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That is not totally correct, if I may. Gravitational wave carry a lot of energy, but this energy is not dissipated (in a first approximation). It stays within the wave. The fraction of energy used to deform space (which is what is measured) is really tiny and negligible.

So although the wave is very energetic, their energy is not what is detected :)

It is however true the wave is getting fainter due to the traveled distance from the source (propagation in a plane) and the expansion of the universe.

Correct. I should have said "to detect the most energetic event."

Then I agree ^^