Yield estimation from surface-wave amplitudes

Citation
Jl. Stevens et Jr. Murphy, Yield estimation from surface-wave amplitudes, PUR A GEOPH, 158(11), 2001, pp. 2227-2251
Citations number
33
Categorie Soggetti
Earth Sciences
Journal title
PURE AND APPLIED GEOPHYSICS
ISSN journal
00334553 → ACNP
Volume
158
Issue
11
Year of publication
2001
Pages
2227 - 2251
Database
ISI
SICI code
0033-4553(200111)158:11<2227:YEFSA>2.0.ZU;2-F
Abstract
Surface-wave amplitudes from explosion sources show less variation for a gi ven event than body wave amplitudes, so it is natural to expect that yield estimates derived from surface waves will be more accurate than yield estim ates derived from body waves. However, yield estimation from surface waves is complicated by the presence of tectonic strain release, which acts like one or more earthquake sources superimposed on top of the explosion, Moment -tensor inversion can be used to remove the tectonic component of the surfa ce waves, however moment-tensor inversion for shallow sources is inherently non-unique so the explosion isotropic moment cannot be determined with the necessary accuracy by this means. Explosions on an island or near a mounta in slope can exhibit anomalous surface waves similar to those caused by tec tonic strain release. These complications cause yield estimates derived fro m surface waves to be less accurate than yield estimates from body waves re corded on a well-calibrated network with good coverage. Surface-wave amplit udes can be expressed as a surface-wave magnitude M-s, which is defined as the logarithm of the amplitude plus a distance correction, or as a path cor rected spectral magnitude, log M-0', which is derived from the surface-wave spectrum. We derive relations for M-s vs. yield and log M-0' vs, yield for a large data set and estimate the accuracy of these estimates.