"Distortions in the very fabric of space and time" as Einstein believed. It could possibly ripple outward throughout the universe at the speed of light. Unfortunately no one has found any indirect evidence of this occurring. However this may not the case for long as astronomers have acquired newer and improved equipment that continues to better from recent advances in technology.
A proposed Laser Interferometer Space Antenna could be the tech we need to detect these events. This equipment would be designed for use in space. It continues to be a high priority among the astronomical communities and several groups are looking forward to its completion. Current methods employ the user of computational models to explore the mergers of super sized black holes.