Scientists identified a signal suggesting that the magnetic field was changing between 72 and 24 hours before earthquakes.
Using magnetometers to detect faint signals, scientists may be able to improve our understanding of what happens before earthquakes and improve early earthquake detection. Researchers studying intermediate to large earthquakes in California discovered that the local magnetic field changes two to three days before the quake. Seismologists hope their technique can be refined to eventually help forecast earthquakes since experts have found a faint but statistically significant signal of the magnetic field changing. According to Dan Schneider, director of Stellar Solutions’ QuakeFinder, an earthquake research department, it’s a modest signal.
The Changes don’t occur every time
Despite its intriguing nature, Schneider, a co-author of the study, does not claim that it exists before every earthquake. There has long been a debate about whether or not the magnetic field shifts before earthquakes. Despite decades of studies, the U.S. Geological Survey says there is no convincing evidence that earthquakes are preceded by electromagnetic phenomena. Using magnetometers at 125 sensor stations along major California faults, the scientists collaborated with the Google Accelerated Science team. 19 earthquakes with a magnitude of 4.5 or greater occurred along the faults between 2005 and 2019. The multistation analysis took other factors into account, such as rush hour traffic, that might affect the magnetometers but have no relationship to earthquakes.
Solid data and more research
The biggest challenge for interpreting these data is distinguishing this kind of noise from earthquake-related signals. They identified a signal suggesting that the magnetic field was changing between 72 and 24 hours before earthquakes based on the data they trained their algorithms on. Future efforts will be aimed at reducing ambient noise from magnetometers by fine-tuning and refining the models. As an example, accounting for solar activity improved the results substantially in this study. To further eliminate solar-induced noise, the team will continue to use data from remote stations. Using further research and isolation, Schneider believes there is a possibility that a forecasting system could be built in the future based on periodic changes in the magnetic field.
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