Newly Discovered Underground Wave

Discovery of a new type of underground earthquake wave, vitally affecting seismological theories and problems of building reinforcement, was reported today by Dr. L. Don Leet, Director of the University Seismograph Stations.

Disclosed by a series of observations of artificial earthquakes set off by dynamite explosions, the new wave-form is the fifth fundamental type known to science. The four previously known forms have been recognized for forty years. Dr. Leet said his new wave was not predicted in earthquake theory.

Because of its importance in tremors arising from explosions, the new wave is expected to play a considerable part in proposed uses of the seismograph in army artillery observation, for the location of heavy enemy guns, and also for computation by a gun crew of their accuracy of fire. Both the discharge of a cannon and the explosion of a shell set up vibrations underground which can be traced by earthquake instruments.

While the new wave form has been observed only in records of explosions and has not yet been detected on records of natural earthquakes, Dr. Leet believes that "almost certainly" it will eventually be found among the natural tremors. He pointed out that in all other respects the natural and artificial earthquakes have proved to be similar.

A question which needs immediate investigation, Dr. Leet said, is whether the new wave form is mingled with the waves close to the sources of earthquakes, which do greatest damage. It may be found important to modify designs of earthquake-proof structures, to meet ground conditions set up by the wave.