Relative Relocations of the North Korean Nuclear Tests From 2006 to 2017 Using the Hi-Net Array in Japan

Abstract

Precisely locating sites of nuclear tests is important for the Comprehensive Nuclear-Test-Ban Treaty and structure studies. Here we apply a relative relocation method to a dense regional seismic array, Hi-net, to determine the relative locations of the sites of the North Korean nuclear tests from 2006 to 2017. Our results show that the sites of the 2013 to 2017 events are closely located together and within 600 m of the site of the 2009 event. The site of the 2006 event is located ~2 km southeast to the site of the 2009 event. A bootstrap resampling of azimuthal subsets of the array adds confidence to the relative locations. Seismic data recorded at regional distance by a dense network with azimuthal coverage as limited as 80° can resolve the relative locations of the nuclear tests to within a few hundred meters for all but the 2006 event. This approach can be extended to locating natural earthquakes as well.