Artificial Seismic Waves Research Articles

SEISMIC EFFICIENCY OF EXPLOSIVES*

ABSTRACTThe parameters which characterize an explosive are derived from laboratory tests and none is directly usable for seismic purposes. Another one, derived from field experiments is proposed in this paper. It allows the comparison of two different explosives. The test must be conducted with care. Precautions concerning the equipment and the shot point detailed. The first available results suggest that the new parameter does not depend on the size of the charge nor on the shooting conditions, though the experimental data are not numerous enough to allow a general statement. It is shown how a coefficient of seismic efficiency can be used for selecting an explosive; and considerable amounts of money can be saved by the best choice. More studies on the generation of artificial seismic waves would be highly profitable.

THE STATE OF SEISMIC PROSPECTING

The application of physics to the search for minerals and especially for petroleum began in earnest after the first World War. As Weatherby has stated in his excellent paper on The History and Development of Seismic Prospecting (1940) “the stage had been carefully set and the players were ready to perform their new roles as prospectors.” Minthrop in Germany and Karcher, Hasemann, Eckhardt, and McCullom in this country were considering the use of artificial seismic waves in finding oil‐bearing structure. Ferdinand Suess in Hungary was building Eötvös torsion balances and the Askania Company in Germany was constructing torsion balances and magnetometers.

Bibliography of Seismology

THE Bibliography of Seismology for the period July-December 1941, prepared at the Dominion Observatory, Ottawa, by Mr. Ernest A. Hodgson (now president of the Seismological Society of America), has just been received. It covers 145 items, ranging through pure and applied seismology, building construction, cosmogony, engineering, instruments, insurance, oceanography and time-keeping. About forty-five items deal with seismic prospecting and patents associated with it, and forty-two items deal with instruments, chiefly for the detection of various types of natural and artificial seismic waves. Items in NATURE are listed. Several items deal with seismic surveying in the U.S.S.R. (for example, “Prospects of Seismic Survey by the Method of Refracted Waves in the Region of Ust-Eniseisk Port” by R. M. Demenitskaia, Problemi Arktiki, No. 5, 81-92, Leningrad, 1939), and it is not known whether or not the War has interfered with many of these projects. From time to time luminous phenomena have been reported as accompanying seismic phenomena, and one such is listed: “Sur les phénomènes lumineux qui ont accompagné le tremblement de terre de Roumanie du 10 novembre 1940”, G, Demetrescu and G. Petrescu, Académie Roumaine, Bulletin de la Section Scientifique, Tome 23, No. 6, pp. 5, 1 chart, Jan., 1941."