In accepting a commission to present a paper on a prescribed subject, a speaker tacitly reserves the right to make his own interpretation of the title assigned. Let us examine the limitations which one might define when considering, from the viewpoint of seismology, the symposium subject: “The Interior of the Earth Viewed in Its Relation to Earthquake Causes”.
The first limitation which seems justified is that the discussion should be confined to that part of the earth’s interior where conditions or potentials exist which do or which may contribute to the cause of earthquakes. As most earthquakes originate at depths ranging from, say, a kilometer to about 700 km., one might at first thought decide to consider only the spherical shell within the earth which is bounded by these two horizons.
That there is ample scope for discussion even with this stricture may be taken for granted. It would be . . .