ZURICH - Nuclear proliferation watchdog CTBTO said on Saturday it had detected two seismic events in North Korea on Saturday but they were probably not deliberate explosions in the isolated country."Two #Seismic Events! 0829UTC & much smaller @ 0443UTC unlikely Man-made! Similar to "collapse" event 8.5 mins after DPRK6! Analysis ongoing," CTBTO Executive Secretary Lassina Zerbo said in a Twitter post.China's earthquake administration said it had detected a magnitude 3.4 earthquake in North Korea that was a "suspected explosion," while an official at South Korea's meteorological agency said the initial view was that it was a natural quake.