On the Atomic Rockets site, there is a series of handy tables, the first of which is aptly named "The Boom Table", providing examples for a wide range of energy releases (in both Joules and TNT equivalent). 3.2×10^26 Joules, or 77 petatons of TNT, is listed as being sufficient to blow away Earth's atmosphere, and presumably cause catastrophic damage to the planet's surface. Assuming the math to determine that this release would be sufficient to nullify a world's atmosphere is accurate, what planetary fortifications would be sufficient to withstand an indirect impact?
Ideally, the atmosphere within said fortifications would remain at survivable pressures. Ideas I've considered:
- Terranean nuclear/WMD bunker. Designed to withstand extreme temperatures and pressures. Direct exposure to the blast wave of super-compressed atmosphere would be extremely risky, regardless of the materials used to construct it.
- Subterranean nuclear/WMD shelter. Designed to withstand extreme temperatures and pressures. No direct contact with the blast would be made, but would nonetheless suffer from the considerable seismological events triggered by such a massive explosion.
- Suboceanic facility. Seismological effects would still be considerable, but the catastrophic tidal effects would be a far more apparent.
Of these three, the subterranean shelter seems most-feasible, but is not without its share of Achilles' heels.
Edit: For clarification, a terrestrial solution would be preferable; simply avoiding the effects of the blast isn't quite the same as sufficiently withstanding it.
Edit 2: By "indirect impact", I mean that the structure is not directly beneath/taking the full brunt of the explosion, but rather situated anywhere between ground zero's perimeter and the opposite side of the world. As for materials from which the shelter would constructed, a near-futuristic (~100 years into the future) technology level may be assumed, and all of the advances in metallurgy and materials sciences that accompany it.
I am also not asking for a structure to be designed, the physics behinds its strength in accompaniment; merely a conceptual presentation as to what sort of structure would be able to withstand the blast wave, given appropriate geography.