Travel times and amplitudes from the Salmon explosion

Jordan, James N.; Mickey, W.V.; Helterbran, Wayne; Clark, Don M

doi:10.1029/jz071i014p03469

Cited by 24 publications

(3 citation statements)

References 6 publications

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“…The data were obtained for nuclear explosions mainly from reports on long-range seismic measurements (LRSM) (LRSM Shoal, 1963;LRSM Salmon, 1964;LRSM Gasbuggy, 1967;LRSM Rio Blanco, 1974) and partially from literature (LEHMAN, 1964;ROMNEY et al, 1962;JORDAN et al, 1966;SPRINGER and KINNAMAN, 1971;RF/US CALIBRATION WORKING GROUP, 1998). All of these events were very shallow, and thus zero depth was used for all of them.…”

Section: Seismic Travel-time Data Collection and Analysismentioning

confidence: 99%

Application of 3-D Crustal and Upper Mantle Velocity Model of North America for Location of Regional Seismic Events

Ryaboy¹,

Baumgardt

Firbas³

et al. 2001

Pure appl. geophys.

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Ð Seismic event locations based on regional 1-D velocity-depth sections can have bias errors caused by travel-time variations within dierent tectonic provinces and due to ray-paths crossing boundaries between tectonic provinces with dierent crustal and upper mantle velocity structures. Seismic event locations based on 3-D velocity models have the potential to overcome these limitations. This paper summarizes preliminary results for calibration of IMS for North America using 3-D velocity model. A 3-D modeling software was used to compute Source-Station Speci®c Corrections (SSSCs(3-D)) for Pn travel times utilizing 3-D crustal and upper mantle velocity model for the region. This research was performed within the framework of the United States/Russian Federation Joint Program of Seismic Calibration of the International Monitoring System (IMS) in Northern Eurasia and North America.An initial 3-D velocity model for North America was derived by combining and interpolating 1-D velocity-depth sections for dierent tectonic units. In areas where no information on 1-D velocity-depth sections was available, tectonic regionalization was used to extrapolate or interpolate. A Moho depth map was integrated. This approach combines the information obtained from refraction pro®les with information derived from local and regional network data. The initial 3-D velocity model was tested against maps of Pn travel-time residuals for eight calibration explosions; corrections to the 3-D model were made to ®t the observed residuals. Our goal was to ®nd a 3-D crustal and upper mantle velocity model capable predicting Pn travel times with an accuracy of 1.0±1.5 seconds (r.m.s.).The 3-D velocity model for North America that gave the best ®t to the observed travel times, was used to produce maps of SSSCs(3-D) for seismic stations. The computed SSSCs(3-D) vary approximately from +5 seconds to )5 seconds for the western USA and the Pre-Cambrian platform, respectively. These SSSCs(3-D) along with estimated modeling and measurement errors were used to relocate, using regional data, an independent set of large chemical explosions (with known locations and origin times) detonated within various tectonic provinces of North America. Utilization of the 3-D velocity model through application of the computed SSSCs(3-D) resulted in a substantial improvement in seismic event location accuracy and in a signi®cant decrease of error ellipse area for all events analyzed in comparison both with locations based on the IASPEI91 travel times and locations based on 1-D regional velocity models.

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Section: Seismic Travel-time Data Collection and Analysismentioning

confidence: 99%

Application of 3-D Crustal and Upper Mantle Velocity Model of North America for Location of Regional Seismic Events

Ryaboy¹,

Baumgardt

Firbas³

et al. 2001

Pure appl. geophys.

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“…-67-1.16x105 (Jordan et, al, 1966) 10 4 - 1t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Figure 20. Amplitude-distance relations for the P and P (phase velocity mx greater than 5 km/sec) phase from SALMON.…”

Section: Distance Admplitudementioning

confidence: 99%

Regional Amplitude-Distance Relations, Discrimination and Detection

Blandford¹,

Hartenberger²,

Naylor³

1981

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Amplitude-distance curves are different in the EUS and WUS; P decays-2.5-3.0 max as r and r in EUS and WUS, while for the maximum after 3.6 km/sec on-2-3 the vertical component (termed Lg) the decay rates are r and r. The EUS results are in general agreement with the literature and with the data presented by Nersesov and Rautian (1964) for events on the northern margin of tectonic regions in the Soviet Union suggesting that discrimination results in the EUS are relevant to NSS stations within the Soviet Union. Using these distance amplitude relations, network mean amplitudes at 1000 km were computed for L and P for earthquakes and explosions in the g max EUS and WUS and a separation of 0.6 magnitude units was observed thus forming a regional discriminant. The L is larger for earthquakes than for explosions. g This conclusion is somewhat uncertain in the WUS because of the large scatter in the explosion population. However, a reasonable explanation for this large scatter is that the small events at NTS are at such shallow depths in dry alluvium that the medium is weak, resulting in a low corner frequency. This decreases the ratio P /L since P contains comparatively more high frequency than L. The scatter probably would not be a problem in a true test ban situg ation since shots will be well buried to avoid surface collapse.

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“…The locations of these four stations are indicated by squares on Figure 17 which provides a map view of the North American Stations which recorded the SALMON event (Jordan, et al, 1966).…”

Section: Accomplishmentsmentioning

confidence: 99%