Abstract
For nearly the past 2 decades, regional shear wave coda has been shown to provide the most stable estimates of the explosion and earthquake source, making its use ideal when station coverage is sparse. As a result, momentmagnitude is determined with unprecedented stability from as few as one station and is being used in a number of explosion monitoring applications. In spite of its success, a significant magnitude bias exists for S-based regional magnitudes such as mb(Lg) and mb (Lg-coda) between explosions and earthquakes when compared to their teleseismic mb(P) counterpart. In this study, we first show preliminary results for regional and nearteleseismc P-coda for both earthquakes and explosions to see if a bias still exists with the teleseismic mb. In addition, there is a point of debate on whether the regional P-coda calibration will remove the effects of the path and upper mantle effects which bias teleseismic mb(P) estimates for some test sites. We find that the P-coda does not exhibit a magnitude bias between earthquakes and explosions, in sharp contrast to S-based magnitudes such as mb(Lg) when compared to the teleseismic mb(P). We plan to give a summary of regional coda research and specifically address our recent P-coda findings.