| Autor: |
DOUGLAS, A., LILWALL, R. C. |
| Zdroj: |
Nature; November 1968, Vol. 220 Issue: 5166 p469-470, 2p |
| Abstrakt: |
AT 21.00.00.1 GMT on October 29, 1965, a nuclear explosion was detonated underground on Amchitka Island (Aleutian Islands). Study of the seismic waves generated by this explosion—code named Longshot—showed that the arrival times of P waves at stations on azimuths to the north of the Aleutian arc are earlier than predicted whereas the arrival times to the south of the arc are usually later than predicted. Epicentres computed by standard methods from the arrival times are consistently about 25 km to the north of the true epicentre. This phenomenon, now described as travel time bias, was not recognized before the firing of Longshot: the predicted P travel times of large explosions elsewhere are close to those observed and the calculated epicentres are within a few kilometres of the known locations. Some workers1,2have interpreted this travel time bias as originating near the source of the explosion (source bias) and Cleary2has deduced a possible near source structure to account for it. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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