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How scientists (including an SMU seismologist) monitor North Korea's nuclear tests

Excerpt

The following is from the Sept. 8, 2017, edition of The Dallas Morning News.

September 11, 2017

By Anna Kuchment
Staff Writer

At 9:30 p.m. Central time last Saturday, detectors around the world picked up signs of a massive explosion in the vicinity of North Korea's nuclear test site.  

The country claimed, for the second time in less than two years, that it had successfully detonated a hydrogen bomb, a weapon far more powerful than the bombs dropped on the Japanese cities of Hiroshima and Nagasaki during World War II.  

The last time North Korea said it had a hydrogen bomb, in January 2016, experts quickly dismissed its claim. This time, some say it's a possibility.  

"The magnitude of this event is bigger than any U.S. or Russian test since the early '70s," said Brian Stump, a seismologist at Southern Methodist University, which operates two seismic detectors for the Comprehensive Test Ban Treaty Organization. 

Shock waves from the explosion clearly registered on the SMU-operated detectors near Big Bend National Park in Texas and in Mina, Nev.  Here's what scientists know about the event — and how they know it.

How was this explosion different from North Korea's previous tests? 

It was much more powerful. North Korea's previous nuclear test, in September 2016, registered as a 5.3-magnitude tremor. Last weekend's explosion set off a 6.3-magnitude earthquake, according to the U.S. Geological Survey. 

"This event, in my mind, is at least an order of magnitude bigger than the event last year," said Stump. "It's a significant increase in yield."

There was also a smaller second event that followed 8.5 minutes after the first one, said Stump. He wonders if it was an aftershock or, perhaps, a sign of a tunnel collapse inside Mount Mantap, the mile-high peak inside which North Korea tests its nuclear weapons.

 

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