[topher]

This is map of H-bomb test - 6.3 quake at depth 0.0 km:

My conclusion is MOUNTAIN has collapsed from previous nuclear tests...

[topher]

Fat Boy does not have resources to dig a tunnel down 5 kilometers. It is about the right size for mountain to collapse.

Discussion of MOUNTAIN collapsing was that horizontal tunnel was dug for all 6 nuclear tests. Too hard to dig down for tests. But this also was reason MOUNTAIN might collapse.

Should be radio-active fallout detected first in Russia, then China, and finally South Korea. Japan is farthest away, so they might detect radiation next.