Do Blasts Pass Through Obsidian?

I'm in a bit of a pickle.

It seems someone playing on my friend's SMP server decided that it would be a good idea for him to do some testing with TNT.

Now, he's conscientiously set this atrocity up a reasonable distance from the rest of the construction on the server, so I don't think that it will effect any damage in the other projects, but someone still has to get rid of it. Guess Who.

This is what I've come up with, as a means of surviving the cataclysm:

However, this shelter is of course, based on the assumption that since Obsidian cannot be destroyed by explosions, it will act as a barrier to their consequences. If I were to hide inside this shelter, would I emerge unscathed after detonating the TNT?

Anecdotally, from the explosion patterns on another question, I never saw a block that was further from the center being destroyed while another, closer block wasn't. All my target blocks (redstone) had 0 resistance, so anything touching them should have popped them (though they do have a sort of resistance when they get destroyed).

The mechanics as described on the Explosion page over on the Minecraft Wiki state that they are modeled as rays originating from the explosion center travelling out until they are fully attenuated. If they all meet an impenetrable wall (obsidian), they can all be absorbed and nothing gets through.

I LIVED.

Based on this, it appears that yes, obsidian 'blocks' the effects of explosions. My health meter flashed, and my character said Oof! a bunch of times, but no damage was taken.

Depending on how you define "passing through", because explosion has different effects on blocks and entities.

According to the Minecraft wiki article on explosion, entities (including you the player) will always get at least 1 point (half-heart) damage if they are within blast radius (TNT: 8, creepers: 6, fireballs: 2), regardless of explosion exposure (calculated with sophisticate algorithm, or simply how much you're covered by obsidian). And the damage can be absorbed by armor subsequently.

The above statement is reproducible for me with a 1.5_01 client. However, the main part of that article was written by me based on disassembled code, so I can't provide more verifiable sources than this.

I don't know if this would work on large areas like yours, but according to the minecraft wiki, water will block terrain damage (but not player/mob damage).

I did a similar experiment with obsidian. I placed tnt all around an obsidian box. Then I put four chests in the obsidian box. After covering all the walls with obsidian and then setting off the tnt, 3 of the four chests that were in the obsidian were destroyed. My conclusion: even though explosions don't destroy obsidian, they still go through the obsidian block and can damage blocks inside the box.