Body-Wave Magnitudes and Locations of Presumed Explosions at the Chinese Test Site, 1967-1996

摘要

For nearly 40 years the forensic seismology group at Blacknest have published estimates of the basic parameters of presumed explosions (epicentre, origin time, body-wave magnitude) determined using state- of-the-art methods from bulletin data (usually the International Seismological Centre (ISC) bulletin). These basic parameters are widely considered to be some of the most reliable estimates that are freely available. However, not all presumed explosions have been analysed. Here, we estimate the epicentres and body-wave magnitudes of presumed underground explosions at the Chinese test site in Xinjiang Province using ISC bulletin data, supplemented by P-onset times measured from data recorded by the four UK-type seismometer arrays (EKA, GBA, WRA, YKA). The epicentres are estimated using Joint Epicentre Determination. The body-wave magnitudes are calculated using the Joint Maximum-Likelihood method. This work builds on an earlier report that reviewed epicentres and body- wave magnitudes for 17 presumed Chinese explosions red between 1967 and 1989. A further 11 presumed explosions, dated from 1990 to 1996, are analysed to complete the set. The estimates of the epicentres of the presumed explosions suggest that a number of different regions exist within the test site. The seismograms at each of the UK-type arrays for these presumed explosions appear to display common features which may relate to specific regions of the test site. Here, we attempt to distinguish the different areas of the test site using the P-wave characteristics observed at the 4 UK-type arrays.