The Detection of Underground Explosions

Leet, L. Don

doi:10.1038/scientificamerican0662-55

Cited by 8 publications

(5 citation statements)

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“…Leet (1962) commented on the low S and surface wave energies relative to P at teleseismic distances as a possible discriminant in detection of underground nuclear explosions. Brune, Espinosa & Oliver (1963) compared the recorded surface wave envelope areas of explosions and earthquakes to local Richter magnitude, ML, finding generally 5-10 times greater surface waves from earthquakes than explosions of the same magnitude, with regional variations of a factor of 5.…”

Section: Rayleigh and P Amplitudesmentioning

confidence: 99%

Source Characteristics of Earthquakes, Explosions and Afterevents

McEvilly

Peppin

1972

Geophysical Journal International

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Broad-band seismic data available on the magnetic tape library at Berkeley have been used in a study comparing P, and Rayleigh waves from earthquakes, explosions and explosion afterevents, both collapse and earthquake types. Eighty-one events equidistant from Berkeley at 500-550 km provided the data for wave amplitude and spectra comparisons. Explosions exhibit characteristic low Rayleigh wave (12-s period) generation, for given P,, amplitude, relative to earthquakes as well as explosion afterevents. This discriminant, for events recorded at Berkeley, is well developed down to local magnitude M,, 4.0 or less (m; R 3.6) and shows no indication of convergence, although scatter increases, for smaller events. Rayleigh wave spectra for explosions and collapses are quite similar, the similarity continuing up to frequencies of 0.5 Hz for proximate events. However, they differ significantly from spectra of shallow earthquakes in the same source region. This implies the explosions, including those large ones with appreciable surface faulting, Love wave generation, and aftershock sequences, are sources with small time and space dimensions, relative to shallow earthquakes at the same site. Extensive fault displacements near large explosions is proposed as passive medium response to strong shaking and Love wave generation with Rayleigh wave asymmetry is suggested to occur through processes acting in the relatively small high stress explosive source region.

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Section: Rayleigh and P Amplitudesmentioning

confidence: 99%

Source Characteristics of Earthquakes, Explosions and Afterevents

McEvilly

Peppin

1972

Geophysical Journal International

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“…Each of several criteria proposed in the past few years will be discussed in turn, and their usefulness in a network designed for worldwide surveillance will be clarified. Leer [1962] and Bullard [1966]…”

Section: Introductionmentioning

confidence: 99%

Identification of earthquakes and explosions by use of teleseismic data

Evernden¹

1969

J. Geophys. Res.

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Criteria for achieving an order of magnitude discrimination between underground explosions and shallow‐focus continental earthquakes are presented. The basis of all these criteria is the gross difference between earthquakes and explosions as regards their relative generation of short‐ and long‐period waves. It is also shown that depth of focus of small events can be accurately determined either by use of master‐controlled travel‐time corrections or by determination of time of origin (Pg, S‐P, etc.). Therefore, the basic problem for differentiating earthquakes and underground explosions of magnitude 4¾ or greater by seismic criteria has been solved. The remaining problems are the detection of long‐period waves at low signal‐to‐noise ratios and the evaluation of the applicability of long‐period identification criteria for low‐magnitude events.

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“…Some of this work had in fact been known for many years, but in the context of studying the signals from quarry blasts, which are typically too small to detect except at regional distances. Thus, a Harvard seismologist, Don Leet, who had specialized in the study of quarry blasting, noted from teleseismic records of underground nuclear explosions that they often lacked any S-wave signals even when the P-wave was strong [35]. For earthquakes, the S-wave is usually much stronger than P. The use of what Leet called the "lonesome P" discriminant, however, was unreliable, for many nuclear explosion records did in fact include S-wave signals.…”

Section: Further Comment On Key Technical Issues In Seismic Monitoringmentioning

confidence: 99%

“…Penney believed [7, pp. [26][27][28][29][30][31][32][33][34][35] that such a system would detect and identify 90% of the earthquakes equivalent to 5 kilotons or more, and a small percentage of those equivalent to one kiloton. The other 10% of 5 kt equivalent events would have to be inspected, and estimates of the number of such events ranged from 20 per year (USSR estimate) to 100 per year (US estimate).…”

Section: History Of the Treatment Of Ctbt Verification 1957-1963mentioning

confidence: 99%