Abstract
Mr. J. M. Stagg, of the Kew Observatory, Richmond, Surrey, writes that the effects of the explosion of a cargo of nitrate in Brest harbour on the evening of July 28 were clearly recorded on one of the seismographs and on four barographs at the Observatory, which is 480 km. from Brest. The seismograph, a short-period, vertical component instrument, recorded the first effect at 16h. 48m. 52s. G.M.T. with a second pulse nine seconds later. The biggest amplitude occurred at 16h. 49m. 05s. and the whole disturbance lasted about one minute. The character of the effect on the seismograph closely resembled the effects produced by bomb explosions, flying bombs, etc., in the neighbourhood of the Observatory during the War, when, for the most part, the disturbances were due to airborne sound waves. That the seismograph disturbance was due to the explosion air wave and not to true earth movements is supported by the times of the disturbance recorded by the Kew barographs, including a very sensitive microbarograph. All four instruments showed a sudden pulse (about one millibar) of very short duration in both directions, the mean of the times being 16h. 49m. Os. ± 15s. The Kew records taken together put the time of the Brest explosion at about 16h. 25m. G.M.T.: there was no indication of an earth movement or an upper air sound wave.
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Recordings at Kew of the Brest Explosion. Nature 160, 184 (1947). https://doi.org/10.1038/160184b0
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DOI: https://doi.org/10.1038/160184b0