FORECASTING OF EARTHQUAKES

Press, Volume LXXIII, Issue 22003, 29 January 1937, Page 10

FORECASTING OF EARTHQUAKES

♦ NECESSARY WORK IN

NEW ZEALAND

SYDNEY SCIENTIST'S ADVICE

APPARATUS AND STAFF REQUIRED

[THE PRESS Special Service.]

WESTPORT, January 28

That the time and place of major earthquake disturbances in New Zealand could be definitely foretold if the Government would spend the money necessary to provide the required apparatus and to maintain the service is the considered opinion of Major Edgar Booth, M.C., D.Sc, F.lnst.P. (England), lecturer in physics and applied physics at the University of Sydney. Major Booth, who is touring New Zealand after attending the science congress at Auckland, made this statement to a representative of "The Press" at Westport to-day. "I wish to make it clear that I do not by any means claim that earthquakes can be foretold with unfailing accuracy," said Major Booth. "The degree of accuracy would be about equivalent to the accuracy of the best meteorological forecasts. "All that is required," he said, "is a number of relatively cheap seismographs placed at various points throughout the country, particularly in the neighbourhood of the principal known fault lines. These would have to be equipped with continuous film recorders giving a permanent record of all earth movements, and a suitably trained staff would have to be maintained to marshal the data from the various instruments to enable it to be properly interpreted." How It is Done How the forecasting is done was explained by Major Booth, and the underlying principle is simple enough. Earth tremors or microseisms originating from a certain fault line would affect separate recording instruments which would also mutually show the direction in which the earth waves were travelling. By following these direction lines from three or more instruments back to the point where they intersected the source of the movements could be accurately located. Continuous observations of the seismic waves propagated by earth movements at this zone' would thenceforwards be made. If they continued regularly all would probably be well because that would indicate a continuous and gradual adjustment of the stresses at that point. If, however, there was a cessation of the tremors combined with a gradual earth tilt in that neighbourhood then that would probably indicate the gradual building up of stresses or forces with the probability cf an eventual violent adjustment in the form of a more or less destructive earthquake. In order to keep -watch on this tilting of the land —imperceptible, of course, except to delicate instruments —which required to be correlated with the record of the earth tremors made by the seismographs, it would be necessary to employ tilt meters. Major Booth likened the process to a state of war in which the earth at the fault line "represented the enemy and the earth tremors the enemy artillery. So long as the firing continued regularly and without interruption then you knew what the enemy was doing, but if he suddenly became silent for a period you wanted to know what he was doing and whether he was preparing for a big attack.

Accuracy of Forecasts

Regarding the accuracy of seismic forecasts, Major Booth said it was not possible to foretell the actual date of an earthquake years ahead, but it was often possible to state fairly definitely that an earthquake would occur in a certain year. As the time of the major movement approached—as indicated by increasing earth tilt —then a more accurate forecast as to time could be made because violent movements were almost invariably preceded by a series of tell-tale minor shocks as the rock strata- first began to fracture. When this occurred after a long period of quiet and after tilting of the surface had been continuing then the near approach of a major adjustment was almost certain. At this stage it should be possible to state with assurance that a big earthquake would probably occur in, say, a week's time, and steps could then be taken to move the population and any portable, valuable property to a place of safety. "The cost of the necessary instruments for New Zealand," said Major Booth, "would probably be from £SOOO to £6OOO, and it would probably require about £7OOO a year to carry on the work, but that is surely a trifling sum compared with the saving of life and property that would probably result. The saving in property alone would be worth the expenditure, and as for human life—well, it is impossible to place a value on it." A great deal of work along these lines in the study and prognostication of seismic phenomena had been carried out in Japan in recent years, and already it had resulted in saving the inhabitants of many communities threatened with disaster. In order to provide the staff necessary to carry on this important work in New Zealand Major Booth advocated the establishment of a chair of applied geophysics at one of the New Zealand University Colleges, and he said that this would facilitate the training of experts, not only in seismology, but also in the various other branches of applied geophysics including meteorology, electrophysics, atmosphysics and geophysical surveying which was of great value in mining and certain departments of civil engineering.-

Interest of Insurance Companies

The insurance companies in Australia had taken great interest in this modern development of earthquake prediction in view of the earthquake risks they were asked to cover, and had contributed financially towards the cost of research. There was every reason for similar interest being taken by the insurance companies in New Zealand in the establishment of research here.

"You have had bad earthquakes in New Zealand in the past and you are certain to have more in the future," said Major Booth, "and for that reason you should be studying more extensively these phenomena in thkcountry. The method of earthquake prophecy I have described is not infallible and there will, no doubt, be many mistakes. Our researches so far have hardly touched the fringe of the subject, but the more work that is done on it the more we will find out about the prediction of earthquake?." There was available in New Zealand, in Dr. Mavsden, a man very capable to take charge of the work, he said. Major Booth said he had put his suggestions forward at the Science Congress at Auckland, but had been told

that the New Zealand Government would probably not be prepared to spend the money required. That would surely ba a wrong attitude to take up. because if the institution of a proper system of recording and interpreting earth movements resulted in saving as few as a dozen lives, it would be well worth while. In his trip down the Buller from Nelson to Wcstport. Major Booth was able to observe and photograph some of the effects of the 1929 earthquake. He and Mrs Booth and their daughter are deeply impressed with New Zealand's seenic attractions, particularly the native bush.