When living in San Francisco, the thought of commuting everyday on the BART train that goes under the San Francisco Bay was always a frightening thought until I saw something on TV that mentioned that that particular tunnel was much safer than you would think.

I'm sure every underwater tunnel is different, but in this case, the expert mentioned that ground movement is generally less intense as you go down into the earth, compared to a thin, swaying skyscraper, so the tunnel would be subject to less shaking than above ground structures. Plus, being a tunnel, they are naturally quite robust in their construction.

Anyway, still a frightening thought, but it did make me feel better about it. (crossing fingers)