No, both gravitational waves and electromagnetic waves decrease in intensity with the square of distance.

(This is true of any wave in 3D space, because the area covered by a wavefront increases with the square of distance. The inverse square law is a consequence of conservation of energy.)

The energy of the gravitational waves will decrease with the square of the distance, but the amplitude will not. We can detect this in LIGO. This amplitude is also known as "strain". For more discussion check this page: http://spiff.rit.edu/classes/ast613/lectures/grav_i/grav_i.h...

The equation for strain is: http://spiff.rit.edu/classes/ast613/lectures/grav_i/eqn_stra...

The same is true of electromagnetic waves. The amplitude of EM waves decreases inversely with distance, and the energy decreases with the inverse square.

Your original comparison of EM waves to gravitational waves is only possible because you looked at the power of one, and the amplitude of the other. If you compare apples to apples, they're the same.

A question for typon: in light of this information, do you still believe that advanced enough civilizations would use gravitational waves for communication?