Determination of Tectonic Release from Surface Waves Generated by Nuclear Explosions in Eastern

Equalized amplitudes of Rayleigh waves from seven Shagan River events have been compared with the radiation patterns of theoretical models in order to determine their source mechanisms. The results indicate that tectonic release implies both strike-slip and dip-slip motion along faults striking in the northwest-southeast direction consistent with the regional tectonics. Six events fit thrust-slip models with strike azimuths fairly constricted around 144 °. This value agrees well with the strike azimuth of major fault systems in the source region. One event fits a strike-slip model striking at 123 °. Estimated relative source strengths (F factors) are ranging from 0.4 to 4,0 but the estimates are sensitive to minor adjustments of the modeled fault motion