RFID and earthquakes
One major thing everyone overlooks is the range of RFID. To be small enough to comfortably fit in a human only a passive unit with a small antenna can be used. This limits the range since the power has to be pushed to the RFID tag. You're going to get a range of maybe a meter.
Additionally no materials that respond to a magnetic field can be used, as it would tear out the tag during an MRI. From a security standpoint, want to become someone else? take their chip. After all, it's a perfect ID system, so if it says you're joe, there's no way you could be bob with joe's chip. (This is why there are photos on id, although it's much more difficult to steal a chip than a card)
I've also never figured out how they can listen to multiple tags at once, the same type of tag is going to be on the same frequency, so don't their transmissions overlap?
Finally there is no time when an earthquake is supposed to happen, except for aftershocks (in which case if the original earthquake is strong enough to warrant getting your tag, it's probably too late anyways)