Wouldn't work. Alice and Bob have no way of knowing whether the detected correlation is from Victor observing an earthquake, or Victor being instructed to entangle. Alice, Bob, nor Victor have any way of telling how many times this "message" has repeated backwards in time. Your process creates an infinite loop backwards in time "starting" from an earthquake. The lab staff noticing that Alice and Bob have correlated polarization only tells them that a disaster will occur, not "shortly" because the process has no timeout.
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Probably safest not to bite any midges OR hobbits.