The size or effective distortion field of a gravitational-wave perturbation at any given location in space-time is determined by the distance separating the source and that location. This describes a gradient of gravitational-wave intensity that ranges from the minuscule to the macroscopic. So, a confluence of gravitational sources sufficiently large within the Milky Way galaxy for example or within 1000 ly of the earth will yield a much larger gravity wave, a wave that may even cause damage. So why does no one speak of this?
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Because even the strongest sources are fairly weak. The peak strain of GW150914 was only $10^{-21}$. Of course, it would be stronger if it had originate closer to the earth. However, since the strain is inversely proportional to distance, even putting it as close as our nearest star would only increase the strain by a factor of $10^9$ (a bit less actually). Hence, even a bh merger happend at our nearest neigbour in space, the observed strain on Earth would less than $10^{-12}$. This corresponds to a deformation of the Earth of maybe 10s of nanometers.
Hence, we simply do not know of any possible sources that would produce gravitational waves that would be "large" when they would reach Earth. Moreover, if such sources would exist (in the LIGO frequency band), they would have been observed. Hence, not observing any such sources confirms that they don't exist (or are at least extremely rare).
TimRias
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gravitational sources sufficiently large within the Milky Way galaxy for example
The problem comes down to "what example"? Generation gravitational waves requires massive and rapid changes in mass distribution. There are only a few events that can cause this, like black hole mergers. Colliding (normal) stars and even supernovas just don't have the oomph. I suspect the rebound in the later case might be detectable at close range, but likely only well within the ~1000 ly lethal range so it would be difficult to know for sure.
Maury Markowitz
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