Quake-Proof Oceanic Tunnels

It has been proposed in several places that tunnels be built across the oceans. It seems to me that these dreams will be unrealized due to the vagaries of Nature; such tunnels will cross various high-earthquake rift zones, and eventually be snapped. Even a known variation on the tunnelling theme, that of letting the tunnel-tube float in the water, but tethering it to the bottom and keeping it IN the water, more than a hundred feet down, is not perfect. When the ocean floor heaves, conventional anchor blocks move, too! And so will the tethering cables, and thus also the attached tunnel. Not good! But here is how to quake-proof them:

The anchor blocks on the ocean floor should be placed on smoothed-out surfaces (not necessarily as slippery as Teflon), so if the ground under a block shifts, its mass holds it in place, not unlike the tuned-mass motion-dampers on top of various tall skyscrapers. Repair would merely consist of preparing some more seafloor in the direction the block shifted, to accommodate future horizontal shifts. Vertical shifts are a bit more problematic. Perhaps each tether cable should include a reel with extra cable, and automatic tensioning devices that take up slack when it appears (seafloor heaves up), and unreels fresh cable when needed (seafloor sinks). I'm not sure if any such tensioning devices exist for cable reels (they do exist for 10-speed bicycle chains :), but I see no reason why they couldn't.

So, now we have this nice pair of tubes stretching across the ocean, deep enough so no ship will run into them (submarines and SINKING ships excepted, although the tethering system does have some built-in "give" to it, which may ultimately be deliberately enhanced to prevent damage from exactly such incidents).

On to the vehicles! The tubes could be made of glass (thick-enough glass can be shatterproof even against collision), and the view from inside might be quite interesting. I say "might" because any vehicles in the tube will be running at extreme speed. The tubes might be evacuated for maglev cars (discussed elsewhere), or the cars themselves might be designed to USE the air in the tubes. Consider a tube that has a funnel of just-about the same size placed in it. The funnel would be the front end of a cylindrical tube-car (and another at the rear); turbines along the central axis of the car would suck air in front of the car and expell it out the expanding rear funnel (rocket nozzle), propelling the car forward AND greatly reducing air resistance! A computer-controlled circular airfoil at the edge of the funnel would force some air around the exterior of the cylindrical car, letting it "float" away from the walls of the tunnel, when moving at high speed. Also, each car could have a probocis that could be telescoped to fit in the tail of the car in front (and a tail-end ring-shaped accommodation for a nesting funnel-airfoil), making a twice-as-long car that doesn't waste energy letting air expand and be recompressed between the cars. The lengths of various trains of such cars would be quite variable. They would all have to be electric-powered, of course (via induction, probably).