), has shown that magnetic signals were clearly detected for over 55 hours.
The research, published in Scientific Reports, highlights that this was one of the longest geomagnetic storms ever documented by seismometers. “Measurements from many broadband seismometers deployed around the world were impacted by the interference caused by this major solar storm,” explains Díaz.
Between May 10 and May 13, solar particles bombarded Earth, triggering a geomagnetic storm of G5 intensity — the highest on the scale. These events, in addition to producing stunning auroras, can disrupt power grids, satellites, navigation systems, and even impact migratory animals.
The study delves into how electric currents induced by changes in the Earth’s magnetic field influence seismic sensors. These disturbances are detected at frequencies below 10 mHz, particularly between 1.5 and 5 mHz, a range classified as Pc5 magnetic pulsations.
A new tool for geomagnetic research
While magnetometers are traditionally used to monitor Earth’s magnetic field, Díaz’s work underscores the potential of broadband seismometers as complementary instruments. Thanks to their global distribution, seismometers provide a much broader coverage and deliver detailed records of different phases of such events. During the May storm, for instance, over 300 seismic records were collected across Europe, compared to just 30 magnetograms.
“Sudden variations in the magnetic field disrupt low-frequency seismic vibration recordings, which is why some seismic stations attempt to shield themselves from magnetic interference,” says Díaz. “However, this interference can be repurposed as an opportunity to study the evolution of solar storms and their effects on Earth in greater detail.”
For this analysis, Díaz’s team utilized seismic data from platforms such as EIDA-EPOS (European Integrated Data Archive for EPOS) and the FDSN (International Federation of Digital Seismograph Networks). This approach allowed them to identify patterns in magnetic signals captured by European seismometers and major global seismic networks.
“Seismometers capture the temporal variation of the magnetic field in fine detail, but they may be affected by local factors that alter the amplitude or polarity of the signals,” notes Díaz. He adds that “while they cannot fully replace magnetometer readings, seismic signals can significantly enhance our understanding of solar storm evolution over time,” especially since the number of operational seismometers worldwide far exceeds that of magnetometers.
Findings like these could revolutionize how solar storms are monitored, establishing seismometers as essential tools for observing space weather and its impacts on our planet.
Reference
Díaz, J. Monitoring May 2024 solar and geomagnetic storm using broadband seismometers. Sci Rep 14, 30066 (2024). https://doi.org/10.1038/s41598-024-81079-6