Japan Meteorological Agency's earthquake and tsunami observations division director Yasuo Sekita points at a graph of ground motion waveform data observed in the morning in Japan during a news conference in Tokyo on implications that an earthquake sourced around North Korea was triggered by an unnatural reason May 25, 2009. North Korea conducted an underground nuclear test on Monday, stoking tension across the regional economic powerhouse of East Asia and prompting U.N. Security Council members to call an emergency meeting. REUTERS/Yuriko Nakao(JAPAN SCI TECH POLITICS ENVIRONMENT)