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Many have lost loved ones, or are otherwise affected by the COVID-19 pandemic, despite lockdown measures. A byproduct of these unprecedented measures has been a global reduction in seismic noise; our study on this is just published in @ScienceMagazine https://science.sciencemag.org/lookup/doi/10.1126/science.abd2438 (OA)
We had a unique collaboration between 76 coauthors from 66 institutions in 27 countries. @seismotom (“the science catalyst”) began this work by openly sharing his noise codes & gathering a wonderful community. We’d now like to show & walk you through our results …
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As the team processed+analysed open seismic data from permanent monitoring networks & citizen science stations (e.g. @raspishake) we rapidly developed a global noise dataset. We found noise reductions at 185 stations in 77 countries - mostly in urban areas; some in remote areas.
Here is how this looks globally; from the seismic noise reductions you can see the lockdown noise reduction “wave” starting in China, then spreading to Italy & beyond. It even eclipses the annual end-of-year holiday noise reduction.
Let’s look at some examples ...
Let’s look at some examples ...
In China, lockdown/quarantine measures started at Chinese New Year (normally a quiet period). In 2020 the noise level drops much lower & for much longer. This is especially stark in Hubei province. In Beijing in May, the noise level still hadn’t recovered to pre-pandemic levels.
In Sri Lanka, we saw a massive “cliff-edge” plummet in seismic noise after lockdown. Barbados, too; here the noise level dropped before a local curfew. Correlating with flight data from the int’l airport (by @simon_sat) shows this noise level dropped due to tourists repatriating.
In New Zealand, on islands not directly connected to populated areas, we saw the seismic lockdown effects on sensors buried hundreds of metres below the ground in boreholes. These sensors are installed at depth to get away from human-generated noise.
Seismometers installed inside universities and schools ( @weston_quakes & @wmvanstone) showed that noise levels during lockdown were even 20% lower than those during school holidays, showing that seismometers record noise from the wider environment - not just v. localised effects.
Seismologists are often most interested in natural sources (e.g. earthquakes, volcanoes), but everyday human activity – e.g. walking, driving, train travel, construction/industry - causes a "buzz" that contaminates & potentially masks these signals. This changes during lockdowns.
We found the seismic noise level globally dropped by ~50% in March-May 2020. The seismic data correlate with mobility data (e.g. Google/Apple) showing that real-time seismology can be used to assess broad changes in human behaviour & lockdown dynamics, & without privacy issues.
We can use this unique window to find signals from natural sources that might've been previously concealed – hinted by this example from Mexico. A better understanding of human noise may improve natural hazard monitoring & may even be used to image Earth as “virtual earthquakes”
There is loads more cool science to do with a huge amount of data to analyse in this pretty new field of seismology. We invite further studies on this subject for a special issue in the @EuroGeosciences @EGU_SEarth journal https://www.solid-earth.net/special_issues/schedule.html
Thanks so much to our fabulous coauthors who have worked so hard on this and been a pleasure to work with: @seismotom @seismo_steve @Koen_VanNoten @seismo_koel @Raphael_DePlaen @ZAMG_AT @jdassink @flaviocannavo @sebacarquake @CoCaudron @SeisCROv @seismodave @dias_geophysics, ...
@OlivierdenOuden @JDiazCusi @lasloevers @tonino013 @stevenjgibbons @GironaTarsilo @marcopovitch @SeismoAnna @jess_irving @jamalreyhani @buyukakpinar_p @Weston_Quakes @celestelabedz @wombatpretense @vh_marquez @f_massin @mikamckinnon @obspy @MeghanSMiller @LouisMoresi
@paleosurface @seismoyogi @laviedej @simon_sat @jpulli @retailleauLise @claudiodsf @shaharkadmiel @Stott_Alex @SubediShiba1 @BerkeleySeismo @mar_tapia @fthturhan @vdpluijm @wmvanstone @jerome_vergne @Geenimetsuri @HanXiao15682256 @Seismologie_be & many more not on Twitter
Finally, a big thanks to the technicians & operators of seismic networks worldwide who continue to go to great efforts in maintaining their seismic stations & sending open data in real-time - especially during the current tough times (so many - see the paper for the full credit)
