Waveforms clearly show nuclear test

At 10:35 a.m. yesterday, a line appeared on the electronic situation board at the Earthquake Research Center. The line was connecting to a region in North Hamgyong province in North Korea. All the main researchers at the center, as well as other earthquake scientists and meteorology agency researchers, simultaneously received text messages on their cellular phones, alerting them of the time, place and scale of the earthquake. The size of the earthquake was between 3.3 and 3.9 on the Richter scale, according to the center. The system has an automatic “alarm” system, so that any earthquake in Korea above 2.5 triggers a text message to all related earthquake experts. The Earthquake Center, a research facility within the Korea Institute of Geoscience and Mineral Resources in Daejeon, was operating in an emergency state since news of possible nuclear tests had been publicized. Researchers were prompt to respond to the text messages, and gathered at the center. By looking at the seismic waveforms, they could immediately tell the movement was not from natural causes. Unless there had been a massive gunpowder blast, the only likely cause was a nuclear test. It takes almost 1,000 tons of dynamite to create an artificial earthquake on the scale of 3.9. “From the waveforms, we knew it was an artificial explosion from a nuclear test,” said Lee Hee-il, a researcher at the center. “We immediately began detailed analysis.” Defense Ministry officials who had been dispatched to the Earthquake Center alerted military intelligence. It took just minutes for the information to reach top officials. Examining the waveforms showed whether the tests were nuclear tests. The distance between the Earthquake Center and the test site was about 440 kilometers (273 miles), and it took less than a minute for the waves to reach the center. Unlike natural earthquakes, waves from nuclear tests are “silent” after an explosion. The frequency rate was also similar to that of underground nuclear tests in Pakistan in May of 1998. by Park Bang-ju