Mathematical questions in seismology

Seismologists, like mathematicians, are accustomed to dividing their subject into a pure and an applied branch. The desirability of such division is underlined by the manner in which non-seismologists frequently approach the subject. It is too often taken for granted that, because an earthquake is a motion of the ground, seismology must be chiefly concerned with the detailed analysis of that motion for its own sake. Such analysis is important in the engineering section of applied seismology; but it is unrepresentative of seismology as a whole, which deals largely with more remote problems: the causative mechanism of earthquakes, the distribution of their origins geographically and in depth, or the structure and physical condition of the interior of the earth.