Scepticism met North Korea’s claims that last January’s test involved an H-bomb. The latest one leaves less room for doubt
North Korea’s nuclear test created tremors around the world. Shockwaves were first picked up at a seismic station 230 miles away in Mudanjiang, China, where the needle sprang into action less than a minute after the blast. Seconds later, the tremors reached instruments in South Korea and Japan, and within 12 minutes had been detected in Canada, Australia and at the Eskdalemuir Observatory in Scotland.
More than 130 stations recorded shockwaves, which after 20 minutes had reached as far as Argentina 12,000 miles from the test site.
Link : Did North Korea just test a hydrogen bomb? | Ian Sample