Rensselaer Journal, Volume 10, Number 47, Rensselaer, Jasper County, 2 May 1901 — SPEED OF AN EARTHQUAKE. [ARTICLE]

SPEED OF AN EARTHQUAKE.

Preliminary Tremors Travel at the Rato of 345 Miles a Minute. Speaking of the Indian earthquakes of 1897, a London scientist says the 1 , vibrations traveled to Europe, where they were recorded at very many sta-' tions, and no donbt would have been equally well recorded at any other places on the surface of our world had there been provided suitable instruments. The preliminary tremors, which are probably waves of compression, traveled through the world to reach Italy and other countries with an average rate of 345 miles per minute, or 9.0 kilometers per second—a rate which, it will be observed, is higher than that at which similar movements can be transmitted through glass or steeL The large waves, which are probably quasl-elas-tic gravitation waves, by .traveling over the surface of the earth, reached Europe at a rate of 113 miles per minute, or 2.98 kilometers per seconds. It Is likely that these latter disturb-; ances reached stations in Europe by; traveling from their origin in two di-: rectlons round the world. As an indication of this, we are told that at sev-i eral of the European stations slight undulations are to be seen on the* seismograms at times we should ex-| pect to find such markings, had they, traveled from India to Europe by the' longest possible route. From the period of these waves, which is taken at twenty-two seconds, and their velocity, their length may be inferred, an estimate of which is thirty-four miles; while their height, as deducted from their length, and the maximum angle of tilting, Is estimated at twenty Inches. The slowness of the movement was such that they could not be felt, while the magnitude was such that the unaided eye of an observer would not be able to recognize any differential movements In his surroundings. The largeness of these disturbances and their great duration, extending over several hours, preclude them from the category of tremors, vibrations or microsclsms.— Dispatch.