Forensic Seismology and the Comprehensive Nuclear-Test-Ban Treaty

Abstract

One application of forensic seismology is to help verify compliance with the Comprehensive Nuclear-Test-Ban Treaty. One of the challenges facing the forensic seismologist is to discriminate between the many thousands of earthquakes of potential interest each year and potential Treaty violations (underground explosions). There are four main methods: (a) ratio of bodyto surface-wave magnitudes, (b) ratio of high-frequency P to S energy, (c) model-based methods, and (d) source depth. Methods (a) and (b) have an empirical basis. The weakness of methods (a)-(c) is the lack of an equivalent elastic source for an underground explosion fired in the range of geological media found around the world. Reliable routine source-depth determination has proved difficult. However, experience gained in the past decade at identifying suspicious seismic sources suggests that although no single method works all of the time, intelligent and original application of complementary methods is usually sufficient to satisfactorily identify the source in question.

Magnitude‐based discrimination of man‐made seismic events from naturally occurring earthquakes in Utah, USA

“…Furthermore, an M L ‐M C discriminant does not rely on the existence of the fast attenuating Rg phase at regional distances. M L ‐M C may provide a local‐to‐regional distance analog of the m b ‐M S discriminant that has traditionally been effective at identifying large nuclear explosions with teleseismic data but has been less successful with recent, smaller‐magnitude nuclear tests in North Korea [ Bowers and Selby , ; Murphy et al , ]; however, for the Utah data set presented here, the M L /M C separation is not distinct enough for an M L ‐M C discriminant to be used in isolation. Rather, an M L ‐M C discriminant would be most effective as one component of a multidiscriminant scheme [ Anderson et al , ].…”

“…This phenomenon is consistent with earlier observations that the existence or amplitude of a short period Rayleigh wave ( Rg ) can be used as an indicator of shallow focal depth because its amplitude is much more sensitive to focal depth than the amplitudes of regional distance body waves such as Pg and Sg [ Båth , ; Kafka , ; Ma and Motazedian , ]. However, short‐period Rg is strongly attenuated with distance and can be difficult to observe beyond 150 km [ Bowers and Selby , ], limiting its usefulness as a depth discriminant. M L ‐M C may be better suited as a depth discriminant, particularly since Rg energy lost to elastic scattering [e.g., Myers et al , ] will contribute to the amplitude and duration of the coda, and thus to M C .…”

Rozlišení vzdálených záznamů přirozených zemětřesení a explozí na příkladu severokorejských jaderných testů

“…Vzhledem k obrovskému množství lokalizovaných jevů je nutné, aby základní odlišení záznamů přirozených zemětřesení od záznamů explozí bylo založeno na takových postupech, které lze automatizovat. Metod využitelných k rozlišení záznamů přirozených zemětřesení a explozí je více (Bowers -Selby 2009;Pomeroy et al 1982; U. S. Congress 1988), přednostně jsou využívány ty, které jsou jednodušší a které lze aplikovat na co největší množství registrovaných seismických jevů.…”

Duties of Earthquake Forecast

“…It seems that the spirit of forensic seismology (Bowers and Selby, 2009), the discipline that was mainly related to the monitoring of a comprehensive nuclear test ban treaty, may also apply to the field of earthquake forecast/prediction. Such decision-making issues include two levels of problems: (1) how to analyze comprehensively the information from different disciplinesdall have some clues leading to the assessment of time-dependent seismic hazard, but all have large uncertaintiesdto get the predictive conclusions so as to communicate with the government; and (2) how to suggest to the government what decisions to take responding to the assessment conclusions for the reduction of earthquake disasters.…”