May have shortened the day by 3 microseconds, said gravity expert Richard Gross of Jet Propulsion Laboratory, Pasadena... On premise a slab slid into core, Gross said he's done calculations 'to see what effect this (earthquake) should have had.' The result: A day shortened... 'We won't know for weeks,' said a geophysicist at Massachusetts Institute of Technology. 'So it's a guess, as of now'...