Magnitude: Yield for Nuclear Explosions in Granite at the Nevada Test Site and Algeria: Joint Determination with Station Effects and with Data Containing Clipped and Low-Amplitude Signals

A systematic approach to short-period magnitude estimation has been developed and applied. The approach uses newly developed statistical techniques in the general linear model (GLM) which allow for the problems of clipping and of signals hidden by noise. Measurement procedures are outlined and the overall approach is first applied to four events in granite; PILEDRIVER, SHOAL, SAPHIRE, and RUBIS. The WWSSN short-period network film recordings, with the application of this approach, form an ideal network for shots over 10 kt in hard rock. After correction for the effects of pP, estimated via synthetic waveform calculations, the magnitudes follow a theoretical magnitude: yield curve which changes from a slope of 1.0 near 10 kt to a slope of 0.8 near 100 kt. The offset between the US and Sahara explosions is 0.04 to 0.12 mb units, with US events biased low. It is not clear from the data if this is due to t*, or to coupling differences. Station corrections determined from a suite of 9 explosions at different test sites around the world show good correlation with residuals estimated by North.