The Gravitational waves detected by LIGO on 14th September 2015 are attributed to a collision of two black holes, which had been rotating near the speed of light around each other just before the actual collision. The collision happened 1.3 billion years ago, approximately 1.3 billion light-years away and apparently, the energy of the collision exceeded the combined energy of all stars in the observable universe.
LIGO was able to detect the deformation in the fabric of space induced by the gravitational wave caused by the collision (or by the high-speed rotation of the black-holes just before the collision), even though the deformation was the magnitude of a fraction of an atomic radius. The reason why the deformation was so "small" by the time the wave had reached planet Earth was due to the relatively large distance of the collision from Earth.
Question: could someone qualified give an estimate of the magnitude of the space-time deformation we would experience on planet Earth, had the collision happened closer to us? I.e. how close would the collision have to happen for the space-time deformation to be millimeters? What about meters? At what magnitude of the deformation would the gravitational wave be dangerous or lethal for humans on planet Earth?
Bryan Greene described the gravitational wave deformation of space-time as a temporary "shrinkage" or "compression" of Earth (and everything on it). Am I right to assume that being compressed by even 1 centimeter could potentially be lethal for all live on Earth?