The Surface Wave Magnitude for the 9 October 2006 North Korean Nuclear Explosion

Abstract

Surface waves were generated by the North Korean nuclear explosion of 9 October 2006 and recorded at epicentral distances up to 34 degrees, from which we estimated a surface wave magnitude (M{sub s}) of 2.94 with an interstation standard deviation of 0.17 magnitude units. The International Data Centre estimated a body wave magnitude (m{sub b}) of 4.1. This is the only explosion we have analyzed that was not easily screened as an explosion based on the differences between the M{sub s} and m{sub b} estimates. Additionally, this M{sub s} predicts a yield, based on empirical M{sub s}/Yield relationships, that is almost an order of magnitude larger then the 0.5 to 1 kiloton reported for this explosion. We investigate how emplacement medium effects on surface wave moment and magnitude may have contributed to the yield discrepancy.