The Gents; Virtual meeting 2016, LIGO questions
Why seismic waves are important to LIGO
All kinds of things shake the ground and therefore affect the interferometers. These background vibrations have to be "subracted" just as background radiation is subtracted to determine radiation from a radioactive source.
sources of seismic waves
Almost anything that moves on the ground, hits the ground, or otherwise sends vibrations through the earth: earthquakes, trucks driving, mining explosions, weather phenomena, volcanoes, a gnat sneezing too close to the interferometer, etc. etc.
How are seismic waves measured
Seismometers have three instruments that measure movement in each of the 3 dimensions, By combining the three measurements scientists can determine exactly the direction, amplitude, and duration of seismic movement.