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Caltech Grad Student: Earth is Moving Less After “Safer at Home” Order

Published on Monday, April 6, 2020 | 4:22 am
Caltech graduate student Celeste Labedz. Photo courtesy Caltech

A graduate student in geophysics at Caltech has confirmed Earth is actually moving less as a result of many human activities being shut down due to the COVID-19 global pandemic.

Caltech graduate student Celeste Labedz points to “falling seismic background noise” in a story published by the research journal Nature on March 31 and discusses how the coronavirus pandemic has brought chaos to lives and economies around the world, but has also meant that Earth is moving a little less.

“Researchers who study Earth’s movement are reporting a drop in seismic noise – the hum hum of vibrations in the planet’s crust – that could be the result of transport networks and other human activities being shut down,” the article, written by Elizabeth Gibney, read. “They say this could allow detectors to spot smaller earthquakes and boost efforts to monitor volcanic activity and other seismic events.”

The article then quotes Caltech’s Labedz who tweeted on March 27 that “a similar fall in seismic background noise” had been registered by a station in Los Angeles.

“The drop is seriously wild,” Labedz said.

Labedz is working for a geophysics masters and is doing research at Caltech’s Seismological Laboratory. She obtained her BS in Physics and Geology from the University of Nebraska Lincoln in 2016.

“My research explores environmental processes using seismological observations,” Labedz says in her profile on Caltech’s seismology lab webpage. “In particular, I am currently investigating subglacial hydrologic conditions using continuous seismic tremor data collected on and around the glacier. I aim to characterize the presence, pressure, and sediment load of subglacial water flow in order to improve observations and understanding of glacier dynamics as a whole. I am also interested in geoscience communication and public outreach.”

The Nature article also cited work by Thomas Lecocq, a seismologist at the Royal Observatory of Belgium in Brussels, where the drop in seismic vibrations has been observed.

Lecocq said a noise reduction of this magnitude is usually only experienced briefly around Christmas, when most families around the world also stay at home.

Seismic vibrations are not only caused by natural events such as earthquakes, but by man-made activities as well, including moving vehicles and industrial machinery, the article said.

Andy Frassetto, a seismologist at the Incorporated Research Institutions for Seismology in Washington DC, is quoted as saying that if lockdowns continue in the coming months, city-based detectors around the world might be better than usual at detecting the locations of earthquake aftershocks.

“You’ll get a signal with less noise on top, allowing you to squeeze a little more information out of those events,” Frasetto told Nature.

The article said the reduction in seismic background noise is expected to be beneficial to seismologists who use naturally occurring background vibrations to probe Earth’s crust, because it would boost the sensitivity of detectors to natural waves at similar frequencies.

“There’s a big chance indeed it could lead to better measurements,” Lecocq said in the report.

Emily Wolin, a geologist at the U.S. Geological Survey in Albuquerque, New Mexico, said many stations are purposefully located in remote areas or deep boreholes to avoid human noise. Their measurements on the drop in seismic noise may not be as pronounced as those observed in Brussels, she was quoted as saying.

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