As coronavirus lockdowns quiet the Earth, earthquake scientists get new view

With much of the world shut down due to the novel coronavirus pandemic, scientists who study earthquakes are getting a rare window into the Earth.

“With COVID and people staying at home, the amount of traffic, the amount of trains, helicopters, all of that has really dropped off,” said Natural Resources Canada and University of Victoria earthquake seismologist John Cassidy.

“What we’re finding is that especially in urban areas, what we call ‘background noise’ has dropped dramatically.”

That reduction in background noise means that the incredibly sensitive instruments scientists use to measure quakes, known as seismographs, are able to record extremely small quakes that would have been missed before.

Cassidy said in some cases, the seismographs are now able to record tiny tremors with a negative magnitude.

In some densely populated areas of the world, where isolating seismographs from urban centres is more challenging, such as Europe, Cassidy said that the “seismic noise” has dropped by as much as 50 per cent.

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He said the closest the world usually comes to this level of seismic silence is during major holidays, such as Christmas.

The difference is smaller in B.C., he said, as many of our seismic equipment is positioned on mountain tops or far from highways.

However, he said the increased sensitivity is particularly valuable in B.C. for another reason: it allows a more careful study of volcanic activity.

B.C. lies on the so-called “ring of fire,” a belt of volcanic activity that circles the Pacific Ocean and which is driven by plate tectonics.

“Very tiny earthquakes can tell you something about future volcanic eruptions, as the magma is moving deep in the earth, as we saw at Mount St. Helens about 40 years ago,” said Cassidy.

He said the increased sensitivity could also open the door to new research projects, as scientists observe phenomenon they’ve missed in the past because of background noise.

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