The Propagation of Earthquake Vibrations through the Earth

Abstract

The history of seismological research and discovery may be conveniently divided into three great epochs. 1. We have the recording of earthquakes in the popular significance of the term, with an enquiry into their character, based almost entirely upon the (usually) destructive results of their visitation. 2. We find investigators beginning to appeal to experiment to elucidate some of the effects noticed, with a growing appreciation of the necessity of recording all palpable earthquakes, whether destructive or not. One of the most honoured names in this connection is that of Mallet, whose two volumes on “The Great Neapolitan Earthquake” form a classic in the literature of the subject. Most of the developments of recent times will be found in embryo in the pages of this monumental work. 3. The introduction of instruments for recording earthquakes, and, as a natural consequence, the recognition of pulsations and tremors and the various kinds of earthquake too feeble to be detected by our senses.

At every stage in this history, geological and physical problems of intrinsic difficulty have been encountered; and it is to the discussion of some of the most recent of these that this address is devoted.

From the days of Mallet and Hopkins, numerous reports on earthquakes and seismological phenomena have been prepared and published by the British Association; and the last of these, from the industrious pen of J. Milne, F.R.S., formerly Professor of Mining in the Imperial University of Japan, has a surpassing wealth of detailed facts and of suggested theories.