This is site at Mount Montop later this month. Shortly thereafter President Trump is set to meet

North Korea's leader, Kim Jong-un, in Singapore. Regardless of how that goes, there is now an

additional tool to investigate covert subterranean tests, radar,

specifically a type called synthetic aperture radar,

which works day and night and through clouds.

Scientists already use seismic data in their nuclear

detective work. You know we use the kind of techniques that earthquake seismologists

used to figure out some aspects of what that explosion did.

Roland Bergman, a geophysicist at the University of California, Berkeley.

He says they can also measure isotopes in the air,

as well as optical images pre and post explosion.

Now Bergman and his team have used synthetic aperture radar data from German and Japanese

satellites to gather more clues about North Korea's biggest blast in September 2017.

Comparing before and after scans of the test site,

their analysis found that the mountain bulged a dozen feet

in one direction and sunk a foot and a half.

Using computational modeling, they then simulated

what sort of blasts could have produced those movements.

In their estimate, the blast was at least six times

as strong as the bomb the US dropped on Nagasaki in World War II.

The details are in the journal Science.

Our study shows that this is an especially valuable observation that can be thrown into the mix.

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