It is one of the mysteries of Japan's ongoing nuclear crisis: How much damage did the March 11 earthquake do to the Fukushima Daiichi reactors before the tsunami hit? The stakes are high: If the quake structurally compromised the plant and the safety of its nuclear fuel, then every other similar reactor in Japan will have to be reviewed and possibly shut down. With virtually all of Japan's 54 reactors either offline (35) or scheduled for shutdown by next April, the issue of structural safety looms over the decision to restart every one in the months and years after.