
A reduction in seismic noise is a boon for geoscientists - mmaia
https://www.nature.com/articles/d41586-020-00965-x
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jofer
Not such a great thing if you're doing ambient noise seismology, though! You
win some, you lose some...

(For background, you can also use the noise from trucks/etc as a seismic
source to probe the structure of the subsurface. It's much more
computationally intensive and, well, noisy, but it actually works!)

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TheGallopedHigh
That’s quite interesting. It would be great if you explain a bit more about
it.

Namely, this is only used for locations close roads? Can other natural
occurrences of sound give the same result? Can the same source that’s moving
give a better picture of what’s below by that fact that it’s moving? Ie setup
at different locations, so to speak.

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jofer
Sorry I never noticed this!

More or less any source of noise that's loud enough and is coupled to the
ground works. In fact, a lot of what winds up being a good source is actually
things like ocean waves -- not just man-made noise.

Ideally, you want a clear "spike" of noise at a lot of locations and not
necessarily a moving source. However, something like a truck/train hitting
bumps at different locations along the road could definitely do a nice job of
that.

At any rate, the basic idea is to look at cross correlations of the waveforms
-- any noise that is clearly correlative at different seismic stations is
used.

Take all of this with a grain of salt -- I work in an adjacent field and not
exactly this one.

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Zelphyr
I know almost nothing about seismology or geology so forgive my naiveté here:
Could the lack of movement caused by everybody staying home actually
inadvertently induce greater than normal seismic events?

By that I mean I'm wondering if all of our moving around normally may be like
nano events that cumulatively ease pressure on fault lines? Almost like all of
our movements sort-of force the faults to gently slip all the time instead of
making giant movements, thus releasing an earthquake. But if we're not moving
around much then that pressure starts to build up.

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labster
Oh no, it's World Jump Day all over again. Wikipedia is boring so they deleted
the page, but the Archive has the details (and unlimited free books):

[https://web.archive.org/web/20190221002919/https://en.wikipe...](https://web.archive.org/web/20190221002919/https://en.wikipedia.org/wiki/World_Jump_Day)

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kumarharsh
The XKCD what-if has done some calculations on what would happen if everybody
jumped at the same time: [https://what-if.xkcd.com/8/](https://what-
if.xkcd.com/8/)

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s0rce
Can we use globally distrusted sensitive seismometer data to determine if
lockdowns/shelter-in-place is working? Presumably we should see similiar
decreases. I wonder if the USGS makes this data public. Any experts know?
Seems like some traces are available (Here is the SF East Bay -
[https://earthquake.usgs.gov/monitoring/seismograms/9](https://earthquake.usgs.gov/monitoring/seismograms/9))
but I'm not sure how to interpret this or where the older data is.

Edit: the article mentioned a relevant tweet
[https://twitter.com/celestelabedz/status/1243306005456289792...](https://twitter.com/celestelabedz/status/1243306005456289792/photo/1)

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anigbrowl
I'm not missing the air pollution either.

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pwinnski
Weekdays are now at similar levels to weekends previously. Somewhat amazing.

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ASalazarMX
TL;DR: Cities in lockdown cause less background noise in seismometers.

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elliotec
Thanks, yeah this isn't like fewer earthquakes, it's less non-tectonic
movement so we can hear the earthquakes better.

