What is Seismic Noise? – UPSC GS1

 Why in news?
The seismic noise level has dropped by as much as 50 per cent between March and May due to lockdowns this year, according to researchers.

What is Seismic Noise?

  • Seismic noise refers to vibrations within the Earth, which are triggered by natural and man-made phenomena like earthquakes, volcanoes and bombs.
  • Seismometers, specialised devices that record ground motions, also capture seismic noise.
  • Everyday human activity — such as road traffic, manufacturing in factories, the sound produced by planes roaring overhead, or simply people walking down the street.
  • The sound signals created by human beings are often referred to as anthropogenic seismic noise.
  • Seismic noise acts almost like background sound for seismologists — it is the unwanted component of signals recorded by a seismometer.

Variations in noise levels

  • The level of anthropogenic seismic noise recorded varies based on a number of factors.
  • Highly-populated urban areas will generate more vibrations from human activity than less densely populated regions.
  • Timing too plays an important role. The degree of seismic noise is found to be much lower during public holidays.

Why is this important to record this noise?

  • Due to this, scientists will be able to spot weaker signals.
  • Such small signals tell us about a geological fault making seismic hazard assessment more accurate.
  • This means that scientists will have a better shot at monitoring a whole range of seismogenic behavior, including the smallest earthquakes or the early signs of a volcanic eruption.
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