Alaska seismometer records northern lights

Aurora near Poker Flat, Alaska. Credit: Aaron Lozevsky, Fairbanks Aurora Tours

Aaron Lozewski, who leads the Aurora sightseeing tour in Alaska, was fortunate enough to have a picture of an “explosion” of brilliant pink light in a night sky in February.

A disturbance similar to Earth’s magnetic field, which lit up the sky for Lozewski’s camera, was captured by a seismometer on the ground, a team of researchers reported in the magazine Seismic research paper.

By comparing data collected by all of the sky’s cameras, magnetometers, and seismometers during three Aurora events in 2019, seismologist Karl Tape and colleagues from Alaska Fairbanks find that it is possible to match the striking performance of lights with seismic signals is. in different ways.

Researchers have known for some time that seismic is sensitive to magnetic fluctuations — and have worked hard to find ways to shield their devices against magnetic effects or to remove these unwanted signals from their seismic data. But the aurora study provides an example of how a seismometer can be combined with other means to study these fluctuations.

“It can be difficult to be certain that these seismometer recordings are produced with the same effect as moving 120 kilometers up in the sky,” Tape said. “It helps to have a simultaneous view of the sky, to provide more confidence in what you are seeing from the signals at ground level.”

Aurora borealis, or northern lights, occur when solar winds emitted from the surface of the Sun – meet a protective magnetic field surrounded by the Earth. The collision of particles produces colored light in the sky and fluctuations in the magnetic field are sometimes referred to as “solar or space.” A magnetometer positioned on the Earth’s surface is the primary device used to detect these fluctuations, which can significantly affect electrical grids, GPS systems, and other critical infrastructure. The aurora usually appears in winter in high-latitude regions such as Alaska.

The seismometers in the study are part of the USARE Transportable Array, a network of temporary seismometers placed in North America as part of the Earthscope project. The array was completed in the fall of 2017 in Alaska and Western Canada. The Aurora paper is one of several included in an upcoming SRL Focus section about Earthscop in Alaska and Canada.

These temporary seismic stations are not shielded from magnetic fields, unlike more permanent stations that often hang in mu-metal, a nickel-iron alloy that directs the magnetic field around the device’s sensors. As a result, “I was blown away by how well you can record magnetic storms across the array,” said US Geological Survey oceanographer Adam Ringler, a co-author on the SRL paper.

Last month, Ringler and his colleagues published a paper detailing how the array’s 200-plus seismometers in Alaska could be used to record space weather, potentially 13 magnetometers in operation in the state Enhances

With all-sky camera data, seismic array data can help to make sense of the strong changes in the magnetic field that occur in the magnetic east – west direction, adding another dimension to the north-south directional study of Aurora and others. Magnetic storm, Tape and colleagues suggest.

The researchers noted in their paper that the link between the aurora borealis and magnetic disturbances was first discovered in Sweden in 1741, and a seismic kilometer in Germany marked the first time an atmosphere-created magnetic event occurred during a strong solar storm in 1994. figured out.

“People have been making these connections for 250 years,” the tape said. “This suggests that we can still search, in this case with earthquakes, to understand the aurora.”

Northern Lights, aka ‘Aurora Borealis,’ may come to you in a sky this week

more information:
Aurora recording on a seismometer at Karl Tape et al, Alaska, Seismic research paper (2020). DOI: 10.1785 / 0220200161

Provided by the Seismological Society of America

Quotes: Alaska’s seismometer recorded northern lights (2020, July 29) from July 29, 2020

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