Absolute explosive yield from spectral ratios of regional distance P-wave coda

In this study we develop a framework which uses the source information obtained from the spectral ratios of envelopes of measured seismic coda waves to invert for model-derived (e.g., Muller-Murphy, 1971) explosive yields and depths-of-burial (DOB). Using synthetic tests, we quantify the error present in the inverted source parameters and explore the parameter trade-off between yield and depth. In order to limit the ambiguity associated with the parameter trade-offs, and reduce the null space of the inversion, we examine the effect of including a co-located earthquake with a known hypocenter and magnitude in the inversion scheme. We find for both cases which include and do not include a known earthquake, that the coda spectral ratio derived inversion scheme provides accurate DOB and absolute yield estimates. We further show, and quantify, how the inclusion of the earthquake reduces the uncertainty in the absolute yield, and constrains the trade-off between DOB and yield. We then validate this novel inversion framework by applying it to regional distance measurements of P-wave coda of seismic events in North Korea, including the six announced nuclear tests and nearby earthquakes. We report inverted yields and DOBs which compare well against those estimated in previous studies. Additionally, we show how prior information about source depth can be included, using a Markov Chain Monte Carlo (MCMC) procedure, to further reduce the trade-off between DOB and yield.