Seismographs sensed the Aurora

Researchers have found a link between the readings of the seismograph and the intensity of the auroras in Alaska. During the polar auroras in 2019, which is being watched with the help of magnetometers and all-sky cameras, seismographs simultaneously recorded continuous seismic waves. This regularity may allow to significantly expand the study of the Aurora and the dynamics of the Earth’s magnetic field. Article published in the journal Seismological Research Letters.

Polar light effect colorful glow of the upper atmosphere resulting from the collision of the solar wind with the magnetosphere. Charged particles in the solar wind are redirected and accelerated in the Earth’s magnetic field, reaching the dense layers of the atmosphere close to the magnetic pole regions. There they collide with atoms and molecules in the atmosphere and translate them into an excited state and the relaxation process and is born the light of the Aurora.

Often, instead of exciting the atoms or molecules of the sun’s rays ionize them, which changes the density of charged particles in the atmosphere and leads to a change in its conductivity. In combination with electric fields that frequently occur in the magnetosphere during auroras, this leads to significant currents in the ionosphere. They, in turn, generate a magnetic field, which identifies the researchers auroras as conditionally stable perturbations of Earth’s magnetic field using magnetometers.

These fluctuations of the magnetic field and is sensitive mobile seismographs, which were installed throughout Alaska in 2017. The mobile seismographs, unlike stationary, no magnetic protection. Without ferromagnetic components of the seismographs are too susceptible to magnetic storms, thereby provoking the check of waves, which actually are not connected with seismic activity.

But the flaw in the design of seismographs was on hand scientists who study the Aurora. They are interested in just the magnetic field, however, for such studies in the territory of Alaska established a total of 13 magnetometers against more than 200 seismographs, sensitive to fluctuations in the Earth’s magnetosphere. In addition to observing the night sky, scientists use cameras the entire sky, but in Alaska there are only 6.

Carl Teyp (Carl Tape) of the University of Alaska in Fairbanks have demonstrated that the magnetic-field sensitive seismographs can serve as a tool for observing the Aurora. It turned out that since the installation of new seismographs a strong auroras visible in seismic data as a weak vertical oscillation with a long period in the 40-800 seconds. Thus, the incident polar lights can be seen in not only the magnetometers and all-sky cameras, but in terms of seismographs, however, the precise data of these devices, the authors have yet to obtain.

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