Relative locations among the 2006, 2009 and 2013 North Korean underground nuclear tests

The relative locations among the 9 October 2006, 25 May 2009, and 12 February 2013 North Korean underground nuclear tests are estimated by the double-difference location algorithm, using the relative times of P signals as well as those of S and LR signals.And location uncertainties are analyzed by bootstrap method.The relative times are measured with cross-correlation technique, using vertical waveform data recorded at 19 regional and 8 teleseismic stations.The results show that the 2013 test locates 257 m south and 385 m west relative to the 2009 test with about 150 m uncertainty estimated with 20 stations resampling at 95% confidence level, and the 2006 test is about 503 m south and 2589 m east to the 2009 test with the same uncertainty.