Haven't looked it up, but isn't that also an H-bomb? I assume it is if it is the most powerful detonation ever. So in an H-bomb, most of the energy comes from the fusion of hydrogen atoms into helium. There is a regular fission bomb, but probably quite a small one since it's really just the trigger for the hydrogen bomb to get fusion to begin. There is some radiation associated with this, but not to the extent of there being huge numbers of long-lived isotopes hanging around to make the place still uninhabitable. Eh, I'm wrong again. There will still be plenty of isotopes around during and right after the blast, since a lot of energy results from further fission on not-normally fissile materials, like depleted uranium. But isotopes all decay over time, and get dispersed by wind, water, etc. After a long time, everything is either decayed or dispersed and is in very low concentrations. There are very few places still uninhabitable really. Even Hiroshima is fully inhabited, a thriving city now. Nature is even reclaiming Chernobyl now, slowly but surely things are growing and living there.
The US also detonated some H-bombs in the Pacific, on Bikini Atoll and such. There is at least one island that ceased to exist when an H-bomb was detonated on/over it, it completely destroyed the entire island. The US and Russia both did some pretty terrible things after WWII with not knowing enough about radiation and not telling people the real effects. Those islands in the Pacific that the US used were inhabited islands, so the people basically got kicked off their home islands. Back in the US, the Army did testing and drills in Nevada with US soldiers involved, not telling them the real effects.
I've seen a video of a drill they did with a "tactical" nuclear weapon that could actually be fired from a smallish cannon. They did this whole drill of there's an enemy army approaching, so the US soldiers hunkered down in trenches, they fired the cannon-based weapon, and the video shows soldiers seeing the explosion, ducking into the trenches until the shockwave went by, then jumping up out of the trenches and running towards the blast zone to fight the fake army/finish them off as part of the drill. Literally sending hundreds of US troops straight into the blast zone while the mushroom cloud was still in the air. Imagine the levels of radiation those troops got in an exercise for something that we know now would be a terrible idea (since it is pretty much recognized now that nuclear weapons are not a tactic, they are instead a strategy and are too extreme/damaging to ever be considered simply a tactic).
It was detonated over the Novaya Zemlya archipelago and the shockwave is said to have broken windows in Finland.That's quite a feat. :-/
If they were able to make a bomb capable of a 100 kiloton blast in 1961, who knows what way more powerful and efficient stuff they can make now. 
