CAN EARTHQUAKES BE PREDICTED?

Dominion, Volume 32, Issue 232, 29 June 1939, Page 13

CAN EARTHQUAKES BE PREDICTED?

Not With Accuracy, Says

Scientist

STUDY OF CRUST STRAIN ADVOCATED

There were two distinct points of view from which the topic of earthquakes might be considered—either as a menace to be dealt with, or as a tool to be used in investigating the inner structure of the earth, said Dr. Lyndon Bastings In a lecture on earthquakes to members of the Royal Society of New Zealand in the lecture hall of the Dominion Museum last night. Before the development of modern seismology, gravitational and magnetic evidence bad indicated that the deep interior of the earth probably contained a large mass of metallic iron. The study of records of large earthquakes had not only confirmed this idea, but had made it possible to define the boundary of this Iron core with some precision. It appeared to be symmetrically situated at the centre of the earth, and to have a radius of about 2000 miles, or a little more than onehalf of the earthls radius. Its boundary was fairly sharply marked off from the manti* outside, and in consequence earthquake waves were reflected sharply when they met it. On returning to the surface again, they recorded their story of the encounter in terms which were capable of interpretation. Prediction of Earthquakes.

A complete and accurate prediction of an earthquake had never been made, and probablv never would be, said Dr. Bastings, ‘For a description of an earthquake, either past or future, to be accurate, it had to specify the locality, the time and the magnitude of the initial distui'bifrice. So many incidental factors were capable of influencing both the time and the magnitude of the shock, that there was very little hope of sufficient knowledge ever being assembled to deal adequately with al! of them. It would be much more profitable if an intensive study was made of the.signs of growing strain In the rocky crust, in order to be able to foresee which . localities were most liable to a visitation in the future, and so to be able to lay the foundations of a sound policy in regard to building safety commensurate with the indicated risks. The lecture was illustrated by a number of slides and diagrams, many of which \ were reproductions of seismograms of various New Zealand earthquakes as recorded in distant parts of the world.