2nd test 'four times' stronger

TOKYO: The DPRK's nuclear test yesterday was believed to be four times more powerful than its first atomic test in 2006, the Japan Meteorological Agency said.

"The seismic activity detected today was of magnitude 5.3, while that of the previous nuclear test was magnitude 4.9," said Yasuo Sekita, an official of the Japanese agency which monitors both weather and seismic activity.

"The impact of a tremor doubles for every 0.2 in magnitude," he said. "This means the energy level of today's nuclear test was four times bigger than the last one."