Slight shifts in magnetic field preceded California earthquakes

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Changes in the local magnetic field can be seen a few days before an earthquake. The signal of the magnetic field change is faint but statistically significant, and the seismologists hope their technique can be refined to help forecast earthquakes.

Dan Schneider is the director of the earthquake research department at Stellar Solutions. Schneider, a co-author of the study, said it is very intriguing that the signal exists before every earthquake.

The idea that the magnetic field may change before earthquakes has been debated for a long time. According to the U.S. Geological Survey, there is no evidence to support the idea that earthquakes are caused by interference with the earth's magnetic field.

The magnetic field data from the array of magnetometers at 125 sensor stations was tapped into by the scientists. Nineteen earthquakes of magnitude 4.5 or greater occurred on the faults over the course of a decade.

Rush hour traffic is one of the processes that might affect the magnetometers but have nothing to do with earthquakes. Schneider said that the tallest barrier to interpreting the data was differentiating this kind of noise from potential earthquake - related signals. The researchers were able to identify a signal in the magnetic field between 72 and 24 hours before the earthquake.

Schneider wants to eliminate more ambient noise from the magnetometers. Accounting for the influence of solar activity improved the results. The team will use remote station data to eliminate noise from the sun.

There could be regular changes in the magnetic field that could support the construction of a forecasting system in the future according to the work.

More information: William D. Heavlin et al, Case‐Control Study on a Decade of Ground‐Based Magnetometers in California Reveals Modest Signal 24–72 hr Prior to Earthquakes, Journal of Geophysical Research: Solid Earth (2022). DOI: 10.1029/2022JB024109 Journal information: Journal of Geophysical Research: Solid Earth

The story was re-posted by the Americangeoscience Union. The original story can be read here.