Source-Depth Determinations using Spectral, Pseudo-Autocorrelation and Cepstral Analysis

Cohen, Theodore J.

doi:10.1111/j.1365-246x.1970.tb06065.x

Cited by 56 publications

(15 citation statements)

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“…There is, however, strong evidence from the literature that this assumption is not appropriate. Cohen [1970], King et al [1972], Bakun and Johnson [1973], and Burdick and Helmberger [1979] have pointed this out for the Amchitka tests, but it also seems to be true in general. Changes in pP relative amplitude and timing have an effect on short-period waveforms similar to the effect of changes in t*.…”

Section: Short-period Amplitudes and The Scatter In Themmentioning

confidence: 95%

Modeling near‐field and teleseismic observations from the Amchitka Test Site

Burdick¹,

Wallace²,

Lay³

1984

J. Geophys. Res.

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During the Amchitka testing program, recordings were made of the near‐field ground velocity for events MILROW and CANNIKIN. These records exhibited a P arrival, a feature associated with near‐field pP and a developing Rayleigh wave. In this investigation, simple models were found which match the complete seismograms. They simultaneously predict the amplitude, wave shape, timing, and periodicity of both the body waves and the surface waves. Models for both the Amchitka crustal structure and the source time functions were developed. The crustal model is similar to previous models in its average properties, so travel time constraints are still satisfied. Small modifications have been made to match the waveform data. The events on Amchitka can apparently be represented as isotropic point sources with the types of simple source time histories predicted by classical yield scaling laws. A source model for event LONGSHOT was developed on the basis of the yield scaling laws since no near‐field records are available for it. The source models were tested by comparing the teleseismic body waveforms they predict with observations. Short‐period P waves, long‐period P waves, and long‐period pS waves were considered. The short‐period P waves provided the best constraint. To match them, it was necessary both to develop a model for teleseismic pP since it arrives later than the near‐field model would predict and to estimate the average value of t*. The MILROW and CANNIKIN teleseismic short‐period P waves indicate that the average effective tα* for teleseismic ray paths from Amchitka is 0.9 s. The scatter about this value, however, is very substantial. The accuracy of the scaling laws was tested by comparing synthetics for LONGSHOT to teleseismic observations. The predicted amplitudes and wave shapes fall within the scatter in the observations, though again this scatter is substantial.

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Section: Short-period Amplitudes and The Scatter In Themmentioning

confidence: 95%

Modeling near‐field and teleseismic observations from the Amchitka Test Site

Burdick¹,

Wallace²,

Lay³

1984

J. Geophys. Res.

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“…Carrying this argument further, note that many investigators have estimated detonation depths of explosions from short-period P waves or their spectra (Cohen, 1970;Kulhanek, 1971;Douglas et al, 1972a;Frasier, 1972;Manchee and Hasegawa, 1973) and that the explosion depth estimates seem fairly accurate with this method because of the good agreement between different authors using differing stations for common events. However, these authors knew a priori that the events were explosions, and they are not able to suggest that the events can be classified as explosions on the basis of shallow-focus estimates.…”

Section: 'Imentioning

confidence: 99%

“…Am., 63, 59-100. Cohen, T. (1970). Source-depth determinations using spectral, pseudo-autocorrelation, and cepstral analysis.…”

Section: 'Imentioning

confidence: 99%

Seismic Discrimination of Earthquakes and Explosions, with Application to the Southwestern United States

Seggern¹,

Rivers²

1979

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This study examines seismic discrimination between underground nuclear explosions and earthquakes in the Southwestern United States. A thorough review of theoretical and applied research on this problem, especially as it relates to that region, is presented first, followed by a presentation of the seismic discrimination parameters computed for a suite of events in the Southwest and a series of experiments with multi-dimensional discrimination.Review of past work finds some theoretical support for successful discrimination based upon several distinct measurements on seismic recordings.Although negative first motion and presence of pP both indicate a natural earthquake source, they cannot be found confidently in many cases. The rela-* deeper earthquakes could be identified by higher modes and a relative decrease of shorter period amplitude. The region under study extends from California to the southern Rocky Mountains and from roughly 40*N to the Gulf of California. A region of high seismicity, it is also a complex region encompassing several tectonic provinces, including the Basin-Range Province where the Nevada Test Site is located. Source mechanisms are diverse over the entire region and even within small subregions. Focal depths are almost all < 15 km and few depths can be determined reliably from teleseismic recordings. Twelve earthquakes, -3-mostly selected because of low M estimates from other studies, and eleven s explosions comprised the sources for this study. Seven teleseismic LRSM stations supplied the seismic data.In general, seismic discriminant parameters obtained from the recordings reflected the theoretical expectations of earthquake-explosion differences.Path-station effects were large for every parameter, especially for shortperiod data. Love-wave magnitudes were a superior discriminant when plotted versus mb. Shear waves, if measurable, were also excellent. The common Mmb plot shows three earthquakes with anomalously low Ms: the Denver earthquake, a Benham aftershock, and a Baja California earthquake.All the discrimination parameters (10) were applied in various combinations through a stepwise linear discriminant program, which treated the twentythree events as a training set. Using all parameters, the lowest a posteriori probability of correct classification was .987. Multi-dimensional discrimination using network averages for parameters was superior to using single-station parameters or using linear combinations of individual stations' discriminant functions.

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“…The procedure followed is a modified version of Cohen's (1970) method, and assumes similarity of pulse shape between the P phase and the corresponding surface reflected phase which follows after a time t given by 2d cos e ta (1)…”

Section: Depth Of Focusmentioning

confidence: 99%

Broach Earthquake of March 23, 1970

Arora

Nair

Varghese

1971

Seismological Research Letters

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A straightforward method has been developed to simulate the geometrie ray paths and travel times of seismic waves propagating through a medium with any specified velocity distribution. Using two-or three-dimensional models, one can test hypotheses of complicated and detailed velocity distributions within the earth by comparing travel times using digital models with travel times from actual earthquakes and explosions.

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Source-Depth Determinations using Spectral, Pseudo-Autocorrelation and Cepstral Analysis

Cited by 56 publications

References 1 publication

Modeling near‐field and teleseismic observations from the Amchitka Test Site

Modeling near‐field and teleseismic observations from the Amchitka Test Site

Seismic Discrimination of Earthquakes and Explosions, with Application to the Southwestern United States

Broach Earthquake of March 23, 1970

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