Not really. Gravity waves are just changes in gravity, right?
Beyond the event horizon, our knowledge of the laws of physics breaks down. Gravity, time, etc, all become undefined. We can estimate the mass of a black hole by its gravitational pull, which we assume is due to its mass. And if it were to increase in mass due to infalling matter, I am sure that could be detected also, if the infalling matter were large enough. Gravity waves are time dependent. As gravity changes over time, ripples in space can be interpreted as gravity waves. Since even time breaks down inside the event horizon of a black hole, changes in matter that might cause cause gravity waves would not be be detectable outside the event horizon. The event horizon is a complete break from normal space and the mass of the black hole. Yes, the gravity of a black hole can change, but we would not recognized that change as time dependent waves. I hope this helps. Sources: http://en.wikipedia.
